Hard red spring wheat (HRSW) is an important market class of wheat in North America. We genotyped 1,013 HRSW lines representing a century of breeding using SNP array and targeted KASP genotyping to assess changes in genetic diversity and Rht genes. Our results suggest that early breeding efforts broadened an initially narrow gene pool derived from few founders and subsequently maintained genetic diversity. Analysis of Rht genes revealed that Rht-D1b was the predominant semi-dwarf allele following the introduction of gibberellic acid (GA)-insensitive alleles (Rht-B1b and Rht-D1b) during the Green Revolution of the 1960s. However, wheat scab epidemics of 1990s coincided with most breeding programs shifting to Rht-B1b. Adoption of Rht-B1b and Rht-D1b remains low in some regions of the Great Plains, where breeding programs have utilized alternative dwarfing GA-sensitive alleles at Rht24 and Rht25 loci. We analyzed the effect of Rht genes on plant height in the HRSW growing region and found that the effect of Rht-B1b and Rht-D1b diminishes in drier environments. Combining dwarfing alleles at Rht24 and Rht25 was associated with a significant reduction in plant height even in the absence of Green Revolution genes. This study offers insights to guide future breeding strategies for HRSW in North America.
The cellulose microfibrils of land plants are synthesized by two families of enzymes, Cellulose Synthase (CESA) and CESA-Like-D (CSLD). Both form rosette Cellulose Synthesis Complexes (CSCs), which appear as hexagonal groups of six particles with freeze fracture transmission electron microscopy. Throughout the green plant lineage, CSC morphology is correlated with cellulose microfibril structure and properties. Charophyte green algae (CGA) have CESAs, CSLDs, and/or CESA/CSLD-like enzymes from which the other two families likely evolved, and most have rosette CSCs. The apparent exception is Coleochaete, previously reported to have unique octagonal CSCs. Using a specimen preparation method that promotes periclinal fractures, we show that Coleochaete has typical six-particle rosette CSCs consistent with expression of CSLD genes, thus resolving a long-standing anomaly. Coleochaetophyceae also express CESA/CSLD-like genes, but no CESAs were detected in 27 Coleochaete and Chaetosphaeridium transcriptomes. The phylogenetic distribution and exon-intron structure of CESAs, CSLDs, and their CESA/CSLD-like common ancestors are consistent with an evolutionary history that included losses and gains of genes and introns, with implications for the divergence and functional specialization of the CESA and CSLD families. Together, these findings help clarify the structural basis of cellulose microfibril synthesis in CGA and the evolution of cellulose synthases in plants.
Glutaredoxins (GRXs) constitute a distinct family within the large thioredoxin superfamily. Based on the historic order of discoveries and structural similarities, GRXs were originally annotated as glutathione-dependent oxidoreductases with a CxxC active site motif. These prototypical GRXs are now clustered as class I. Later, it was discovered that some GRXs, particularly those with the highly conserved active site motif CGFS, coordinate iron-sulfur clusters and exhibit little or no oxidoreductase activity. Throughout the course of evolution across kingdoms, the CGFS GRXs form the most highly conserved class II. Compared to non-plant species, the GRX family in spermatophytes has undergone significant enlargement and diversification, resulting in typically more than 30 isoforms that are separated into four classes. This expansion is largely due to the evolution of new plant-specific class III GRXs or ROXYs, characterized by a central CCxx active site motif. The increasing number of GRX copies in the genome, coupled with the modification of domains and addition of domains with different functions, has resulted in the functional diversification of plant GRXs. In this review, we aim to provide an overview of the established and emerging roles of GRXs in plant metabolism.
Tocochromanols, including tocopherols and tocotrienols, encompass a group of lipid antioxidants that are synthesized in chloroplasts of photosynthetic organisms. Tocochromanols are essential for mammals, because they provide vitamin E activity. In plants, tocochromanols can scavenge reactive oxygen species derived from photosynthesis. While most dicot plants including Arabidopsis thaliana produce tocopherols with a saturated side chain, tocotrienols carrying an unsaturated side chain are found in many monocot plants. Here, we present an overview on the current knowledge about the biosynthesis of tocopherols, with a focus on the origin of the head group and side chain precursors, and the regulation of tocopherol synthesis by abiotic stress and phytohormones. The chromanol headgroup is derived from tyrosine which is synthesized via the shikimate pathway, while the phytyl side chain originates from chlorophyll turnover. Tocopherol synthesis is regulated during different abiotic stress conditions, including high light, drought, heat, cold and salt stress. Furthermore, different phytohormones like jasmonate, abscisic acid, gibberellins, brassinosteroids and salicylate are involved in the regulation of tocopherol synthesis. The control of stress- and phytohormone-dependent tocopherol synthesis is mostly based on the regulation on the transcriptional level of key genes of tocopherol synthesis.
Specialized metabolites mediate diverse plant-environment interactions. Recent work has begun to enzymatically characterize entire plant specialized metabolic pathways; however, little is known about how different pathway components organize and interact within the cell. Here we use acylsugars - a class of specialized metabolites - to explore metabolic complex formation. In Solanum lycopersicum (tomato) four trichome-localized acylsugar acyltransferases (SlASAT1-4) sequentially add acyl chains to a sucrose core leading to accumulation of tri and tetraacylated sucroses. Confocal microscopy demonstrates that tomato ASATs localize to distinct subcellular locations, including the mitochondria, cytosol, and endoplasmic reticulum. To explore pairwise protein-protein interactions in acylsugar biosynthesis, we used various techniques relying on different interaction principles, including co-immunoprecipitation, split luciferase assays, and bimolecular fluorescence complementation all demonstrating pairwise SlASAT interactions. Following transient expression of SlASAT1-4 in Nicotiana benthamiana, we were able to pull down a complex consisting of SlASAT1-4, which was confirmed through proteomics. Size exclusion chromatography of the SlASAT pulldown suggests a heteromultimeric complex of around 300 kDa. This study sheds light on the metabolic coordination of acylsugar biosynthesis through formation of a metabolic complex enabling production of chemical defenses.
Increasing temperature fluctuations threaten crop productivity worldwide, emphasizing the need for a deeper understanding of plant adaptation to such extremes. Lipids are fundamental biological molecules that furnish structural, metabolic, and regulatory roles in plant growth and development, and responses to environmental stresses. The potential of lipids as key targets for crop improvement under changing climates is emerging. This systematic review and meta-analysis are comprehensive syntheses of current knowledge on plant lipidome responses to heat and cold stresses. The analysis reveals conserved lipidomic responses to heat and cold stresses across plant species, tissue types, and growth stages. The decreased levels of lipids with relatively smaller head groups (e.g., MGDG, PE) that promote membrane bilayer structure, a decrease in unsaturation index in membrane lipids, and sequestration of polyunsaturated acyl chains into neutral lipids (e.g., TG) emerged as conserved strategies for heat adaptation. Also, very long-chain fatty acids were identified as important in heat stress adaptation, as their presence is likely to counteract excessive membrane fluidity caused by high temperature and to maintain membrane stability under heat stress. Under cold stress, the levels of membrane lipids containing polyunsaturated acyl chains were elevated, likely as an adaptive shift favoring more fluid, flexible membranes. Further, the levels of bilayer-forming lipids (e.g., DGDG) increased and non-bilayer-forming lipids (e.g., MGDG) decreased. Overall, this paper synthesizes knowledge of lipidome remodeling in plants and its role in resilience to temperature stress, identifying priority areas for future research to support climate-resilient agriculture.
Plant oxylipins include the jasmonates, lipid-derived hormones that control growth-defense trade-offs. In tracheophytes, (3R, 7S)-jasmonoyl-L-isoleucine (JA-Ile) is the principal bioactive ligand that assembles the COI1-JAZ co-receptor together with inositol polyphosphates, leading to JAZ degradation and transcriptional reprogramming. By contrast, bryophytes employ dn-cis/iso-OPDA and related species, revealing evolutionary diversity in ligand identity and receptor matching. This review synthesizes chemical perspectives on jasmonate signaling. First, we outline the "molecular-glue" logic of COI1-JAZ assembly and the current structural gap beyond Arabidopsis that limits lineage-level, structure-guided discussion. Second, we summarize multilayered metabolic circuits that sculpt signal intensity, duration and spatial distribution: oxidation of JA-Ile to 12-OH- and 12-COOH-JA-Ile; hydrolysis; and hydroxylation of the JA backbone. Notably, 12-OH-JA-Ile can function as a weak and "biased" agonist, whereas 12-COOH-JA-Ile is receptor-silent; in Marchantia, dn-iso-OPDA is chiefly inactivated by conjugation with amino acids, paralleling auxin logic. Third, we review evidence for co-evolution of ligands with COI1/JAZ components across land plants. Finally, we highlight the design of COI1-JAZ subtype-selective agonists and antagonists-often based on coronatine scaffolds-that preferentially recruit specific JAZ proteins to promote ERF/ORA outputs while sparing MYC-branch responses. These chemical levers suggest practical routes to amplify defense with reduced growth costs, offering opportunities for stress-resilient crop improvement.
Mitochondria are central to plant metabolism, yet the diversity of mechanisms plants use to cope with mitochondrial stress and its implications in cellular signaling are not fully understood. In this study, we analyzed Arabidopsis noxy (nonresponding to oxylipins) mutants affected in 9-HOT (9(S)-hydroxy-10,12,15-octadecatrienoic acid) signaling, mitochondrial function and ethylene (ET) signaling to dissect plant responses to a range of mitochondrial stresses, including inhibitors of all electron transport chain complexes and mitochondrial translation. All noxy mutants showed resistance to antimycin A (AA), implicating Complex III and 9-HOT signaling in mitochondrial stress adaptation. Notably, noxy22/eto1-14, an ET overproducer mutant, displayed resistance to all tested inhibitors independently of the canonical mitochondrial retrograde pathway mediated by ANAC017. We found similar results in eto1-5 and eto1-13 alleles, thus sustaining a role for ET in mitochondrial protection. Histochemical and RNA-seq analysis revealed that AA induced ANAC017-regulated genes early and independently of ET signaling whereas EIN2 contributed in later induction of AA-associated immune responses. EIN2 was required for full activation of AA-induced resistance against the biotrophic pathogen Hyaloperonospora arabidopsidis, but not against the necrotroph Plectosphaerella cucumerina. Collectively, our findings point to a complex network that coordinates distinct but overlapping responses to mitochondrial dysfunction and integrates them into broader stress pathways.
This review focuses on studies related to aerenchymal tissues and their functions in mangrove trees, particularly from the perspective of trees' hypoxic tolerance, which is crucial for understanding ecophysiological mechanisms underlying mangrove tree growth and evaluating functions of mangrove ecosystems. Mangrove trees possess a well-developed aeration system connecting aerial roots to submerged roots. This internal aeration structure connecting organs already exists during the seedling stage before aerial roots fully develop. Root porosity ranges from 6% to 60%, exhibiting species-specific characteristics. This variation likely correlates with the anaerobic conditions of each species' habitat. The internal aeration structure is open to the atmosphere via lenticels on the aerial roots and stem surface and via cork warts on the abaxial leaf surface, allowing the diffusion of oxygen, nitrogen, and methane driven by concentration gradients. Despite this extensive ventilation system, prolonged waterlogging at high tide inevitably leads to root hypoxia, causing anaerobic fermentation and damage induced by reactive oxygen species. As a tolerance mechanism against these stresses, mangrove trees possess antioxidant systems, though tolerance capacity varies among species. Some of the oxygen delivered to the underground part leaks into the soil through the root surface. This creates a thin oxidative layer on the root surface, reducing the uptake of phytotoxic substances and promoting the nitrification process in anaerobic soil. In addition to hypoxia caused by waterlogging, salt stress is a critical factor requiring adaptation on tidal flats. The energy demand required to cope with salt stress may increase oxygen demand through respiration, but the respiration rate of mangrove roots likely decreases under salt stress because the salt excretion process in mangrove roots is entirely physical in nature.
Plants face the core challenge of balancing growth and defense through fine-tuned metabolic regulation, which hinges on the coordinated biosynthesis of specialized metabolites such as isoprenoids and phenylpropanoids. This review integrates current insights into the dynamic interplay between these pathways, highlighting their role as a unified adaptive response to abiotic stresses, including drought, light, salinity, heavy metals, nutrient deficiency, altitude, temperature extremes, and combined stressors. Their interaction establishes a context-dependent regulatory network, characterized by both synergistic and antagonistic effects, potentially driven by competition for the shared precursor phosphoenolpyruvate. This metabolic node demands dynamic resource allocation, inherently generating trade-offs that shape its complex regulatory relationship. Hierarchical transcriptional networks, involving specific of transcription factors families, further refine this cross-pathway communication. By integrating environmental and developmental cues, these networks fine-tune metabolic output to achieve coordinated physiological responses. The crosstalk between isoprenoid and phenylpropanoid pathways is a key regulatory node for metabolic plasticity, enabling plants to deploy robust, multi-layered defenses. Deciphering the systemic signals and regulatory hubs governing these pathways is critical for the rational engineering of resilient crops and the optimization of phytochemical production. Adopting a holistic view of plant metabolic networks is equally vital for addressing global challenges from climate adaptation to sustainable agriculture.
Protein homeostasis relies on chaperones such as HSP70 and HSP90, which assist in the folding, activation, and turnover of client proteins. Their activity is modulated by co-chaperones, many of which contain tetratricopeptide repeat (TPR) domains. A subset of these, known as carboxylate clamp TPR (CC-TPR) domains, possess distinctive structural features that mediate interactions with the chaperones' C-terminal EEVD motifs. This review focuses on plant TPR-containing co-chaperones, particularly those with CC-TPR domains, because they provide the structural basis for selective HSP70 and HSP90 recognition -a central but understudied aspect of plant proteostasis. We summarize advances in understanding the structure and diversity of plant TPR co-chaperones, and discuss three representative examples: AtRPAP3, a component of the R2T complex; HOP, a co-chaperone integrating hormonal and stress responses; and SGT1, a TPR protein that interacts with HSP90 through a TPR-independent mechanism and is crucial for immunity and development. Comparative evidence reveals both conservation and plant-specific diversification of TPR co-chaperone function, reflecting their adaptation to environmental and developmental cues. We conclude that plant TPR proteins constitute a versatile regulatory layer that coordinates chaperone activity across multiple cellular processes. Understanding their mechanisms will be essential to map the chaperone networks that underpin plant resilience and growth.
Legumes sanction root nodules containing rhizobial strains with low nitrogen fixation rates (less effectively fixing). Pea (Pisum sativum) nodules contain both undifferentiated bacteria and terminally differentiated nitrogen-fixing bacteroids. It is critical to understand how sanctions act on both bacteria and bacteroids, and how they differ. In addition, less effective strains could potentially evade sanctioning by entering the same nodule as an effective strain i.e., piggybacking. P. sativum was co-inoculated with pairwise combinations of three strains of rhizobia with different effectiveness, to test whether ineffective strains can evade sanctions in this way. We assessed the effect of sanctions on nodule populations of bacteria and bacteroids using flow cytometry and the effects on nodule internal structure using confocal microscopy. We show that sanctioning lowered bacteroid populations and caused a reduction in the size of bacteria. Sanctions also precipitated an early change in nodule cell morphology. In nodules containing two strains that differed in their nitrogen-fixation ability, both were treated equally. Thus, peas sanction whole nodules based on their nitrogen output, but do not sanction at the cellular level. Our results demonstrate peas conditionally sanction at the whole nodule level, providing stability to the symbiosis by reducing the fitness of ineffective strains, but cannot target individual strains in a mixed nodule.
The Fusarium metabolite culmorin (CUL) frequently co-occurs with the mycotoxin deoxynivalenol (DON) on cereals. While DON is recognized as a major Fusarium virulence factor on plants, the function of CUL is still unclear. Herein, we show that CUL-deficient F. graminearum mutants created by CLM1 deletion are less aggressive on wheat than the wild-type, accompanied by increased DON-3-glucoside/DON ratios in infected wheat ears. In root elongation assays with wheat and Brachypodium distachyon, CUL had no effect alone but significantly increased the toxicity of DON. Analysis of DON/CUL-treated roots further indicated that both wheat and B. distachyon are able to glucosylate CUL and that its presence impedes DON-glucosylation in both species. We identified two B. distachyon UDP-glucosyltransferases (UGT) able to glucosylate CUL and further investigated the effect of CUL on the kinetics of validated DON-glucosylating plant UGTs (BdUGT5g03300, HvUGT13248, OsUGT79). This suggested that CUL inhibits DON-glucosylation either by serving as competitive substrate with DON or by unproductive binding. Especially BdUGT5g03300 was strongly inhibited by CUL and even its glucosides. Our results indicate that CUL contributes to Fusarium virulence by weakening plant-defences related to UGT-catalysed DON-detoxification. As even CUL-glucosides are potentially inhibitory to UGTs, this implies a complex synergy of CUL with DON.
Efficient regeneration remains a major constraint for tomato (Solanum lycopersicum) transformation, particularly from leaf explants. Here, we evaluated chimeric GROWTH-REGULATING FACTOR (GRF)-GRF-INTERACTING FACTOR (GIF) proteins as regeneration enhancers and examined regulatory features underlying their activity. Fusion constructs based on Arabidopsis thaliana GRF5-GIF1 and their tomato homologs SlGRF4 and SlGIF1b markedly increased shoot regeneration from leaf explants, with similar enhancement observed in cotyledon-derived tissues, across three tomato cultivars. Regenerated shoots were able to form roots, indicating that GRF-GIF-mediated regeneration produced developmentally competent plantlets. Temporal expression profiling indicated that GRF-GIF transcript levels increased during regeneration and coincided with the induction of cytokinin- and auxin-associated regulators linked to meristem initiation. RNA-seq analyses revealed a shared early transcriptional program enriched for transcription factor activity and protein homeostasis, accompanied by broad repression of metabolism-related pathways. Despite strong phenotypic effects, GRF-GIF fusion proteins accumulated poorly in stable transformants. Transient expression assays suggested that their abundance is influenced by ubiquitin-proteasome system, and mutational analyses identified lysine residues affecting protein stability, although stabilization did not further enhance regeneration. Together, these findings support the use of GRF-GIF chimeras as effective enhancers of tomato regeneration from leaf explants and highlight the contribution of coordinated regulation at the transcript and protein levels to their functional window during cellular reprogramming.
Drought tolerance is a critical component contributing to the overall drought resistance of grasses. Still, our understanding of tolerance mechanisms in this group remains limited. We sought to investigate the mechanisms contributing to drought tolerance in zoysiagrasses, an economically important group of turfgrass cultivated worldwide. Experiments were performed using four cultivars with contrasting tolerances. Declines in the integrity of leaf cells and photochemistry preceded the initiation of leaf embolism in drought-susceptible, but not in drought-tolerant cultivars. Lobo, the most drought-tolerant cultivar, experienced cellular and photochemistry damage only after extensive embolism. Empire, the most drought-susceptible cultivar, experienced considerable damage to cells and the photosynthetic apparatus before, or soon after, the initiation of embolism. The occurrence of cell damage independently of xylem embolism in some of these grasses contrasts with the typical pattern observed in woody species. Leaves of all zoysiagrasses were equally highly resistant to embolism, with large estimated stomatal safety margins. Although embolism resistance did not explain differences in tolerance among these cultivars, we cannot rule out the importance of such highly resistant xylem to their overall drought tolerance. These results describe critical tolerance mechanisms in grasses and have important implications for breeding programs improving drought resistance of cultivated grasses.
p-Coumaroyl-CoA:monolignol transferase has been demonstrated to be involved in the coumaroylation of lignins in Brachypodium distachyon. However, the specific localization of acylation remains poorly documented at the tissue and cell wall levels in this species. Detecting molecules that are sometimes present at levels <1% in the cell wall remains a challenge, especially when suitable antibodies are not always available. In this work, we applied fluorescence microscopy methods, including large-beam excitation scanning at the SOLEIL synchrotron, to detect variations induced by hydroxycinnamic acids within B. distachyon stems. Using principal component analysis (PCA), fluorescence microscopy imaging effectively distinguished genotypes differing subtly in phenolic composition. The results were supported by immunolabeling, which confirmed that p-coumarate co-localizes with S-unit lignin in lignified tissues, while ferulate is broadly distributed. Strong autofluorescence in the mestome sheath and metaxylem pit area indicated a potential functional role for p-coumaric acid in these tissues. Finally, autofluorescence-based imaging and PCA proved to be a robust, non-destructive tool for visualizing lignin and phenolic compounds, offering valuable insights into cell wall specialization and phenolic function.
Increasing frequency of drought under climate change threatens crop production and intensifies pest pressures, yet the interactive effects of drought and herbivory on plant metabolism and ecological outcomes remain incompletely understood. We subjected sugar beet (Beta vulgaris) plants to moderate and high drought, alone or with infestation by the beet leaf miner (Pegomya cunicularia), and analyzed plant physiology, central metabolites, and volatile organic compound (VOC) emissions. Drought alone reduced growth and photosynthetic efficiency, while combined stress led to accentuated metabolic reprogramming, including increased amino acids and organic acids, and a concurrent suppression and alteration of VOC emissions, especially in plants affected by high drought and leaf mining. The resulting changes in VOC blends reduced plant attractiveness to ovipositing females, leading to fewer eggs laid on severely stressed plants. Contrastingly, moderate drought generated a nutrient-rich environment: larvae feeding on these plants exhibited the highest growth rates, larger pupae and adults, and increased feeding damage. High drought strongly limited both plant water content and larval development. These findings reveal a stress-dependent tradeoff between enhanced leaf nutritional quality and reduced host detectability, underscoring the importance of integrating multi-stress plant biology for future pest management and crop resilience.
The response of plants to local environmental stimuli can be activated in the tissues or organs that are directly challenged, as well as systemically in the remote and unstressed tissues or organs. Extracellular ATP (eATP) is known to play key roles in regulating many physiological processes in plants. Here, we demonstrated that local wounding at leaf or root of Arabidopsis thaliana seedling triggers a transient systemic increase in eATP levels, preceding the systemic elevation of [Ca2+]cyt levels in remote, un-wounded tissues. By using GCaMP3-p2k1 single-mutant, GCaMP3-p2k2 single-mutant, and GCaMP3-p2k1p2k2 double-mutant plants, it was found that local wounding-induced increases of [Ca2+]cyt levels at systemic tissues were weakened by P2Ks (eATP receptors) mutation. These results indicate that eATP/P2Ks are involved in regulating local and systemic enhancement of [Ca2+]cyt levels in response to local wounding.
Fruit maturity date is a key developmental trait in fruit trees, as it determines the timing at which fruits enter the ripening phase, thereby shaping harvest calendar and fruit quality. In peach, ripening time varies over several months, yet the genetic and regulatory basis underlying this extensive phenological diversity has remained largely unresolved. Here, we dissect the long-standing chromosome 4 maturity date locus (qMD4.1) and show that a multi-allelic series of structural variants in the upstream regulatory region of the transcription factor NAC1 explains most of the observed variation in ripening time in cultivated peach. Across multiple independent populations and diverse genetic backgrounds, these variants (collectively termed Md) stratify maturity date from ultra-early to late cultivars with largely additive and dosage-dependent effects. Using recombinant-based genetic dissection, long-read sequencing, transcriptomic analyses and epigenomic data integration, we show that Md alleles are consistently associated with allele-dependent shifts in the temporal dynamics of NAC1 transcript accumulation, and that the affected region overlaps with chromatin features characteristic of regulatory activity. By resolving the genetic architecture of a major phenological locus, our results support a central role for cis-regulatory structural variation in modulating developmental timing in peach and provide biologically interpretable markers for predicting maturity date. More broadly, this work illustrates how non-coding structural variation can contribute to variation in fruit developmental trajectories, with implications for breeding strategies aimed at modulating harvest windows in peach and other stone fruit species.
Two major classes of small nucleolar ribonucleoprotein (snoRNP) complexes have been identified in eukaryotic cells: C/D-box snoRNPs are responsible for 2'-O-methylation (2'-O-Me) of RNA, while H/ACA-box snoRNPs catalyse the conversion of uridine to pseudouridine (Ψ). In this review, we examine the current state of knowledge regarding C/D-box snoRNPs in plants. This knowledge is primarily derived from studies conducted on the model plant Arabidopsis thaliana. We provide a summary of reports concerning the organisation and expression of C/D-box snoRNAs, as well as the proteins that form the C/D-box snoRNP. In addition, we review the factors that are potentially involved in, or have been characterised as being involved in, the process of assembling and translocating C/D-box snoRNPs from the nucleoplasm to the nucleolus via Cajal bodies. Finally, the subject of 2'-O-methylation of ribosomal RNA (rRNA) in chloroplasts and mitochondria is presented, with a focus on the role of site-specific enzymes, as observed in bacterial systems, and in contrast to the involvement of nuclear C/D-box snoRNPs complexes.