Histone H3 lysine 27 trimethylation suppresses jasmonate biosynthesis and signaling to affect male fertility under high temperature in cotton

Histone modification H3K27me3 is essential during chilling-induced flowering in Litchi chinensis

Litchi (Litchi chinensis), a prominent fruit tree in the Sapindaceae, initiates flowering in response to low autumn and winter temperatures. This study investigates the epigenetic regulation of this process, focusing on the marks histone H3 lysine 27 trimethylation (H3K27me3) and its deposition genes during the chilling-induced floral induction (FId) and initiation stages. Our genomic analysis delineated the H3K27me3 deposition landscape across the prefloral induction (PFId), FId, and floral initiation (FIn) stages. We identified 5,635 differentially H3K27me3-modified genes (DHGs) in buds and 4,801 DHGs in leaves. Integration of the RNA-seq and ChIP-seq datasets identified 1,001 differentially regulated genes (DRGs) in buds and 675 DRGs in leaves, offering insights into the genes potentially targeted by H3K27me3. To probe the functional role of H3K27me3, we employed GSK343, a histone H3 lysine methyltransferase inhibitor. Treatment with GSK343 during the chilling-induced flowering process led to reduced H3K27me3 deposition at the TREHALOSE-6-PHOSPHATE SYNTHASE 1 (LcTPS1) and FRIGIDA (LcFRI) loci, resulting in increased gene expression. This manipulation delayed flowering and reduced flowering rates, confirming the pivotal role of H3K27me3 in chilling-induced flowering in litchi. Gene coexpression network analysis identified SHORT VEGETATIVE PHASE 10 (LcSVP10) as a crucial regulator in litchi flowering. Overexpression of LcSVP10 in Arabidopsis thaliana delayed flowering, indicating a conserved function in flowering time control. Our results elucidate the molecular and epigenetic mechanisms that govern FId in litchi and highlight the potential of epigenetic modifications to regulate flowering time in horticultural plants.

Constitutive expression of cucumber CsACS2 in Arabidopsis Thaliana disrupts anther dehiscence through ethylene signaling and DNA methylation pathways

KEY MESSAGE

Constitutive expression of cucumber CsACS2 in Arabidopsis disrupts anther dehiscence and male fertility via ethylene signaling and DNA methylation, revealing new avenues for enhancing crop reproductive traits. The cucumber gene CsACS2, encoding ACC (1-aminocyclopropane-1-carboxylic acid) synthase, plays a pivotal role in ethylene biosynthesis and sex determination. This study investigates the effects of constitutive CsACS2 expression in Arabidopsis thaliana on anther development and male fertility. Transgenic Arabidopsis plants overexpressing CsACS2 exhibited male sterility due to inhibited anther dehiscence, which was linked to suppressed secondary cell wall thickening. RNA-Seq analysis revealed upregulation of ethylene signaling pathway genes and downregulation of secondary cell wall biosynthesis genes, with gene set enrichment analysis indicating the involvement of DNA methylation. Rescue experiments demonstrated that silver nitrate (AgNO₃) effectively restored fertility, while 5-azacytidine (5-az) partially restored it, highlighting the roles of ethylene signaling and DNA methylation in this process. Constitutive CsACS2 expression in Arabidopsis disrupts anther development through ethylene signaling and DNA methylation pathways, providing new insights into the role of ethylene in plant reproductive development and potential applications in crop improvement.

H3K36 methyltransferase GhKMT3;1a and GhKMT3;2a promote flowering in upland cotton

BACKGROUND

The SET domain group (SDG) genes encode histone lysine methyltransferases, which regulate gene transcription by altering chromatin structure and play pivotal roles in plant flowering determination. However, few studies have investigated their role in the regulation of flowering in upland cotton.

RESULTS

A total of 86 SDG genes were identified through genome-wide analysis in upland cotton (Gossypium hirsutum). These genes were unevenly distributed across 25 chromosomes. Cluster analysis revealed that the 86 GhSDGs were divided into seven main branches. RNA-seq data and qRT‒PCR analysis revealed that lysine methyltransferase 3 (KMT3) genes were expressed at high levels in stamens, pistils and other floral organs. Using virus-induced gene silencing (VIGS), functional characterization of GhKMT3;1a and GhKMT3;2a revealed that, compared with those of the controls, the GhKMT3;1a- and GhKMT3;2a-silenced plants exhibited later budding and flowering and lower plant heightwere shorter. In addition, the expression of flowering-related genes (GhAP1, GhSOC1 and GhFT) significantly decreased and the expression level of GhSVP significantly increased in the GhKMT3;1a- and GhKMT3;2a-silenced plants compared with the control plants.

CONCLUSION

A total of 86 SDG genes were identified in upland cotton, among which GhKMT3;1a and GhKMT3;2a might regulate flowering by affecting the expression of GhAP1, GhSOC1, GhFT and GhSVP. These findings will provide genetic resources for advanced molecular breeding in the future.

Unraveling the genetic and molecular basis of heat stress in cotton

Human activities and climate change have resulted in frequent and intense weather fluctuations, leading to diverse abiotic stresses on crops which hampers greatly their metabolic activities. Heat stress, a prevalent abiotic factor, significantly influences cotton plant biological activities resulting in reducing yield and production. We must deepen our understanding of how plants respond to heat stress across various dimensions, encompassing genes, RNAs, proteins, metabolites for effective cotton breeding. Multi-omics methods, primarily genomics, transcriptomics, proteomics, metabolomics, and phenomics, proves instrumental in studying cotton's responses to abiotic stresses. Integrating genomics, transcriptomics, proteomics, and metabolomic is imperative for our better understanding regarding genetics and molecular basis of heat tolerance in cotton. The current review explores fundamental omics techniques, covering genomics, transcriptomics, proteomics, and metabolomics, to highlight the progress made in cotton omics research.

Genome-Wide Identification of Catalase Gene Family and the Function of SmCAT4 in Eggplant Response to Salt Stress

Salinity is an important abiotic stress, damaging plant tissues by causing a burst of reactive oxygen species (ROS). Catalase (CAT) enzyme coded by Catalase (CAT) genes are potent in reducing harmful ROS and hydrogen peroxide (H2O2) produced. Herein, we performed bioinformatics and functional characterization of four SmCAT genes, retrieved from the eggplant genome database. Evolutionary analysis CAT genes revealed that they are divided into subgroups I and II. The RT-qPCR analysis of SmCAT displayed a differential expression pattern in response to abiotic stresses. All the CAT proteins of eggplant were localized in the peroxisome, except for SmCAT4, which localized in the cytomembrane and nucleus. Silencing of SmCAT4 compromised the tolerance of eggplant to salt stress. Suppressed expression levels of salt stress defense related genes SmTAS14 and SmDHN1, as well as increase of H2O2 content and decrease of CAT enzyme activity was observed in the SmCAT4 silenced eggplants. Our data provided insightful knowledge of CAT gene family in eggplant. Positive regulation of eggplant response to salinity by SmCAT4 provides resource for future breeding programs.