TY - JOUR AB - Date palm (Phoenix dactylifera L.) is an important crop in arid regions that is well-adapted to desert ecosystems. To understand the remarkable ability to grow and yield in water-limited environments, experiments with water-withholding for up to four weeks were conducted. In response to drought, root, rather than leaf, osmotic strength increased, with organic solutes such as sugars and amino acids contributing more to the osmolyte increase than minerals. Consistently, carbon and amino acid metabolism was acclimated toward biosynthesis at both the transcriptional and translational levels. In leaves, a remodeling of membrane systems was observed, suggesting changes in thylakoid lipid composition, which together with the restructuring of the photosynthetic apparatus, indicated an acclimation preventing oxidative damage. Thus, xerophilic date palm avoids oxidative damage under drought by combined prevention and rapid detoxification of oxygen radicals. Although minerals were expected to serve as cheap key osmotics, date palm also relies on organic osmolytes for osmotic adjustment of the roots during early drought acclimation. The diversion of these resources away from growth is consistent with date palm's strategy of generally slow growth in harsh environments and clearly indicates a trade-off between growth and stress-related physiological responses. AU - Franzisky, B.L.* AU - Mueller, H.M.* AU - Du, B.* AU - Lux, T. AU - White, P.J.* AU - Carpentier, S.C.* AU - Winkler, J.B. AU - Schnitzler, J.-P. AU - Kudla, J.* AU - Kangasjärvi, J.* AU - Reichelt, M.* AU - Mithöfer, A.* AU - Mayer, K.F.X. AU - Rennenberg, H.* AU - Ache, P.* AU - Hedrich, R.* AU - Messerer, M. AU - Geilfus, C.M.* C1 - 72310 C2 - 56581 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 1244-1265 TI - Date palm diverts organic solutes for root osmotic adjustment and protects leaves from oxidative damage in early drought acclimation. JO - J. Exp. Bot. VL - 76 IS - 4 PB - Oxford Univ Press PY - 2024 SN - 0022-0957 ER - TY - JOUR AB - Defense responses in plants are based on complex biochemical processes. Systemic acquired resistance (SAR) helps to fight infections by (hemi-)biotrophic pathogens. One important signaling molecule in SAR is pipecolic acid (Pip), accumulation of which is dependent on the aminotransferase ALD1 in Arabidopsis. While exogenous Pip primes defense responses in the monocotyledonous cereal crop barley (Hordeum vulgare), it is currently unclear if endogenous Pip plays a role in disease resistance in monocots. Here, we generated barley ald1 mutants using CRISPR/Cas9, and assessed their capacity to mount SAR. Endogenous Pip levels were reduced after infection of the ald1 mutant, and this altered systemic defense against the fungus Blumeria graminis f. sp. hordei. Furthermore, Hvald1 plants did not emit nonanal, one of the key volatile compounds that are normally emitted by barley plants after the activation of SAR. This resulted in the inability of neighboring plants to perceive and/or respond to airborne cues and prepare for an upcoming infection, although HvALD1 was not required in the receiver plants to mediate the response. Our results highlight the crucial role of endogenous HvALD1 and Pip for SAR, and associate Pip, in particular together with nonanal, with plant-to-plant defense propagation in the monocot crop barley. AU - Brambilla, A. AU - Lenk, M. AU - Ghirardo, A. AU - Eccleston, L. AU - Knappe, C. AU - Weber, B. AU - Lange, B. AU - Imani, J.* AU - Schäffner, A. AU - Schnitzler, J.-P. AU - Vlot, A.C. C1 - 67736 C2 - 54044 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 3033-3046 TI - Pipecolic acid synthesis is required for systemic acquired resistance and plant-to-plant-induced immunity in barley. JO - J. Exp. Bot. VL - 74 IS - 10 PB - Oxford Univ Press PY - 2023 SN - 0022-0957 ER - TY - JOUR AB - Plants often face simultaneous abiotic and biotic stress conditions; however, physiological and transcriptional responses under such combined stress conditions are still not fully understood. Spring barley (Hordeum vulgare) is susceptible to Fusarium head blight (FHB), which is strongly affected by weather conditions. We therefore studied the potential influence of drought on FHB severity and plant responses in three varieties of different susceptibility. We found strongly reduced FHB severity in susceptible varieties under drought. The number of differentially expressed genes (DEGs) and strength of transcriptomic regulation reflected the concentrations of physiological stress markers such as abscisic acid or fungal DNA contents. Infection-related gene expression was associated with susceptibility rather than resistance. Weighted gene co-expression network analysis revealed 18 modules of co-expressed genes that reflected the pathogen- or drought-response in the three varieties. A generally infection-related module contained co-expressed genes for defence, programmed cell death, and mycotoxin detoxification, indicating that the diverse genotypes used a similar defence strategy towards FHB, albeit with different degrees of success. Further, DEGs showed co-expression in drought- or genotype-associated modules that correlated with measured phytohormones or the osmolyte proline. The combination of drought stress with infection led to the highest numbers of DEGs and resulted in a modular composition of the single-stress responses rather than a specific transcriptional output. AU - Hoheneder, F.* AU - Steidele, C.E.* AU - Messerer, M. AU - Mayer, K.F.X. AU - Köhler, N.* AU - Wurmser, C.* AU - Heß, M.* AU - Gigl, M.* AU - Dawid, C.* AU - Stam, R.* AU - Hückelhoven, R.* C1 - 68615 C2 - 54745 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 6820-6835 TI - Barley shows reduced Fusarium head blight under drought and modular expression of differentially expressed genes under combined stress. JO - J. Exp. Bot. VL - 74 IS - 21 PB - Oxford Univ Press PY - 2023 SN - 0022-0957 ER - TY - JOUR AB - Plants activate biochemical responses to combat stress. (Hemi-)biotrophic pathogens are fended off by systemic acquired resistance (SAR), a primed state allowing plants to respond faster and stronger upon subsequent infection. Here, we show that SAR-like defences in barley (Hordeum vulgare) are propagated between neighboring plants, which respond with enhanced resistance to the volatile cues from infected senders. The emissions of the sender plants contained 15 volatile organic compounds (VOCs) associated with infection. Two of these, β-ionone and nonanal, elicited resistance upon plant exposure. Whole genome transcriptomics analysis confirmed that inter-plant propagation of defence in barley is established as a form of priming. Although gene expression changes were more pronounced after challenge infection of the receiver plants with Blumeria graminis f. sp. hordei, differential gene expression in response to the volatile cues of the sender plants included an induction of HISTONE DEACETYLASE 2 (HvHDA2) and priming of TETRATRICOPEPTIDE REPEAT-LIKE superfamily protein (HvTPL). Because HvHDA2 and HvTPL transcript accumulation was also enhanced by exposure of barley to β-ionone and nonanal, our data identify both genes as possible defence/priming markers in barley. Our results further suggest that VOCs and plant-plant interactions are relevant for possible crop protection strategies priming defence responses in barley. AU - Brambilla, A. AU - Sommer, A. AU - Ghirardo, A. AU - Wenig, M. AU - Knappe, C. AU - Weber, B. AU - Amesmaier, M. AU - Lenk, M. AU - Schnitzler, J.-P. AU - Vlot, A.C. C1 - 63733 C2 - 51649 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 615–630 TI - Immunity-associated volatile emissions of β-ionone and nonanal propagate defence responses in neighbouring barley (Hordeum vulgare) plants. JO - J. Exp. Bot. VL - 73 IS - 2 PB - Oxford Univ Press PY - 2022 SN - 0022-0957 ER - TY - JOUR AB - Crop multi-model ensembles (MME) have proven to be effective in increasing the accuracy of simulations in modelling experiments. However, the ability of a MME to capture crop response to changes in sowing dates and densities has not yet been investigated. These management interventions are some of the main levers for adapting cropping systems to climate change. Here, we explore the performance of a MME of 29 wheat crop models to predict the effect of changing sowing dates and rates on yield and yield components, on two sites located in a high-yielding environment in New Zealand. The experiment was conducted for 6 years and provided 50 combinations of sowing date, sowing density and growing season.". We show that the MME simulates seasonal growth of wheat well under standard sowing conditions, but fails under early sowing and high sowing rates. The comparison between observed and simulated in-season fraction of intercepted photosynthetically active radiation (FIPAR) for early sown wheat shows that the MME does not capture the decrease of crop above ground biomass during winter months due to senescence. Models need to better account for tiller competition for light, nutrients and water during vegetative growth, and early tiller senescence and tiller mortality, which are exacerbated by early sowing, high sowing densities and warmer winter temperatures. AU - Dueri, S.* AU - Brown, H.* AU - Asseng, S.* AU - Ewert, F.* AU - Webber, H.* AU - George, M.* AU - Craigie, R.* AU - Guarin, J.R.* AU - Pequeno, D.N.L.* AU - Stella, T.* AU - Ahmed, M.* AU - Alderman, P.D.* AU - Basso, B.* AU - Berger, A.G.* AU - Mujica, G.B.* AU - Cammarano, D.* AU - Chen, Y.* AU - Dumont, B.* AU - Rezaei, E.E.* AU - Fereres, E.* AU - Ferrise, R.* AU - Gaiser, T.* AU - Gao, Y.* AU - Garcia-Vila, M.* AU - Gayler, S.* AU - Hochman, Z.* AU - Hoogenboom, G.* AU - Kersebaum, K.C.* AU - Nendel, C.* AU - Olesen, J.E.* AU - Padovan, G.* AU - Palosuo, T.* AU - Priesack, E. AU - Pullens, J.W.M.* AU - Rodriguez, A.* AU - Rötter, R.P.* AU - Ramos, M.R.* AU - Semenov, M.A.* AU - Senapati, N.* AU - Siebert, S.* AU - Srivastava, A.K.* AU - Stöckle, C.* AU - Supit, I.* AU - Tao, F.* AU - Thorburn, P.* AU - Wang, E.* AU - Weber, T.K.D.* AU - Xiao, L.* AU - Zhao, C.* AU - Zhao, J.* AU - Zhao, Z.* AU - Zhu, Y.* AU - Martre, P.* C1 - 65545 C2 - 52733 SP - 5715-5729 TI - Simulation of winter wheat response to variable sowing dates and densities in a high-yielding environment. JO - J. Exp. Bot. VL - 73 IS - 16 PY - 2022 SN - 0022-0957 ER - TY - JOUR AB - Male sterile lines play important roles in plant breeding to obtain hybrid vigour. The male sterility Lembke (MSL) system is a thermosensitive genic male sterility system of Brassica napus and is one of the main systems used in European rapeseed breeding. Interestingly the MSL system shows high similarity to the 9012AB breeding system from China including the ability to revert to fertile in high temperature conditions. Here we demonstrate that the MSL system is regulated by the same restorer of fertility gene BnaC9-Tic40 as the 9012AB system, which is related to the translocon at the inner envelope membrane of chloroplasts 40 (TIC40) from Arabidopsis. The male sterility gene of the MSL system was also identified to be a chloroplast localised protein which we call BnChimera, this gene shows high sequence similarity to the sterility gene previously described for the 9012AB system. For the first time a direct protein interaction between the BnaC9-Tic40 and the BnChimera could be demonstrated. In addition, the corresponding amino acids that mediate this interaction were identified and possibly determine how BnaC9-Tic40 acts as the restorer of fertility. Using an RNA-seq approach, the effects of heat treatment on the male fertility restoration of an MSL system line C545 were investigated. This data demonstrated that many pollen developmental pathways were affected by the higher temperatures. It is hypothesised that heat stress reverses the male sterility via a combination of slower production of cell wall precursors in plastids and a slower flower development, which ultimately results in fertile pollen. The potential breeding applications of these results are discussed regarding the capacity of using the MSL system in producing thermotolerant fertile plants. AU - Schuhmann, P.* AU - Engstler, C.* AU - Klöpfer, K.* AU - Gügel, I.L.* AU - Abbadi, A.* AU - Dreyer, F.S.* AU - Leckband, G.* AU - Bölter, B.* AU - Hagn, F. AU - Soll, J.* AU - Carrie, C.* C1 - 64535 C2 - 52260 SP - 3531–3551 TI - Two wrongs make a right: Heat stress reversion of a male-sterile Brassica napus line. JO - J. Exp. Bot. VL - 73 IS - 11 PY - 2022 SN - 0022-0957 ER - TY - JOUR AB - Volatile organic compounds (VOCs) were originally identified as communication compounds between plants and insects. Today, we know that VOCs are released by organisms of all kingdoms, including bacteria and fungi, and mediate diverse intra- and interspecific interactions both above- and below-ground. Following recent trends in this research field, the majority of reviews and research papers in this special issue focus on possible biological and ecological functions and various other aspects of microbial VOCs (mVOCs). Additional reviews and research papers highlight connections between microbe-induced plant VOCs, and their possible application in future sustainable crop protection strategies. AU - Vlot, A.C. AU - Rosenkranz, M. C1 - 64068 C2 - 52054 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 445-448 TI - Volatile compounds-the language of all kingdoms? JO - J. Exp. Bot. VL - 73 IS - 2 PB - Oxford Univ Press PY - 2022 SN - 0022-0957 ER - TY - JOUR AB - The identification of those prevalent abscisic acid (ABA) receptors and molecular mechanisms that trigger drought adaptation in crops well adapted to harsh conditions such as date palm (Phoenix dactylifera, Pd) sheds light on plant-environment interactions. We reveal that PdPYL8-like receptors are predominantly expressed under abiotic stress, with Pd27 being the most expressed receptor in date palm. Therefore, subfamily I PdPYL8-like receptors have been selected for ABA signaling during abiotic stress response in this crop. Biochemical characterization of PdPYL8-like and PdPYL1-like receptors revealed receptor- and ABA-dependent inhibition of PP2Cs, which triggers activation of the pRD29B-LUC reporter in response to ABA. PdPYLs efficiently abolish PP2C-mediated repression of ABA signaling, but loss of the Trp lock in the seed-specific AHG1-like phosphatase PdPP2C79 markedly impairs its inhibition by ABA receptors. Characterization of Arabidopsis transgenic plants that express PdPYLs shows enhanced ABA signaling in seed, root, and guard cells. Specifically, Pd27-overexpressing plants showed lower ABA content and were more efficient than the wild type in lowering transpiration at negative soil water potential, leading to enhanced drought tolerance. Finally, PdPYL8-like receptors accumulate after ABA treatment, which suggests that ABA-induced stabilization of these receptors operates in date palm for efficient boosting of ABA signaling in response to abiotic stress. AU - Garcia-Maquilon, I.* AU - Coego, A.* AU - Lozano-Juste, J.* AU - Messerer, M. AU - de Ollas, C.* AU - Julian, J.* AU - Ruiz-Partida, R.* AU - Pizzio, G.* AU - Belda-Palazón, B.* AU - Gomez-Cadenas, A.* AU - Mayer, K.F.X. AU - Geiger, D.* AU - Alquraishi, S.A.* AU - Alrefaei, A.F.* AU - Ache, P.* AU - Hedrich, R.* AU - Rodriguez, P.L.* C1 - 61186 C2 - 49773 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 757-774 TI - PYL8 ABA receptors of Phoenix dactylifera play a crucial role in response to abiotic stress and are stabilized by ABA. JO - J. Exp. Bot. VL - 72 IS - 2 PB - Oxford Univ Press PY - 2021 SN - 0022-0957 ER - TY - JOUR AB - Nitric oxide (NO) is a redox-active gaseous signal uniformly present in eukaryotes, but its formation, signalling, and effects are specific within the plant kingdom in several aspects. NO synthesis in algae proceeds by mechanisms similar to that in mammals, but there are different pathways in higher plants. Beyond synthesis, the regulatory processes to maintain steady-state NO levels are also integral for the projection of NO function. As a key redox molecule, NO exhibits a number of pivotal molecular interactions, for example with reactive oxygen species, hydrogen sulfide, and calcium, with these molecular interplays largely underpinning NO bioactivity. In this context, NO has emerged as a key regulator in plant growth, development, and environmental interactions. In this special issue, a collection of reviews discusses the current state-of-the-art and possible future directions related to the biology and chemistry of plant NO function. AU - Kolbert, Z.* AU - Lindermayr, C. AU - Loake, G.J.* C1 - 61318 C2 - 50150 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 777-780 TI - The role of nitric oxide in plant biology: Current insights and future perspectives. JO - J. Exp. Bot. VL - 72 IS - 3 PB - Oxford Univ Press PY - 2021 SN - 0022-0957 ER - TY - JOUR AB - AGD2-like DEFENSE RESPONSE PROTEIN 1 (ALD1) is an aminotransferase that is necessary for the biosynthesis of the immune-active non-protein amino acid pipecolic acid (Pip). Pip and its N-hydroxylated derivative, N-hydroxy-Pip (NHP), have been suggested as possible long-distance signals moving in plants from infected to systemic, uninfected sites to enhance immunity. Jiang et al. (2021) show that accumulation of ALD1 in epidermal chloroplasts at local, infected sites promotes systemic immunity. Their results highlight the epidermis as a site of active immune signaling and ALD1 as an important upstream regulator of long-distance signal transmission in systemic acquired resistance (SAR). AU - Vlot, A.C. C1 - 61672 C2 - 50382 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 2266-2268 TI - A quest for long-distance signals: The epidermis as central regulator of pipecolic acid-associated systemic acquired resistance. JO - J. Exp. Bot. VL - 72 IS - 7 PB - Oxford Univ Press PY - 2021 SN - 0022-0957 ER - TY - JOUR AB - Nitric oxide (NO) is involved in a vast number of physiologically important processes in plants, such as organ development, stress resistance, and immunity. Transduction of NO bioactivity is generally achieved by post-translational modification of proteins, with S-nitrosation of cysteine residues as the predominant form. While traditionally the subcellular location of the factors involved was of lesser importance, recent studies identified the connection between NO and transcriptional activity and thereby raised the question about the route of NO into the nuclear sphere. Identification of NO-affected transcription factors and chromatin-modifying histone deacetylases implicated the important role of NO signaling in the plant nucleus as a regulator of epigenetic mechanisms and gene transcription. Here, we discuss the relationship between NO and its directly regulated protein targets in the nuclear environment, focusing on S-nitrosated chromatin modulators and transcription factors. AU - Wurm, C. AU - Lindermayr, C. C1 - 61237 C2 - 49716 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 808-818 TI - Nitric oxide signaling in the plant nucleus: The function of nitric oxide in chromatin modulation and transcription. JO - J. Exp. Bot. VL - 72 IS - 3 PB - Oxford Univ Press PY - 2021 SN - 0022-0957 ER - TY - JOUR AB - Isoleucic acid (ILA), a branched-chain amino acid-related 2-hydroxycarboxylic acid, occurs ubiquitously in plants. It enhances pathogen resistance and inhibits root growth of Arabidopsis. The salicylic acid (SA) glucosyltransferase UGT76B1 is able to conjugate ILA. Here, we investigate the role of ILA in planta in Arabidopsis and reveal a triad of distinct responses to this small molecule. ILA synergistically co-operates with SA to activate SA-responsive gene expression and resistance in a UGT76B1-dependent manner in agreement with the observed competitive ILA-dependent repression of SA glucosylation by UGT76B1. However, ILA also shows an SA-independent stress response. Nitroblue tetrazolium staining and pharmacological experiments indicate that ILA induces superoxide formation of the wild type and of an SA-deficient (NahG sid2) line. In contrast, the inhibitory effect of ILA on root growth is independent of both SA and superoxide induction. These effects of ILA are specific and distinct from its isomeric compound leucic acid and from the amino acid isoleucine. Leucic acid and isoleucine do not induce expression of defense marker genes or superoxide production, whereas both compounds inhibit root growth. All three responses to ILA are also observed in Brassica napus. AU - Bauer, S. AU - Mekonnen, D.W. AU - Geist, B. AU - Lange, B. AU - Ghirardo, A. AU - Zhang, W. AU - Schäffner, A. C1 - 59863 C2 - 49079 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 4258-4270 TI - The isoleucic acid triad: Distinct impacts on plant defense, root growth, and formation of reactive oxygen species. JO - J. Exp. Bot. VL - 71 IS - 14 PB - Oxford Univ Press PY - 2020 SN - 0022-0957 ER - TY - JOUR AB - Aphids secrete diverse repertoires of effectors into their hosts to promote the infestation process. While 'omics' approaches facilitated the identification and comparison of effector repertoires from a number of aphid species, the functional characterization of these proteins has been limited to dicot (model) plants. The bird cherry-oat aphid Rhopalosiphum padi is a pest of cereal crops, including barley. Here, we extend efforts to characterize aphid effectors with regard to their role in promoting susceptibility to the R. padi-barley interaction. We selected three R. padi effectors based on sequence similarity to previously characterized Myzus persicae effectors and assessed their subcellular localization, expression, and role in promoting plant susceptibility. Expression of R. padi effectors RpC002 and Rp1 in transgenic barley lines enhanced plant susceptibility to R. padi but not M. persicae, for which barley is a poor host. Characterization of Rp1 transgenic barley lines revealed reduced gene expression of plant hormone signalling genes relevant to plant-aphid interactions, indicating that this effector enhances susceptibility by suppressing plant defences in barley. Our data suggest that some aphid effectors specifically function when expressed in host species, and feature activities that benefit their corresponding aphid species. AU - Escudero-Martinez, C.* AU - Rodriguez, P.A. AU - Liu, S.* AU - Santos, P.A.* AU - Stephens, J.* AU - Bos, J.I.B.* C1 - 59747 C2 - 49032 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 2796-2807 TI - An aphid effector promotes barley susceptibility through suppression of defence gene expression. JO - J. Exp. Bot. VL - 71 IS - 9 PB - Oxford Univ Press PY - 2020 SN - 0022-0957 ER - TY - JOUR AB - Date palms are remarkably tolerant to environmental stresses, but the mechanisms involved remain poorly characterized. Leaf metabolome profiling was therefore performed on mature (ML) and young (YL) leaves of 2-year-old date palm seedlings that had been grown in climate chambers that simulate summer and winter conditions in eastern Saudi Arabia. Cultivation under high temperature (summer climate) resulted in higher YL H2O2 leaf levels despite increases in dehydroascorbate reductase (DHAR) activities. The levels of raffinose and galactinol, tricarboxylic acid cycle intermediates, and total amino acids were higher under these conditions, particularly in YL. The accumulation of unsaturated fatty acids, 9,12-octadecadienoic acid and 9,12,15-octadecatrienoic acid, was lower in ML. In contrast, the amounts of saturated tetradecanoic acid and heptadecanoic acid were increased in YL under summer climate conditions. The accumulation of phenolic compounds was favored under summer conditions, while flavonoids accumulated under lower temperature (winter climate) conditions. YL displayed stronger hydration, lower H2O2 levels, and more negative delta C-13 values, indicating effective reactive oxygen species scavenging. These findings, which demonstrate the substantial metabolic adjustments that facilitate tolerance to the high temperatures in YL and ML, suggest that YL may be more responsive to climate change. AU - Du, B.* AU - Kruse, J.* AU - Winkler, J.B. AU - Alfarray, S.* AU - Schnitzler, J.-P. AU - Ache, P.* AU - Hedrich, R.* AU - Rennenberg, H.* C1 - 57242 C2 - 47629 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 5959-5969 TI - Climate and development modulate the metabolome and antioxidative system of date palm leaves. JO - J. Exp. Bot. VL - 70 IS - 20 PB - Oxford Univ Press PY - 2019 SN - 0022-0957 ER - TY - JOUR AB - Cryptochromes (CRYs) and UV RESISTANCE LOCUS 8 (UVR8) photoreceptors perceive UV-A/blue (315-500 nm) and UV-B (280-315 nm) radiation in plants, respectively. While the roles of CRYs and UVR8 have been studied in separate controlled-environment experiments, little is known about the interaction between these photoreceptors. Here, Arabidopsis wild-type Ler, CRYs and UVR8 photoreceptor mutants (uvr8-2, cry1cry2 and cry1cry2uvr8-2), and a flavonoid biosynthesis-defective mutant (tt4) were grown in a sun simulator. Plants were exposed to filtered radiation for 17 d or for 6 h, to study the effects of blue, UV-A, and UV-B radiation. Both CRYs and UVR8 independently enabled growth and survival of plants under solar levels of UV, while their joint absence was lethal under UV-B. CRYs mediated gene expression under blue light. UVR8 mediated gene expression under UV-B radiation, and in the absence of CRYs, also under UV-A. This negative regulation of UVR8-mediated gene expression by CRYs was also observed for UV-B. The accumulation of flavonoids was also consistent with this interaction between CRYs and UVR8. In conclusion, we provide evidence for an antagonistic interaction between CRYs and UVR8 and a role of UVR8 in UV-A perception. AU - Rai, N.* AU - Neugart, S.* AU - Yan, Y.* AU - Wang, F.* AU - Siipola, S.M.* AU - Lindfors, A.V.* AU - Winkler, J.B. AU - Albert, A. AU - Brosché, M.* AU - Lehto, T.* AU - Morales, L.O.* AU - Aphalo, P.J.* C1 - 56082 C2 - 46805 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 4975-4990 TI - How do cryptochromes and UVR8 interact in natural and simulated sunlight? JO - J. Exp. Bot. VL - 70 IS - 18 PB - Oxford Univ Press PY - 2019 SN - 0022-0957 ER - TY - JOUR AB - To investigate the effect of high atmospheric NO concentrations on crop plants and the role of phytoglobins under these conditions, we performed a long-term study on barley 'Golden Promise' wild type (WT), class 1 phytoglobin knockdown (HvPgb1.1-) and class 1 phytoglobin overexpression (HvPgb1.1+) lines. Plants were cultivated with nitrogen-free nutrient solution during the entire growth period and were fumigated with different NO concentration (ambient, 800, 1500, and 3000 ppb). Analysis of fresh weight, stem number, chlorophyll content, and effective quantum yield of PSII showed that NO fumigation promoted plant growth and tillering significantly in the HvPgb1.1+ line. After 80 d of NO fumigation, dry matter weight, spikes number, kernel number, and plant kernel weight were significantly increased in HvPgb1.1+ plants with increasing NO concentration. In contrast, yield decreased in WT and HvPgb1.1- plants the higher the NO level. Application of atmospheric (NO)-N-15 and (NO2)-N-15 demonstrated NO specificity of phytoglobins. N-15 from (NO)-N-15 could be detected in RNA, DNA, and proteins of barley leaves and the N-15 levels were significantly higher in HvPgb1.1+ plants in comparison with HvPgb1.1- and WT plants. Our results demonstrate that overexpression of phytoglobins allows plants to more efficiently use atmospheric NO as N source. AU - Zhang, J. AU - Buegger, F. AU - Albert, A. AU - Ghirardo, A. AU - Winkler, J.B. AU - Schnitzler, J.-P. AU - Hebelstrup, K.H.* AU - Durner, J. AU - Lindermayr, C. C1 - 56420 C2 - 47073 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 4521-4537 TI - Phytoglobin overexpression promotes barley growth in the presence of enhanced level of atmospheric nitric oxide. JO - J. Exp. Bot. VL - 70 IS - 17 PB - Oxford Univ Press PY - 2019 SN - 0022-0957 ER - TY - JOUR AB - This article comments on: Calvo-Begueria L, Rubio MC, Martínez JI, Pérez-Rontomé C, Delgado MJ, Bedmar EJ, Becana M. 2018. Redefining nitric oxide production in legume nodules through complementary insights from electron paramagnetic resonance spectroscopy and specific fluorescent probes. Journal of Experimental Botany 69, 3703-3714. AU - Lindermayr, C. AU - Durner, J. C1 - 53725 C2 - 44958 SP - 3507-3510 TI - Nitric oxide sensor proteins with revolutionary potential. JO - J. Exp. Bot. VL - 69 IS - 15 PY - 2018 SN - 0022-0957 ER - TY - JOUR AB - Nitric oxide (NO) is a key signaling molecule in plant physiology. However, its production in photosynthetic organisms remains partially unresolved. The best characterized NO production route involves the reduction of nitrite to NO via different non-enzymatic or enzymatic mechanisms. Nitrate reductases (NRs), the mitochondrial electron transport chain, and the new complex between NR and NOFNiR (nitric oxide-forming nitrite reductase) described in Chlamydomonas reinhardtii are the main enzymatic systems that perform this reductive NO production in plants. Apart from this reductive route, several reports acknowledge the possible existence of an oxidative NO production in an arginine-dependent pathway, similar to the nitric oxide synthase (NOS) activity present in animals. However, no NOS homologs have been found in the genome of embryophytes and, despite an increasing amount of evidence attesting to the existence of NOS-like activity in plants, the involved proteins remain to be identified. Here we review NO production in plants with emphasis on the presentation and discussion of recent data obtained in this field. AU - Astier, J. AU - Gross, I. AU - Durner, J. C1 - 52548 C2 - 44068 CY - Great Clarendon St, Oxford Ox2 6dp, England SP - 3401-3411 TI - Nitric oxide production in plants: An update. JO - J. Exp. Bot. VL - 69 IS - 14 PB - Oxford Univ Press PY - 2017 SN - 0022-0957 ER - TY - JOUR AB - In natural environments, plants often experience different stresses simultaneously, and adverse abiotic conditions can weaken the plant immune system. Interactome mapping revealed that the LOW SULPHUR UPREGULATED (LSU) proteins are hubs in an Arabidopsis protein interaction network that are targeted by virulence effectors from evolutionarily diverse pathogens. Here we show that LSU proteins are up-regulated in several abiotic and biotic stress conditions, such as nutrient depletion or salt stress, by both transcriptional and post-translational mechanisms. Interference with LSU expression prevents chloroplastic reactive oxygen species (ROS) production and proper stomatal closure during sulphur stress. We demonstrate that LSU1 interacts with the chloroplastic superoxide dismutase FSD2 and stimulates its enzymatic activity in vivo and in vitro. Pseudomonas syringae virulence effectors interfere with this interaction and preclude re-localization of LSU1 to chloroplasts. We demonstrate that reduced LSU levels cause a moderately enhanced disease susceptibility in plants exposed to abiotic stresses such as nutrient deficiency, high salinity, or heavy metal toxicity, whereas LSU1 overexpression confers significant disease resistance in several of these conditions. Our data suggest that the network hub LSU1 plays an important role in co-ordinating plant immune responses across a spectrum of abiotic stress conditions. AU - Garcia-Molina, A.* AU - Altmann, M.* AU - Alkofer, A.* AU - Epple, P.M.* AU - Dangl, J.L.* AU - Falter-Braun, P. C1 - 52368 C2 - 43909 CY - Oxford SP - 1185-1197 TI - LSU network hubs integrate abiotic and biotic stress responses via interaction with the superoxide dismutase FSD2. JO - J. Exp. Bot. VL - 68 IS - 5 PB - Oxford Univ Press PY - 2017 SN - 0022-0957 ER - TY - JOUR AB - Nitric oxide (NO) is a key signaling molecule in plants, regulating a wide range of physiological processes. However, its origin in plants remains unclear. It can be generated from nitrite through a reductive pathway, notably via the action of the nitrate reductase (NR), and evidence suggests an additional oxidative pathway, involving arginine. From an initial screen of potential Arabidopsis thaliana mutants impaired in NO production, we identified copper amine oxidase 8 (CuAO8). Two cuao8 mutant lines displayed a decreased NO production in seedlings after elicitor treatment and salt stress. The NR-dependent pathway was not responsible for the impaired NO production as no change in NR activity was found in the mutants. However, total arginase activity was strongly increased in cuao8 knockout mutants after salt stress. Moreover, NO production could be restored in the mutants by arginase inhibition or arginine addition. Furthermore, arginine supplementation reversed the root growth phenotype observed in the mutants. These results demonstrate that CuAO8 participates in NO production by influencing arginine availability through the modulation of arginase activity. The influence of CuAO8 on arginine-dependent NO synthesis suggests a new regulatory pathway for NO production in plants. AU - Groß, F. AU - Rudolf, E.E. AU - Thiele, B.* AU - Durner, J. AU - Astier, J. C1 - 50900 C2 - 42992 CY - Oxford SP - 2149-2162 TI - Copper amine oxidase 8 regulates arginine-dependent nitric oxide production in Arabidopsis thaliana. JO - J. Exp. Bot. VL - 68 IS - 9 PB - Oxford Univ Press PY - 2017 SN - 0022-0957 ER - TY - JOUR AB - This study aimed to understand the molecular mechanisms of nitrogen dioxide (NO2)-induced toxicity and cell death in plants. Exposure of Arabidopsis to high concentrations of NO2 induced cell death in a dose-dependent manner. No leaf symptoms were visible after fumigation for 1 h with 10 parts per million (ppm) NO2 However, 20 ppm NO2 caused necrotic lesion formation and 30 ppm NO2 complete leaf collapse, which had already started during the 1 h fumigation period. NO2 fumigation resulted in a massive accumulation of nitrite and in protein modifications by S-nitrosylation and tyrosine nitration. Nitric oxide (NO) at 30 ppm did not trigger leaf damage or any of the effects observed after NO2 fumigation. The onset of NO2-induced cell death correlated with NO and hydrogen peroxide (H2O2) signaling and a decrease in antioxidants. NO- and H2O2-accumulating mutants were more sensitive to NO2 than wild-type plants. Accordingly, experiments with specific scavengers confirmed that NO and H2O2 are essential promoters of NO2-induced cell death. Leaf injection of 100 mM nitrite caused an increase in S-nitrosylation, NO, H2O2, and cell death suggesting that nitrite functioned as a mediator of NO2-induced effects. A targeted screening of phytohormone mutants revealed a protective role of salicylic acid (SA) signaling in response to NO2 It was also shown that phytohormones were modulators rather than inducers of NO2-induced cell death. The established experimental set-up is a suitable system to investigate NO2 and cell death signaling in large-scale mutant screens. AU - Kasten, D. AU - Mithöfer, A.* AU - Georgii, E. AU - Lang, H. AU - Durner, J. AU - Gaupels, F. C1 - 52779 C2 - 42885 SP - 6337-6349 TI - Nitrite is the driver, phytohormones are modulators while NO and H2O2 act as promoters of NO2-induced cell death. JO - J. Exp. Bot. VL - 67 IS - 22 PY - 2016 SN - 0022-0957 ER - TY - JOUR AB - In this issue of Journal of Experimental Botany (pages 1505-1517), Ishihara et al. report the identification of a gene responsible for the production of flavonol 3-O-gentiobioside 7-O-rhamnosides by elegantly tickling the ivories of Arabidopsis genetics and genetic resources combined with straightforward metabolite analysis: it is a model case of functional evaluation. AU - Schäffner, A. C1 - 47968 C2 - 39813 CY - Oxford SP - 1203-1204 TI - Flavonoid biosynthesis and Arabidopsis genetics: More good music. JO - J. Exp. Bot. VL - 67 IS - 5 PB - Oxford Univ Press PY - 2016 SN - 0022-0957 ER - TY - JOUR AB - Despite the importance of superoxide dismutases (SODs) in the plant antioxidant defence system little is known about their regulation by post-translational modifications. Here, we investigated the in vitro effects of nitric oxide derivatives on the seven SOD isoforms of Arabidopsis thaliana. S-nitrosoglutathione, which causes S-nitrosylation of cysteine residues, did not influence SOD activities. By contrast, peroxynitrite inhibited the mitochondrial manganese SOD1 (MSD1), peroxisomal copper/zinc SOD3 (CSD3), and chloroplastic iron SOD3 (FSD3), but no other SODs. MSD1 was inhibited by up to 90% but CSD3 and FSD3 only by a maximum of 30%. Down-regulation of these SOD isoforms correlated with tyrosine (Tyr) nitration and both could be prevented by the peroxynitrite scavenger urate. Site-directed mutagenesis revealed that-amongst the 10 Tyr residues present in MSD1-Tyr63 was the main target responsible for nitration and inactivation of the enzyme. Tyr63 is located nearby the active centre at a distance of only 5.26 Å indicating that nitration could affect accessibility of the substrate binding pocket. The corresponding Tyr34 of human manganese SOD is also nitrated, suggesting that this might be an evolutionarily conserved mechanism for regulation of manganese SODs. AU - Holzmeister, C. AU - Gaupels, F. AU - Geerlof, A. AU - Sarioglu, H. AU - Sattler, M. AU - Durner, J. AU - Lindermayr, C. C1 - 42851 C2 - 35818 CY - Oxford SP - 989-999 TI - Differential inhibition of Arabidopsis superoxide dismutases by peroxynitrite-mediated tyrosine nitration. JO - J. Exp. Bot. VL - 66 IS - 3 PB - Oxford Univ Press PY - 2015 SN - 0022-0957 ER - TY - JOUR AU - Kreuzwieser, J.* AU - Scheerer, U.* AU - Kruse, J.* AU - Burzlaff, T.* AU - Honsel, A.* AU - Alfarraj, S.* AU - Georgiev, P.* AU - Schnitzler, J.-P. AU - Ghirardo, A. AU - Kreuzer, I.* AU - Hedrich, R.* AU - Rennenberg, H.* C1 - 46296 C2 - 37496 CY - Oxford SP - 3429 TI - Corrigendum: The Venus flytrap attracts insects by the release of volatile organic compounds. JO - J. Exp. Bot. VL - 66 IS - 11 PB - Oxford Univ Press PY - 2015 SN - 0022-0957 ER - TY - JOUR AB - Plants emit a great variety of volatile organic compounds (VOCs) that can actively participate in plant growth and protection against biotic and abiotic stresses. VOC emissions are strongly dependent on environmental conditions; the greatest ambiguity is whether or not the predicted change in climate will influence and modify plant-pest interactions that are mediated by VOCs. The constitutive and induced emission patterns between plant genotypes, species, and taxa are highly variable and can be used as pheno(chemo)typic markers to distinguish between different origins and provenances. In recent years significant progress has been made in molecular and genetic plant breeding. However, there is actually a lack of knowledge in functionally linking genotypes and phenotypes, particularly in analyses of plant-environment interactions. Plant phenotyping, the assessment of complex plant traits such as growth, development, tolerance, resistance, etc., has become a major bottleneck, and quantitative information on genotype-environment relationships is the key to addressing major future challenges. With increasing demand to support and accelerate progress in breeding for novel traits, the plant research community faces the need to measure accurately increasingly large numbers of plants and plant traits. In this review article, we focus on the promising outlook of VOC phenotyping as a fast and non-invasive measure of phenotypic dynamics. The basic principle is to define plant phenotypes according to their disease resistance and stress tolerance, which in turn will help in improving the performance and yield of economically relevant plants. AU - Niederbacher, B. AU - Winkler, J.B. AU - Schnitzler, J.-P. C1 - 44867 C2 - 37180 SP - 5403-5416 TI - Volatile organic compounds as non-invasive markers for plant phenotyping. JO - J. Exp. Bot. VL - 66 IS - 18 PY - 2015 SN - 0022-0957 ER - TY - JOUR AB - Does Dionaea muscipula, the Venus flytrap, use a particular mechanism to attract animal prey? This question was raised by Charles Darwin 140 years ago, but it remains unanswered. This study tested the hypothesis that Dionaea releases volatile organic compounds (VOCs) to allure prey insects. For this purpose, olfactory choice bioassays were performed to elucidate if Dionaea attracts Drosophila melanogaster. The VOCs emitted by the plant were further analysed by GC-MS and proton transfer reaction-mass spectrometry (PTR-MS). The bioassays documented that Drosophila was strongly attracted by the carnivorous plant. Over 60 VOCs, including terpenes, benzenoids, and aliphatics, were emitted by Dionaea, predominantly in the light. This work further tested whether attraction of animal prey is affected by the nutritional status of the plant. For this purpose, Dionaea plants were fed with insect biomass to improve plant N status. However, although such feeding altered the VOC emission pattern by reducing terpene release, the attraction of Drosophila was not affected. From these results it is concluded that Dionaea attracts insects on the basis of food smell mimicry because the scent released has strong similarity to the bouquet of fruits and plant flowers. Such a volatile blend is emitted to attract insects searching for food to visit the deadly capture organ of the Venus flytrap. AU - Kreuzwieser, J.* AU - Scheerer, U.* AU - Kruse, J.* AU - Burzlaff, T.* AU - Honsel, A.* AU - Alfarraj, S.* AU - Georgiev, P.* AU - Schnitzler, J.-P. AU - Ghirardo, A. AU - Kreuzer, I.* AU - Hedrich, R.* AU - Rennenberg, H.* C1 - 29288 C2 - 33323 CY - Oxford SP - 755-766 TI - The Venus flytrap attracts insects by the release of volatile organic compounds. JO - J. Exp. Bot. VL - 65 IS - 2 PB - Oxford Univ Press PY - 2014 SN - 0022-0957 ER - TY - JOUR AB - Systemic acquired resistance (SAR) is a form of inducible disease resistance that depends on salicylic acid and its upstream regulator ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1). Although local Arabidopsis thaliana defence responses activated by the Pseudomonas syringae effector protein AvrRpm1 are intact in eds1 mutant plants, SAR signal generation is abolished. Here, the SAR-specific phenotype of the eds1 mutant is utilized to identify metabolites that contribute to SAR. To this end, SAR bioassay-assisted fractionation of extracts from the wild type compared with eds1 mutant plants that conditionally express AvrRpm1 was performed. Using high-performance liquid chromatography followed by mass spectrometry, systemic immunity was associated with the accumulation of 60 metabolites, including the putative SAR signal azelaic acid (AzA) and its precursors 9-hydroperoxy octadecadienoic acid (9-HPOD) and 9-oxo nonanoic acid (ONA). Exogenous ONA induced SAR in systemic untreated leaves when applied at a 4-fold lower concentration than AzA. The data suggest that in planta oxidation of ONA to AzA might be partially responsible for this response and provide further evidence that AzA mobilizes Arabidopsis immunity in a concentration-dependent manner. The AzA fragmentation product pimelic acid did not induce SAR. The results link the C9 lipid peroxidation products ONA and AzA with systemic rather than local resistance and suggest that EDS1 directly or indirectly promotes the accumulation of ONA, AzA, or one or more of their common precursors possibly by activating one or more pathways that either result in the release of these compounds from galactolipids or promote lipid peroxidation. AU - Wittek, F. AU - Hoffmann, T.* AU - Kanawati, B. AU - Bichlmeier, M. AU - Knappe, C. AU - Wenig, M. AU - Schmitt-Kopplin, P. AU - Parker, J.E.* AU - Schwab, W.* AU - Vlot, A.C. C1 - 31834 C2 - 34878 CY - Oxford SP - 5919-5931 TI - Arabidopsis ENHANCED DISEASE SUSCEPTIBILITY1 promotes systemic acquired resistance via azelaic acid and its precursor 9-oxo nonanoic acid. JO - J. Exp. Bot. VL - 65 IS - 20 PB - Oxford Univ Press PY - 2014 SN - 0022-0957 ER - TY - JOUR AB - Phenology ranks among the best ecosystem processes for fingerprinting climate change since temperature explains a high percentage of the interannual or spatial variation in phenological onset dates. However, roles of other environmental variables, such as foliar nutrient concentrations, are far from adequately understood. This observational study examined the effects of air temperature and 11 nutrients on spring phenology of Betula pendula Roth (birch) along an urban-rural gradient in Munich, Germany, during the years 2010/2011. Moreover, the influence of temperature, nutrients, and air pollutants (NO2 and O3) on the amounts of pollen and catkin biomass in 2010 was evaluated. In addition to the influence of higher temperatures advancing phenological onset dates, higher foliar concentrations of potassium, boron, zinc, and calcium were statistically significantly linked to earlier onset dates. Since flushing of leaves is a turgor-driven process and all the influential nutrients are involved in cell extension, membrane function, and stability, there might be a reasonable physiological interpretation of the observed association. The amounts of pollen were negatively correlated with temperature, atmospheric NO2, and foliar iron concentration, suggesting that these variables restrict pollen production. The results of this study suggested an influence of nutritional status on both phenology and pollen production. The interaction of urbanization and climate change should be considered in the assessment of the impact of global warming on ecosystems and human health. AU - Jochner, S.* AU - Höfler, J.* AU - Beck, I. AU - Göttlein, A.* AU - Ankerst, D.P.* AU - Traidl-Hoffmann, C. AU - Menzel, A.* C1 - 48564 C2 - 41186 SP - 2081-2092 TI - Nutrient status: A missing factor in phenological and pollen research? JO - J. Exp. Bot. VL - 64 IS - 7 PY - 2013 SN - 0022-0957 ER - TY - JOUR AB - Flavonols, phenylalanine-derived secondary metabolites, have protective and regulatory functions in plants. In Arabidopsis thaliana, they are consecutively glycosylated at their 3-OH and 7-OH groups. UGT78D1 and UGT78D2 are the major flavonol 3-O-glycosyltransferases in Arabidopsis leaves. The ugt78d1 ugt78d2 double mutant, which was strongly compromised in the initial 3-O-glycosylation, showed a severe and specific repression of flavonol biosynthesis, retaining only one-third of the wild-type level. This metabolic phenotype was associated with a repressed transcription of several flavonol biosynthetic genes including the committed step chalcone synthase [(CHS) or TRANSPARENT TESTA 4 (TT4)]. Furthermore, the committed step of the upstream, general phenylpropanoid pathway, phenylalanine ammonia-lyase (PAL), was down-regulated in its enzyme activity and in the transcription of the flavonol-related PAL1 and PAL2. However, a complete blocking of flavonoid biosynthesis at CHS released PAL inhibition in a tt4 ugt78d1 ugt78d2 line. PAL activity was even enhanced in the flavonol synthase 1 mutant, which compromises the final formation of flavonol aglycones. The dependence of the PAL feedback inhibition on flavonols was confirmed by chemical complementation of tt4 ugt78d1 ugt78d2 using naringenin, a downstream flavonoid intermediate, which restored the PAL repression. Although aglycones were not analytically detectable, this study provides genetic evidence for a novel, flavonol-dependent feedback inhibition of the flavonol biosynthetic pathway and PAL. It was conditioned by the compromised flavonol-3-O-conjugation and a decrease in flavonol content, yet dependent on a residual, flavonol synthase 1 (FLS1)-related capacity to form flavonol aglycones. Thus, this regulation would not react to a reduced metabolic flux into flavonol biosynthesis, but it might prevent the accumulation of non-glycosylated, toxic flavonols. AU - Yin, R. AU - Messner, B. AU - Faus-Kessler, T. AU - Hoffmann, T.* AU - Schwab, W.* AU - Hajirezaei, M.-R.* AU - von Saint Paul, V. AU - Heller, W. AU - Schäffner, A. C1 - 7482 C2 - 29742 SP - 2465-2478 TI - Feedback inhibition of the general phenylpropanoid and flavonol biosynthetic pathways upon a compromised flavonol-3-O-glycosylation. JO - J. Exp. Bot. VL - 63 IS - 7 PB - Oxford Univ. Press PY - 2012 SN - 0022-0957 ER - TY - JOUR AB - Due to the physico-chemical similarities of caesium (Cs(+)) to potassium (K(+)) on the one hand and strontium (Sr(2+)) to calcium (Ca(2+)) on the other hand, both elements can easily be taken up by plants and thus enter the food chain. This could be detrimental when radionuclides such as (137)Cs and (90)Sr are involved. In this study, both genetic and physiological aspects of Cs(+) and Sr(2+) accumulation in Arabidopsis thaliana were investigated using 86 Arabidopsis accessions and a segregating F(2) population of the low Cs(+) accumulating Sq-1 (Ascot, UK) crossed with the high uptaking Sorbo (Khurmatov, Tajikistan). Hydroponically grown plants were exposed to subtoxic levels of Cs(+) and Sr(2+) using radioactive isotopes as tracers. In the natural accessions shoot concentration of Cs(+) as well as Sr(2+) varied about 2-fold, whereas its heritability ranged for both ions between 0.60 and 0.73. Shoot accumulation of Cs(+) and Sr(2+) could be compromised by increasing concentrations of their essential analogues K(+) and Ca(2+), respectively, causing a reduction of up to 80%. In the case of the segregating F(2)/F(3) population Sq-1×Sorbo, this study identified several QTL for the trait Cs(+) and Sr(2+) accumulation, with main QTL on chromosomes 1 and 5. According to the correlation and discrimination surveys combined with QTL-analysis Cs(+) and Sr(2+) uptake seemed to be mediated mostly via non-selective cation channels. A polymorphism, affecting amino acids close to the K(+)-pore of one candidate, CYCLIC-NUCLEOTIDE-GATED CHANNEL 1 (CNGC1), was identified in Sorbo and associated with high Cs(+) concentrating accessions. AU - Kanter, U. AU - Hauser, A.R. AU - Michalke, B. AU - Dräxl, S.J. AU - Schäffner, A. C1 - 5857 C2 - 27425 SP - 3995-4009 TI - Caesium and strontium accumulation in shoots of Arabidopsis thaliana: Genetic and physiological aspects. JO - J. Exp. Bot. VL - 61 IS - 14 PB - Oxford Univ. Press PY - 2010 SN - 0022-0957 ER - TY - JOUR AB - Due to its high reactivity and its ability to diffuse and permeate the cell membrane, nitric oxide (NO) and its exchangeable redox-activated species are unique biological messengers in animals and in plants. Although an increasing number of reports indicate that NO is an essential molecule in several physiological processes, there is not a clear picture of its method of action. Studies on the transcriptional changes induced by NO permitted identification of genes involved in different functional processes such as signal transduction, defence and cell death, transport, basic metabolism, and reactive oxygen species (ROS) production and degradation. The co-expression of these genes can be explained by the co-operation of a set of transcription factors that bind a common region in the promoter of the regulated genes. The present report describes the search for a common transcription factor-binding site (TFBS) in promoter regions of NO-regulated genes, based on microarray analyses. Using Genomatix Gene2Promotor and MatInspector, eight families of TFBSs were found to occur at least 15% more often in the promoter regions of the responsive genes in comparison with the promoter regions of 28,447 Arabidopsis control genes. Most of these TFBSs, such as ocs element-like sequences and WRKY, have already been reported to be involved in particular stress responses. Furthermore, the promoter regions of genes involved in jasmonic acid (JA) biosynthesis were analysed for a common TFBS module, since some genes responsible for JA biosynthesis are induced by NO, and an interaction between NO and JA signalling has already been described. AU - Palmieri, M.C. AU - Sell, S. AU - Huang, X. AU - Scherf, M.* AU - Werner, T.* AU - Durner, J. AU - Lindermayr, C. C1 - 4038 C2 - 25329 SP - 177-186 TI - Nitric oxide-responsive genes and promoters in Arabidopsis thaliana: A bioinformatics approach. JO - J. Exp. Bot. VL - 59 IS - 2 PB - Oxford Univ. Press PY - 2008 SN - 0022-0957 ER - TY - JOUR AB - Field-grown sugar beets were analysed for morphological characters, sucrose content, and reproducible transcript profiles by macroarray analyses with 11 520 unique sugar-beet cDNA targets in two different years. Seasonal differences were partly compensated by expressing sampling dates as thermal time. During early beet development the number of cambial rings, root length, and sucrose concentration had already achieved >40% of their final values. Sucrose levels rose from 10% to 17% over the thermal time of 1300–1400 °Cd with only small changes later when lower concentrations were restricted to the exterior zone at the minimum of the spatial sucrose gradient through the beet. The number of leaves and root diameter followed the same temporal growth pattern, but mass increased until beet maturity at around 2000 °Cd. Cluster analysis identified 543 transcripts with reproducible preferential expression between 1300–1400 °Cd, and 170 showing the highest transcript levels later. In maturing beets, 373 transcripts were over-represented in the inner zone and 148 in the outer zone. During early development, genes involved in cytoskeletal reorganization and transport processes showed the highest transcript levels. Cell wall biogenesis-, defence-, stress-, and degradation-related transcripts were identified in all samples, and associated with pathogen attack during late development and in the outer zone. Candidates with potential roles in carbohydrate metabolism appeared to serve anaplerotic functions by converting excess intermediates to sucrose production. Transcripts preferentially occurring in sucrose-accumulating young beet cells and newly generated peripheral cells of mature beets are discussed as potential breeding targets to improve sink strength and growth. AU - Bellin, D.* AU - Schulz, B.* AU - Soerensen, T.R.* AU - Salamini, F.* AU - Schneider, K. C1 - 3135 C2 - 24401 SP - 699-715 TI - Transcript profiles at different growth stages and tap-root zones identify correlated developmental and metabolic pathways of sugar beet. JO - J. Exp. Bot. VL - 58 IS - 3 PB - Oxford Univ. Press PY - 2007 SN - 0022-0957 ER - TY - JOUR AB - Four Methylobacterium extorquens strains were isolated from strawberry (Fragariaxananassa cv. Elsanta) leaves, and one strain, called ME4, was tested for its ability to promote the growth of various plant seedlings. Seedling weight and shoot length of Nicotiana tabacum, Lycopersicon esculentum, Sinapis alba, and Fragaria vesca increased significantly in the presence of the pink-pigmented facultative methylotroph (PPFM), but the germination behaviour of seeds from six other plants was not affected. The cell-free supernatant of the bacterial culture stimulated germination, suggesting the production of a growth-promoting agent by the methylotroph. Methanol emitted from N. tabacum seedlings, as determined by proton-transfer-reaction mass spectrometry (PTR-MS), ranged from 0.4 to 0.7 ppbv (parts per billion by volume), while significantly lower levels (0.005 to 0.01 ppbv) of the volatile alcohol were measured when the seedlings were co-cultivated with M. extorquens ME4, demonstrating the consumption of the gaseous methanol by the bacteria. Additionally, by using cells of the methylotrophic yeast Pichia pastoris transformed with the pPICHS/GFP vector harbouring a methanol-sensitive promoter in combination with the green fluorescence protein (GFP) reporter gene, stomata were identified as the main source of the methanol emission on tobacco cotyledons. Methylobacterium extorquens strains can nourish themselves using the methanol released by the stomata and release an agent promoting the growth of the seedlings of some crop plants. AU - Abanda-Nkpwatt, D.* AU - Müsch, M. AU - Tschiersch, J. AU - Boettner, M.* AU - Schwab, W.* C1 - 5823 C2 - 24310 SP - 4025-4032 TI - Molecular interaction between Methylobacterium extorquens and seedling: Growth promotion, methanol consumption and localization of the methanol emission site. JO - J. Exp. Bot. VL - 57 IS - 15 PB - Oxford Univ. Press PY - 2006 SN - 0022-0957 ER - TY - JOUR AB - There is increasing evidence that nitric oxide (NO), which was first identified as a unique diffusible molecular messenger in animals, plays an important role in diverse physiological processes in plants. Recent progress that has deepened our understanding of NO signalling functions in plants, with special emphasis on defence signalling, is discussed here. Several studies, based on plants with altered NO-levels, have recently provided genetic evidence for the importance of NO in gene induction. For a general overview of which gene expression levels are altered by NO, two studies, involving large-scale transcriptional analyses of Arabidopsis thaliana using custom-made or commercial DNA-microarrays, were performed. Furthermore, a comprehensive transcript profiling by cDNA-amplification fragment length polymorphism (AFLP) revealed a number of Arabidopsis thaliana genes that are involved in signal transduction, disease resistance and stress response, photosynthesis, cellular transport, and basic metabolism. In addition, NO affects the expression of numerous genes in other plant species such as tobacco or soybean. The NO-dependent intracellular signalling pathway(s) that lead to the activation or suppression of these genes have not yet been defined. Several lines of evidence point to an interrelationship between NO and salicylic acid (SA) in plant defence. Recent evidence suggests that NO also plays a role in the wounding/jasmonic acid (JA) signalling pathway. NO donors affect both wounding-induced H2O2 synthesis and wounding- or JA-induced expression of defence genes. One of the major challenges ahead is to determine how the correct specific response is evoked, despite shared use of the NO signal and, in some cases, its downstream second messengers. AU - Grün, S. AU - Lindermayr, C. AU - Sell, S. AU - Durner, J. C1 - 1925 C2 - 23583 SP - 507-516 TI - Nitric oxide and gene regulation in plants. JO - J. Exp. Bot. VL - 57 IS - 3 PB - Oxford Univ. Press PY - 2006 SN - 0022-0957 ER - TY - JOUR AB - Salt stress is known to reduce root hydraulic conductivity and growth. To examine a concomitant regulation of aquaporins, the expression of the maize MIP gene family in response to NaCl was analysed by DNA array hybridization. Plants responded differentially to 100 versus 200 mM NaCl treatments. Leaf water content was reduced rapidly and persistently after the application of 200 mM NaCl in contrast to 100 mM NaCl. Endogenous ABA strongly accumulated in roots after 2 h; it remained at a highly elevated level for 48 h after the addition of 200 mM NaCl, but rapidly declined in plants treated with 100 mM NaCl, indicating an early recovery from water deficit. Interestingly, 2 h after the addition of 100 mM NaCl, when maize regained the osmotic potential allowing water uptake, three highly expressed, specific isoforms ZmPIP1;1, ZmPIP1;5, and ZmPIP2;4 were transiently induced. They were preferentially transcribed in the outer root tissue suggesting a role in cellular water transport. None of the ZmTIP genes was altered. By contrast, after the addition of 200 mM NaCl these responses were missing. Instead, multiple ZmPIP and ZmTIP genes were repressed by 200 mM NaCl after 24 h. After 48 h, deregulations were overridden in both cases indicating homeostasis. ABA (1 mu M) exogenously applied to the roots transiently induced ZmPIP2;4 similar to 100 mM NaCl as well as ZmPIP1;2. Thus, the early induction of ZmPIP2;4 by NaCl may be mediated by ABA. Previously, an increase in root hydraulic conductivity had been observed upon ABA application. By contrast, 100 mu M ABA led to a complete, possibly non-specific repression of all detected ZmPIP and ZmTIP genes after 24 h. AU - Zhu, C. AU - Schraut, D.* AU - Hartung, W.* AU - Schäffner, A. C1 - 3606 C2 - 23031 SP - 2971-2981 TI - Differential responses of maize MIP genes to salt stress and ABA. JO - J. Exp. Bot. VL - 56 IS - 421 PB - Oxford Univ. Press PY - 2005 SN - 0022-0957 ER - TY - JOUR AU - Grams, T.E.E. AU - Thiel, S. C1 - 22108 C2 - 20784 SP - 1475-1483 TI - High light-induced switch from C3-photosynthesis to Crassulacean acid metabolism is mediated by UV-A/blue light. JO - J. Exp. Bot. VL - 53 PY - 2002 SN - 0022-0957 ER - TY - JOUR AU - Baiges, I.* AU - Schäffner, A. AU - Mas, A.* C1 - 21840 C2 - 20053 SP - 1949-1951 TI - Eight cDNA encoding putative aquaporins in Vitis hybrid Richter-110 and their differential expression. JO - J. Exp. Bot. VL - 52 PY - 2001 SN - 0022-0957 ER - TY - JOUR AU - Vranova, E.* AU - Langebartels, C. AU - van Montagu, M.* AU - Inzé, D.* AU - van Camp, W.* C1 - 21808 C2 - 20010 SP - 1763-1764 TI - Oxidative stress, heat shock and drought differentially affect expression of a tobacco protein phosphatase 2C1. JO - J. Exp. Bot. VL - 51 PY - 2000 SN - 0022-0957 ER - TY - JOUR AB - Mineral deficiencies can reduce the absorption and translocation of the urea herbicide [14C]-buturon and its metabolites in wheat. The efflux of [14C]buturon and its metabolites from mineral-deficient plants was increased as compared to normal-grown plants.The metabolism rate of herbicide in the roots of normal-grown plants increased for 24 h, then decreased again, whereas in shoots a continuous increase was observed for 7 d; at this time, the metabolism rate was 25.6 per cent of the radioactivity present in the roots and 23.7 per cent in the shoots. In the nutrient-deficient plants, the metabolism of buturon was significantly increased as compared to the plants grown in normal medium. In the N-deficient nutrient medium, the ratio of metabolites to parent compound was higher than in the complete medium.Four groups of metabolites were observed in plants: a small group of carbamates (metabolite group I), a group of mainly unstable compounds decreasing rapidly in roots (II), a group comprising, among others, p-chloroacetanilide (III), and a group of conjugates (IV); the groups III and IV increased continuously during 7 d. The metabolites were isolated through column and thin layer chromatography and identified by comparison with reference compounds and combined gas chromatography/mass spectrometry analysis. AU - Haque, A.U. AU - Weisgerber, I. AU - Klein, W. C1 - 41793 C2 - 35684 SP - 468-479 TI - Absorption, efflux, and metabolism of the herbicide [14C]Buturon as affected by plant nutrition. JO - J. Exp. Bot. VL - 28 IS - 2 PY - 1977 SN - 0022-0957 ER -