The Plant Journal最新文献

Drought stress impairs plant growth and poses a serious threat to maize (Zea mays) production and yield. Nevertheless, the elucidation of the molecular basis of drought resistance in maize is still uncertain. In this study, we identified ZmSCE1a, a SUMO E2-conjugating enzyme, as a positive regulator of drought tolerance in maize. Molecular and biochemical assays indicated that E3 SUMO ligase ZmMMS21 acts together with ZmSCE1a to SUMOylate histone acetyltransferase complexes (ZmGCN5-ZmADA2b). SUMOylation of ZmGCN5 enhances its stability through the 26S proteasome pathway. Furthermore, ZmGCN5-overexpressing plants showed drought tolerance performance. It alleviated $O_2^{-}$ accumulation, malondialdehyde content, and ion permeability. What's more, the transcripts of stress-responsive genes and abscisic acid (ABA)-dependent genes were also significantly upregulated in ZmGCN5-overexpressing plants under drought stress. Overexpression of ZmGCN5 enhanced drought-induced ABA production in seedlings. Taken together, our results indicate that ZmSCE1a enhances the stability of ZmGCN5, thereby alleviating drought-induced oxidative damage and enhancing drought stress response in maize.

Flavonoids represent a diverse group of plant specialised metabolites which are also discussed in the context of dietary health and inflammatory response. Numerous studies have revealed that flavonoids play a central role in plant acclimation to abiotic factors like low temperature or high light, but their structural and functional diversity frequently prevents a detailed mechanistic understanding. Further complexity in analysing flavonoid metabolism arises from the different subcellular compartments which are involved in biosynthesis and storage. In the present study, non-aqueous fractionation of Arabidopsis leaf tissue was combined with metabolomics and proteomics analysis to reveal the effects of flavonoid deficiencies on subcellular metabolism during cold acclimation. During the first 3 days of a 2-week cold acclimation period, flavonoid deficiency was observed to affect pyruvate, citrate and glutamate metabolism which indicated a role in stabilising C/N metabolism and photosynthesis. Also, tetrahydrofolate metabolism was found to be affected, which had significant effects on the proteome of the photorespiratory pathway. In the late stage of cold acclimation, flavonoid deficiency was found to affect protein stability, folding and proteasomal degradation, which resulted in a significant decrease in total protein amounts in both mutants. In summary, these findings suggest that flavonoid metabolism plays different roles in the early and late stages of plant cold acclimation and significantly contributes to establishing a new protein homeostasis in a changing environment.

The BonnMu resource is a transposon tagged mutant collection designed for functional genomics studies in maize. To expand this resource, we crossed an active Mutator (Mu) stock with dent (B73, Co125) and flint (DK105, EP1, and F7) germplasm, resulting in the generation of 8064 mutagenized BonnMu F₂-families. Sequencing of these Mu-tagged families revealed 425 924 presumptive heritable Mu insertions affecting 36 612 (83%) of the 44 303 high-confidence gene models of maize (B73v5). On average, we observed 12 Mu insertions per gene (425 924 total insertions/36 612 affected genes) and 53 insertions per BonnMu F₂-family (425 924 total insertions/8064 families). Mu insertions and photos of seedling phenotypes from segregating BonnMu F₂-families can be accessed through the Maize Genetics and Genomics Database (MaizeGDB). Downstream examination via the automated Mutant-seq Workflow Utility (MuWU) identified 94% of the presumptive germinal insertion sites in genic regions and only a small fraction of 6% inserting in non-coding intergenic sequences of the genome. Consistently, Mu insertions aligned with gene-dense chromosomal arms. In total, 42% of all BonnMu insertions were located in the 5' untranslated region of genes, corresponding to accessible chromatin. Furthermore, for 38% of the insertions (163 843 of 425 924 total insertions) Mu1, Mu8 and MuDR were confirmed to be the causal Mu elements. Our publicly accessible European BonnMu resource has archived insertions covering two major germplasm groups, thus facilitating both forward and reverse genetics studies.

Licorice is one of the most extensively studied medicinal plants in the world, whose roots and rhizomes have long been used as both a sweetener and an essential component in numerous herbal preparations. However, the genus Glycyrrhiza has a complex composition, and the interspecies chromosomal relationships, origin, and evolution are still largely unclear. Here, we develop a set of whole-chromosome painting probes that allowed identification of all eight chromosomes of licorice on same metaphase chromosomes. Comparative chromosome painting analyses in seven different Glycyrrhiza species revealed that the genus Glycyrrhiza maintained extraordinarily conserved chromosomal synteny after about 3-12 million years of divergence. No cytologically visible inter-chromosomal rearrangements were identified in any species. By comparative chromosomal karyotype analyses, we revealed interspecific chromosome evolutionary relationships and dramatic variable chromosomal karyotype after independent divergence and demonstrated that G. prostrate was the most closely related to the ancestral type among the seven Glycyrrhiza species. Furthermore, we also discovered a G. glandulosa seed with distinct triploid-genome for the first time in China, suggesting the existence of a polyploid evolutionary pathway in the genus Glycyrrhiza, which challenges the previous notion that only diploids of licorice existed in nature. This study expands our knowledge of the chromosome evolution of licorice and will lay an important foundation for the genome origin and evolution studies in the genus Glycyrrhiza.

The sophisticated regulation of state transition is required to maintain optimal photosynthetic performance under fluctuating light condition, through balancing the absorbed light energy between photosystem II and photosystem I. This exquisite process incorporates phosphorylation and dephosphorylation of light-harvesting complexes and PSII core subunits, accomplished by thylakoid membrane-localized kinases and phosphatases that have not been fully identified. In this study, one Chlamydomonas high light response gene, THYLAKOID ENRICHED FRACTION 8 (TEF8), was characterized. The Chlamydomonas tef8 mutant showed high light sensitivity and defective state transition. The enzymatic activity assays showed that TEF8 is a bona fide phosphatase localized in thylakoid membranes. Biochemical assays, including BN-PAGE, pull-down, and phosphopeptide mass spectrometry, proved that TEF8 associates with photosystem II and is involved in the dephosphorylation of D2 and CP29 subunits during state 2 to state 1 transition. Taken together, our results identified TEF8 as a thylakoid phosphatase with multiple dephosphorylation targets on photosystem II, and provide new insight into the regulatory mechanism of state transition and high light resistance in Chlamydomonas.

Boron (B) is an important limiting factor for plant growth and yield in saline soils, but the underlying molecular mechanisms remain poorly understood. In this study, we found that appropriate B supply obviously complemented rapeseed (Brassica napus L.) growth under salinity accompanied by higher biomass production and less reactive oxygen species accumulation. Determination of Na⁺ content in shoots and roots indicated that B significantly repressed root-to-shoot Na⁺ translocation, and non-invasive micro-tests of root xylem sap demonstrated that B increased xylem Na⁺ unloading in the roots of rapeseed plants under salinity. Comparative transcriptomic profiling revealed that B strongly upregulated BnaHKT1s expression, especially BnaA2.HKT1, in rapeseed roots exposed to salinity. In situ hybridizations analysis showed that BnaA2.HKT1 was significantly induced in root stelar tissues by high B (HB) under salinity. Green fluorescent protein and yeast heterologous expression showed that BnaA2.HKT1 functioned as a plasma membrane-localized Na⁺ transporter. Knockout of BnaA2.HKT1 by CRISPR/Cas9 resulted in hypersensitive of rapeseed plants to salinity even under HB condition, with higher shoot Na⁺ accumulation and lower biomass production. By contrast, overexpression of BnaA2.HKT1 ameliorated salinity-induced growth inhibition under B deficiency and salinity. Overall, our results proposed that B functioned as a positive regulator for the rapeseed growth and seed production under salt stress through facilitating BnaA2.HKT1-mediated root xylem Na⁺ unloading. This study may also provide an alternative strategy for the improvement of crop growth and development in saline soils.

Stylosanthes is an important forage legume in tropical areas with strong resistance to aluminum (Al) toxicity, though knowledge of mechanisms underlying this resistance remains fragmentary. We found that border-like cells (BLCs) were constitutively produced surrounding the root tips of all 54 examined Stylosanthes guianensis genotypes, but not the Stylosanthes viscose genotype TF0140. In genotypic comparisons under Al conditions, the S. guianensis genotype RY#2 retained significantly more Al in BLCs and thereby showed higher relative root growth than TF0140. Formation of BLCs accompanied changes in cell wall pectin epitopes and differential expression of genes involved in pectin metabolism, including a polygalacturonase (SgPG1). The expression pattern of SgPG1 was consistent with the formation of BLCs in both RY#2 and TF0140. SgPG1 was localized in cell walls and exhibited high activities mediating demethyl-esterified homogalacturonan degradation. Overexpressing SgPG1 changed cell wall pectin epitopes, enhanced BLCs production, and Al resistance in both Arabidopsis and Stylosanthes hairy roots. Furthermore, combining protein-DNA binding assays in vitro and in vivo, a bHLH transcription factor SgbHLH19 was demonstrated to be the upstream regulator of SgPG1. Our study demonstrates that S. guianensis Al resistance mainly relies on BLCs, whose formation involves cell wall pectin epitope modification by SgPG1.

The use of deep learning techniques to identify grape leaf diseases relies on large, high-quality datasets. However, a large number of images occupy more computing resources and are prone to pattern collapse during training. In this paper, a depth-separable multifeature generative adversarial network (DMFGAN) was proposed to enhance grape leaf disease data. First, a multifeature extraction block (MFEB) based on the four-channel feature fusion strategy is designed to improve the quality of the generated image and avoid the problem of poor feature learning ability of the adversarial generation network caused by the single-channel feature extraction method. Second, a depth-based D-discriminator is designed to improve the discriminator capability and reduce the number of model parameters. Third, SeLU activation function was substituted for DCGAN activation function to overcome the problem that DCGAN activation function was not enough to fit grape leaf disease image data. Finally, an MFLoss function with a gradient penalty term is proposed to reduce the mode collapse during the training of generative adversarial networks. By comparing the visual indicators and evaluation indicators of the images generated by different models, and using the recognition network to verify the enhanced grape disease data, the results show that the method is effective in enhancing grape leaf disease data. Under the same experimental conditions, DMFGAN generates higher quality and more diverse images with fewer parameters than other generative adversarial networks. The mode breakdown times of generative adversarial networks in training process are reduced, which is more effective in practical application.

Plants depend heavily on soil nutrients for growth, development and defence. Nutrient availability is crucial not only for sustaining vital biochemical processes but also for mounting effective defences against a diverse array of pathogens. Macronutrients such as nitrogen, phosphorus and potassium significantly influence plant defence mechanisms by providing essential building blocks for the synthesis of defence compounds, immune signalling and physiological responses like stomatal regulation. Micronutrients like zinc, copper and iron are essential for balancing reactive oxygen species and other reactive compounds in plant immune responses. Although substantial circumstantial evidence links nutrient availability to plant defence, the molecular mechanisms underlying this process have only recently started to be understood. This review focuses on summarizing recent advances in understanding the molecular mechanisms by which nitrogen, phosphorus and iron interact with plant defence mechanisms and explores the potential for engineering nutritional immunity in crops to enhance their resilience against pathogens.

Lignification of the cell wall in pear (Pyrus) fruit results in the formation of stone cells, which affects the texture and quality of the fruit. However, it is still unclear that how different transcription factors (TFs) work together to coordinate the synthesis and deposition of lignin. Here, we examined the transcriptome of pear varieties with different stone cell contents and found a key TF (PbAGL7) that can promote the increase of stone cell contents and secondary cell wall thicknesses. In addition, PbAGL7 can facilitate the expression level of lignin biosynthesis-related genes and accelerate the lignin biosynthesis in pear fruit and Arabidopsis. However, PbAGL7 did not directly bind to the promoters of PbC3H1 and PbHCT17 which are crucial genes involved in lignin biosynthesis. On the other hand, yeast two-hybrid (Y2H) library showed that PbNAC47 and PbMYB73 interacted with PbAGL7 in the nucleus. PbNAC47 and PbMYB73 also increased the stone cell and lignin contents, and upregulated the expressions of PbC3H1 and PbHCT17 by binding to the SNBE and AC elements, respectively. Moreover, PbNAC47 also interacted with PbMYB73 to form PbAGL7-PbNAC47-PbMYB73 complex. This complex significantly activated the expression levels of PbC3H1 and PbHCT17 and promoted lignin biosynthesis to form stone cells in pear fruit. Overall, our study provides new insights into the molecular mechanism of TFs that coordinately regulate the stone cell formation in pear fruit and extend our knowledge to understand cell wall lignification in plants.