Plant, Cell & Environment最新文献

The segmentation hypothesis, a framework for understanding plant drought adaptive strategy, has long been based on hydraulic resistance and vulnerability. Storage of water and carbohydrate resources is another critical function and shapes plant drought adaption and fitness together with hydraulic efficiency and vulnerability. However, patterns and implications of the interdependency of stored water and carbohydrate resources in the context of the segmentation hypothesis are poorly understood. We measured resource pools (relative water content [RWC] soluble sugar [SS] and starch [S]) and anatomical features of leaves and supporting twigs for 36 trees in a subtropical population during the dry season when the Budyko's aridity index was 0.362. For each tree, we rank-transformed the RWC (RWC_rank), SS (SS_rank), and S (S_rank) and characterised the resource segmentation within organs using Ln(RWC_rank/SS_rank) and Ln(RWC_rank/S_rank). We also assessed the resource segmentation between organs using the difference in resource pools between leaves and twigs (RWC_leaf-twig, SS_leaf-twig, and S_leaf-twig). Resource segmentation was much more effective than the organ-level resource pool alone in predicting intraspecific variation of tree growth rates. Fast-growing individuals were mainly characterised by lower leaf Ln(RWC_rank/SS_rank), higher twig Ln(RWC_rank/SS_rank), and lower SS_leaf-twig. The resource segmentation strategy of fast-growing individuals was associated with anatomical attributes that facilitate phloem SS loading and unloading and thus water supply upstream. Our results highlight that resource segmentation is an important dimension of plant drought adaptive strategies and enables better prediction of tree growth vigour than resource pool attributes individually.

The increasing frequency of concurrent heat and drought stress poses a significant challenge to agricultural productivity, particularly for cool-season grain legumes, including broad bean (Vicia Faba L.), lupin (Lupinus spp.), lentil (Lens culinaris Medik), chickpea (Cicer arietinum L.), grasspea (Lathyrus sativus L.), pea (Pisum sativum L.), and common vetch (Vicia sativa L.). These legumes play a vital role in sustainable agricultural systems due to their nitrogen-fixing ability and high nutritional value. This review synthesizes current knowledge of the impacts and tolerance mechanisms associated with combined heat and drought stresses in these crops. We evaluate physiological and biochemical responses to combined heat and drought stress, focusing on their detrimental effects on growth, development, and yield. Key genetic and molecular mechanisms, such as the roles of osmolytes, antioxidants, and stress-responsive genes, are explored. We also discuss the intricate interplay between heat and drought stress signaling pathways, including the involvement of Ca²⁺ ions, reactive oxygen species, transcription factor DREB2A, and the endoplasmic reticulum in mediating stress responses. This comprehensive analysis offers new insights into developing resilient legume varieties to enhance agricultural sustainability under climate change. Future research should prioritize integrating omics technologies to unravel plant responses to combined abiotic stresses.

Plant-specific homeodomain-leucine zipper I (HD-Zip I) transcription factors (TFs) crucially regulate plant drought tolerance. However, their specific roles in maize (Zea mays L.) regulating drought tolerance remain largely unreported. Here, we screened a maize HD-Zip I TF family gene, ZmHB53, and clarified its role in drought stress. ZmHB53 overexpression maize plants exhibited sensitivity to abscisic acid (ABA), tolerant to polyethylene glycol (PEG 6000)-induced stress during germination, along with improved seedling drought resistance. Compared to the wild-type, ZmHB53 overexpression lines show higher water retention, biomass, and survival rates, and reduced water loss and stomatal size under drought, suggesting ZmHB53's role in drought adaptation. DNA affinity purification sequencing (DAP-Seq), yeast one hybrid, electrophoretic mobility shift assay (EMSA), and dual luciferase showed that ZmHB53 directly bound to and upregulated the expression of ABA receptor ZmPYL4. Meanwhile, transgenic plants overexpressing ZmPYL4 also exhibit ABA sensitivity and drought tolerance. The research results provide novel insights into the regulatory role of ZmHB53 and ZmPYL4 in enhancing maize's drought tolerance, establishing a foundation for future validation and potential application of ZmHB53 in strategies to improve maize resistance to drought.

Grain size and weight of main-crop are larger than those of ratoon rice, indicating that increasing grain size and weight of ratoon rice is an effective way to increase rice yield. Thus, grain length (GL), grain width (GW), and thousand-grain weight (TGW) of main-crop and ratoon rice in 159 indica rice accessions were used to associate with 2 017 495 SNP markers to detect quantitative trait nucleotides (QTNs) and their interactions with meteorological factors (QMIs), such as temperature and sunlight hours. Around 59 QMIs identified for temperature and 80 QMIs identified for sunlight hours, first, candidate gene LOC_Os02g40840 for GW and LOC_Os04g45480 for TGW were found to interact with temperature, while LOC_Os01g19970 for GL, LOC_Os02g39360 and LOC_Os07g05720 for GW, and LOC_Os07g49460 for TGW were found to interact with sunlight hours. Based on the results of previous studies, LOC_Os04g45480 exhibits high expression levels in the main-crop under higher temperature, thereby enhancing the accumulation of the auxin receptor TIR1. TIR1, in turn, promotes starch accumulation in the endosperm, explaining why TGW is heavier in main-crop than in ratoon rice. Finally, the analysis of best linear unbiased prediction values revealed 1 (LOC_Os08g10350) and 3 (LOC_Os02g50860, LOC_Os08g28680, and LOC_Os08g29160) candidate genes responsible for GW and TGW, respectively. In addition, we discussed the four available and six unavailable candidate genes in ratoon rice breeding. This study provides new method and genes for studying differences in grain size-related traits between main-crop and ratoon rice.

Flower color is a crucial trait that attracts pollinators and determines the ornamental value of floral crops. Cymbidium lowianum, one of the most important breeding parent of Cymbidium hybrids, has two flower morphs (normal and albino) that differ in flower lip color. However, the molecular mechanisms underlying flower color formation in C. lowianum are not well understood. In this study, comparative metabolomic analysis between normal and albino flower lip tissues indicated that cyanidin-3-O-glucoside content was significantly higher in red epichiles than in other lip tissues. This finding suggests that cyanidin-3-O-glucoside is responsible for color variation and differentiation in the lip in C. lowianum. We also found that red coloration in C. lowianum flower is correlated with high levels of F3'H expression; further, anthocyanins, carotenoids and chlorophyll coordinate to influence sepal and petal coloration during flower development. In transgenic Arabidopsis lines, overexpression of F3'H increased anthocyanin concentration, overexpression of BCH increased carotenoid concentration, whereas overexpression of HEMG and CHLI both increased chlorophyll concentration. Identification and assessment of several transcription factors revealed that MYB308-1 activates BCH, MYB111 and PIF4-2 activate HEMG and CHLI expression during flower development. Importantly, MYB14-1 shows interaction with PIF4-2, and appears to act as a connector between anthocyanin and chlorophyll biosynthesis by either activating F3'H expression or inhibiting CHLI expression. These results indicate that, in C. lowianum, variation in flower color and differentiation of lip color patterns are primarily regulated by the types and concentrations of flavonoids; further, carotenoids and chlorophyll also influence flower coloration during development.

Pokkah boeng disease (PBD), a common and highly destructive disease of sugarcane, is mainly caused by Fusarium sacchari. Breeding sugarcane resistant to PBD is challenging due to the limited availability of immune or highly resistant germplasm resources. Host-induced gene silencing (HIGS) based on RNA interference (RNAi) is a promising disease-control method that offers strong disease-targeting ability with low environmental impact. This study found that silencing either three FsCYP51 genes (FsCYP51A, FsCYP51B and FsCYP51C) simultaneous or two of them (FsCYP51A and FsCYP51C) could inhibit the growth, development, and virulence of F. sacchari. Subsequently, we developed CYP51-HIGS transgenic sugarcane lines using gene-gun genetic transformation and obtained seven lines expressing dsFsCYP51. Both the results of laboratory inoculation assays and field trials indicated that all the seven transgenic lines had significant resistance to PBD. Moreover, in the field trials, the yield losses of transgenic sugarcane due to PBD were reduced compared with those of the control. This is the first report using the HIGS strategy to inhibit PBD infection in sugarcane. This breakthrough provides clear guidelines and practical approaches for the future breeding of sugarcane varieties with strong antifungal resistance.

Tonoplast intrinsic proteins (TIPs) are the channel-forming proteins predominantly found in the tonoplast of plant cells. Despite the identification of TIPs in numerous plant species, very less is known about the precise role of different TIP subgroups. In the present study, two genes belonging to the TIP3 subgroup were studied to understand tissue-specific role and solute transport activity. The soybean GmTIP3-1 and GmTIP3-2 were found to be expressed exclusively in seeds. Unlike rest of the aquaporins (AQPs), the expression of GmTIP3s gradually increased during seed maturation. The GmTIP3s also show higher expression during the initiation of seed germination, suggesting their potential role in the solute transport during seed maturation and germination. Further, GmTIP3-1 and GmTIP3-2 were functionally characterised to understand the structure, pore morphology, pore hydrophobicity, sub-cellular localization, and solute specificity. The solute specificity of TIPs is crucial in various physiological and developmental processes. Solute transport activity studied using yeast growth and survivability assay suggests that GmTIP3-1 and GmTIP3-2 can transport hydrogen peroxide (H₂O₂) and boric acid, both of which are known to play significant role in seed germination. The information provided here will help to understand the precise role of TIP3 genes in seed development and germination.

Floral organ development, pollen germination and pollen tube growth are crucial for plant sexual reproduction. Phytohormones maintain these processes by regulating the expression and activity of various transcription factors. ICE1, a MYC-like bHLH transcription factor, has been revealed to be involved in cold acclimatisation of Arabidopsis. This study shows that ICE1 regulates multiple aspects of sexual reproduction, including stamen development, pollen development and germination. Loss-of-function mutants of ICE1 exhibit floral organs with shorter filaments, defective anther dehiscence and lower pollen viability compared to the wild type. These abnormalities result in disrupted fertilisation, leading to short siliques, a high rate of seed abortion, and dark, shriveled mature seeds. JAZ proteins (JAZ1 and JAZ9) interact with ICE1, inhibiting its transcriptional activity on jasmonic acid (JA)-responsive genes, including MYB21, MYB24 and MYB108. This study highlights the essential role of ICE1 as a signalling agent in the JA-regulated maintenance of sexual reproduction in Arabidopsis thaliana.

Hairy-root transformation is widely used to generate transgenic plant roots for genetic functional characterisation studies. However, transformation efficiency can be limited, largely due to the use of binary vectors. Here, we report on the development of novel integrative vectors that significantly increase the transformation efficiency of hairy roots. This includes pHGUS7, for promoter::reporter visualisation studies, and pHOG13, for genetic insertion and overexpression studies. These vectors have been designed to simplify cloning workflows, enhance the selection of positively transformed Agrobacterium colonies, and increase the transformation efficiency and ease of selection of genetically modified hairy roots. To demonstrate the efficacy of the new vectors, Too Much Love (TML) encoding genes acting in the Autoregulation Of Nodulation (AON) pathway of soybeans were investigated. Both constructs provided significantly higher transformation rates than the binary vector control, often resulting in > 70% of the roots being transformed. This was achieved using either whole-plant seedlings or cotyledonary nodes in tissue culture. Overexpression of each individual TML encoding gene (GmTML1a, GmTML1b and GmTML2) using pHOG13 resulted in a significant reduction in nodule number, demonstrating the role of all three in inhibiting nodule organogenesis. Moreover, reporter-fusions with the promoter of each TML encoding gene using pHGUS7 revealed that each exhibits a unique pattern of expression in nodules, with GmTML1b displaying considerably stronger expression than GmTML1a or GmTML2. Taken together, these results demonstrate the utility and efficiency of the new pHOG13 and pHGUS7 integrative vectors in hairy-root transformation, and improve our understanding of the critical TML-encoding genes in soybean nodulation control.

Common ash (Fraxinus excelsior) is under intensive attack from the invasive alien pathogenic fungus Hymenoscyphus fraxineus, causing ash dieback at epidemic levels throughout Europe. Previous studies have found significant genetic variation among genotypes in ash dieback susceptibility and that host phenology, such as autumn yellowing, is correlated with susceptibility of ash trees to H. fraxineus; however, the genomic basis of ash dieback tolerance in F. excelsior requires further investigation. Here, we integrate quantitative genetics based on multiple replicates and genome-wide association analyses with machine learning to reveal the genetic architecture of ash dieback tolerance and of phenological traits in F. excelsior populations in six European countries (Austria, Denmark, Germany, Ireland, Lithuania, Sweden). Based on phenotypic data of 486 F. excelsior replicated genotypes we observed negative genotypic correlations between crown damage caused by ash dieback and intensity of autumn leaf yellowing within multiple sampling sites. Our results suggest that the examined traits are polygenic and using genomic prediction models, with ranked single nucleotide polymorphisms (SNPs) based on GWAS associations as input, a large proportion of the variation was predicted by unlinked SNPs. Based on 100 unlinked SNPs, we can predict 55% of the variation in disease tolerance among genotypes (as phenotyped in genetic trials), increasing to a maximum of 63% when predicted from 9155 SNPs. In autumn leaf yellowing, 52% of variation is predicted by 100 unlinked SNPs, reaching a peak of 72% using 3740 SNPs. Based on feature permutations within genomic prediction models, a total of eight nonsynonymous SNPs linked to ash dieback crown damage and autumn leaf yellowing (three and five SNPs, respectively) were identified, these were located within genes related to plant defence (pattern triggered immunity, pathogen detection) and phenology (regulation of flowering and seed maturation, auxin transport). We did not find an overlap between genes associated with crown damage level and autumn leaf yellowing. Hence, our results shed light on the difference in the genomic basis of ADB tolerance and autumn leaf yellowing despite these two traits being correlated in quantitative genetic analysis. Overall, our methods show the applicability of genomic prediction models when combined with GWAS to reveal the genomic architecture of polygenic disease tolerance enabling the identification of ash dieback tolerant trees for breeding or conservation purposes.