Plant Molecular Biology最新文献

The regulation of flowering is crucial for optimizing palm oil yield and ensuring adaptation to environmental conditions. This study investigates two FLOWERING LOCUS T (FT) homologs in oil palm (Elaeis guineensis), EgHd3a-1 and EgHd3a-2, to elucidate their roles in flowering induction and developmental processes. Quantitative PCR and GUS reporter assays in Arabidopsis thaliana revealed that EgHd3a-1 is predominantly expressed in reproductive tissues and vascular structures, functioning analogously to FT as a floral inducer. In contrast, EgHd3a-2 displayed broader expressions across both vegetative and reproductive tissues, particularly during early growth stages, suggesting a role in organ development rather than direct floral induction. Overexpression of EgHd3a-1 and EgHd3a-2 in A. thaliana resulted in distinct flowering phenotypes, with EgHd3a-1 mutants exhibiting accelerated flowering under long-day conditions. Promoter analysis of pEgHd3a-1 and pEgHd3a-2 identified unique cis-acting regulatory elements associated with tissue specificity and environmental responsiveness, reinforcing their complementary functions. These findings provide a molecular basis for targeted genetic modification of flowering time in oil palm, offering significant potential for accelerating breeding cycles, improving yields optimization, and enhancing resilience to environmental changes.

While the role of succinic semialdehyde (SSA) dehydrogenase (SSADH; also known as gabD) is well-reported from model plants, the lack of functionality and structure of SSADH from citrus represents a significant knowledge gap. Herein, genome-wide analyses identified 17 high-confidence SSADH-like proteins from Citrus sinensis, among which three putative SSADHs have potential GABA dehydrogenase function. Sequence alignment, phylogenetic analyses, and domain architecture demonstrated high conservation among CsSSADHs (aka CsgabD) and their homologs across diverse plant taxa. Notably, CsSSADH-2 lacked a conserved QGIVC motif found in CsSSADH-1/-3. Secondary structure analyses indicated conserved aldehyde dehydrogenase domains. Homology-based 3D modeling predicted CsSSADH-1 and 2 as homo-tetramers; however, AlphaFold2-based modeling suggested their full-length monomer structures. PPI networks revealed CsSSADH-1 interacts with 10 proteins, primarily involved in GABA/succinate metabolism and the TCA cycle. Docking studies indicated that CsSSADH-1 displayed acceptable affinity and binding modes with GABA, SSA, and succinate. GABA supplementation enhances CsSSADH expression, GABA, and succinate content in a dose-dependent manner in both healthy and infected citrus plants under greenhouse conditions. CsSSADH was involved in citrus responses to 'Candidatus Liberibacter asiaticus' and/or its vector, Diaphorina citri. Nevertheless, GABA accumulation under biotic stress leads to condition-specific rerouting of GABA metabolism. Chemical inhibition of CsSSADH resulted in increased GABA accumulation but reduced succinate levels in both healthy and infected plants. This study offers the first comprehensive characterization of C. sinensis SSADH isoforms, providing insights into their evolutionary divergence, structural features, and potential functions, and enhancing our understanding of their possible roles in GABA metabolism and citrus defense responses.

Caffeoyl-CoA O-methyltransferase (CCoAOMT) is a key enzyme in the phenylpropanoid pathway that plays a crucial role in lignin biosynthesis; however, its functional role in Medicago sativa remains poorly understood. In this study, we identified 44 MsCCoAOMT family members and analyzed their expression profiles across eight tissues and under polyethylene glycol (PEG)-induced osmotic stress. Among them, MsCCoAOMTh3 displayed preferential expression in roots and flowers, and was significantly upregulated in roots and stems following PEG treatment, suggesting a potential role in both plant development and stress responses. Functional validation through heterologous expression in Arabidopsis thaliana revealed that MsCCoAOMTh3 overexpression markedly increased lignin accumulation and promoted xylem development in roots. Furthermore, transgenic lines displayed enhanced drought tolerance, characterized by elevated antioxidant enzyme activity and reduced malondialdehyde (MDA) levels. Collectively, these findings suggest that MsCCoAOMTh3 acts as a positive regulator of root lignification and enhances drought tolerance by modulating both stress-responsive and lignin biosynthesis-related genes.

Auxin is one of the major driving forces of plant development and requires careful regulation of transporter proteins to establish polar auxin transport. The PIN-FORMED (PIN) family plays a pivotal role in plant development by establishing auxin gradients that govern vascular patterning and organogenesis. However, the PIN family remains severely underexplored in Setaria viridis, a well-established model for C₄ monocots. In this study, we identified and characterized 13 PIN genes in the S. viridis genome. Phylogenetic and collinearity analyses revealed duplication events in the SvPIN1, SvPIN5 and SvPIN10 subfamilies. Structural analysis uncovered unique features, including potential pseudogenization of SvPIN5a. Expression profiling across five developmental stages unveiled the potential developmental roles of SvPINs, with SvPIN1 and SvPIN10 paralogues predominantly expressed in shoots and panicles, SvPIN2 and SvPIN9 in roots, while SvPIN5b showed leaf-enriched expression, suggesting potential involvement in leaf vascular development. Hormonal treatments in callus cultures revealed auxin-mediated upregulation of SvPIN1b, SvPIN2, SvPIN5d, SvPIN8 and SvPIN10a. Our findings provide significant insights into the role of PIN genes in S. viridis and other C₄ monocots, establishing a foundation for future functional studies and offering potential targets for crop improvement through auxin transport manipulation.

Thermal energy has become an increasingly severe environmental stressor to cash crop production worldwide because of global warming. Annexins, proteinaceous protectants against abiotic stress, are multifunctional proteins capable of peroxidase- and Ca²⁺-dependent and Ca²⁺-independent binding to or insertion into membranes. Annexins in plants belong to the annexin D family and are further clustered into six phylogenetic clades on the basis of their structural diversity. A previous study in peanut identified six annexins, but their thermotolerance functions remain unknown. In this study, we report that AhANN6, a peanut annexin, confers heat resistance in Escherichia coli and Arabidopsis when overexpressed. AhANN6 expression led to positive responses to drought stress, ABA supplementation, and heat stress in leaves and was developmentally regulated during germination and pegging. The AhANN6-YFP fusion protein was targeted to the plasma membrane of tobacco cells, suggesting that AhANN6 is localized in the cell membrane. AhANN6-overexpressing E. coli exhibited better growth under heat stress and oxidative stress, validating the molecular function of AhANN6 against abiotic stress. AhANN6-overexpressing Arabidopsis also presented increased heat resistance during vegetative growth. The decreased response of electrolyte leakage in the transgenic Arabidopsis to heat stress indicates potentially improved membrane stability as a result of AhANN6 overexpression. Additionally, the overexpression of AhANN6 in Arabidopsis led to increased expression of AtPOD and AtAPX, key enzyme-encoding genes involved in ROS scavenging, suggesting that AhANN6 is involved in maintaining ROS detoxification. Our findings suggest that AhANN6 plays a crucial role in protecting cell membrane integrity and promoting vegetative growth under adverse environmental stressors.