Glycogen synthase kinase 3 (GSK3) kinases are evolutionarily conserved regulators of plant development and stress signaling, yet their contributions to thermotolerance in cool-adapted Brassica crops remain poorly understood. Here, we identified 16 BrSK genes in the Caixin (Brassica rapa ssp. chinensis var. parachinensis) genome, all harboring intact catalytic motifs indicative of functional kinase activity. Spatiotemporal expression profiling revealed preferential accumulation of BrSK transcripts in stem apices and floral organs during reproductive transition, while promoter analysis identified abundant heat- and abiotic stress-responsive cis-elements. Under heat stress, BrSK21, BrSK22, and BrSK23 displayed striking genotype-specific expression dynamics. BrSK21/22/23 transcripts were stably suppressed in the heat-tolerant cultivar '49-19' but transiently declined before rapidly rebounding in the heat-sensitive 'Liuye 50', mirroring RNA-seq profiles. Protein-protein interaction assays (Y2H, BiFC, and LCI) demonstrated specific associations between BrSK kinases and BrHSFA1. Functional validation via VIGS revealed that silencing of BrSK21 significantly enhanced thermotolerance, with triple silencing of BrSK21/22/23 conferring additive protection, indicating functional redundancy within the BrSK2 subfamily. Collectively, these findings establish the BrSK2 subfamily as negative regulators of heat tolerance in Caixin, likely via modulation of BrHSFA1 expression. This work identifies high-priority targets for molecular breeding of climate-resilient Brassica vegetables.
Haobo Yang, Kehang Chen, Rahat Sharif et al.· Plant Science· 0 citations
Glyphodes pyloalis Walker is a devastating phytophagous pest of mulberry (Morus spp.) that severely compromises leaf yield and quality, thereby threatening sericultural productivity. Although jasmonic acid (JA) and salicylic acid (SA) are well-established regulators of plant antiherbivore defenses, their specific roles in modulating mulberry responses to G. pyloalis herbivory remain poorly understood. Here, we employed an integrative approach combining herbivory bioassays, exogenous hormone treatment, physiological analysis, and RNA-sequencing (RNA-seq) to dissect JA- and SA-mediated defense networks in mulberry. Exogenous application of both hormones enhanced chlorophyll content, with JA exerting the strongest effect. However, they differentially modulated antioxidant enzyme activities, with SA primarily elevating superoxide dismutase (SOD) and JA enhancing peroxidase (POD) and catalase (CAT). Transcriptomic and functional-enrichment analyses showed that JA-responsive DEGs were predominantly associated with photoprotection, carbohydrate metabolism, phenylpropanoid and flavonoid biosynthesis, MAPK signaling, ABC transporters, and defense-related enzyme functions. By comparison, SA-responsive DEGs were strongly associated with photosynthesis-related gene expression, chloroplast organization, carbon metabolism, glutathione metabolism, and systemic immune-related processes. Notably, several key transcription factors, including MaHDZIP1, MaLBD28, MaGATA5, MaTALE2, MaARF4, MaSBP1 and MaSBP12, were upregulated under both hormone treatments. Collectively, these findings indicate that exogenous JA and SA treatments elicited overlapping yet distinct defense-related responses in mulberry. This work provides an integrated physiological and transcriptomic framework for the future development of hormone-mediated strategies against G. pyloalis in sericulture.
Sheraz Ahmad, Rahat Sharif, Xiao-Tong Feng et al.· Horticulturae· 0 citations
Fusariumoxysporum f. sp. cubense race 4 (Foc 4) causes Fusarium wilt by penetrating root cell walls, yet the molecular basis of cell wall-mediated resistance remains poorly understood. Here, we investigated the transcriptional, enzymatic, and cellular responses of the resistant banana cultivar Dongjiao No. 1 (DJ) and its susceptible mutant ke2 following Foc 4 infection. RNA sequencing revealed that DJ specifically upregulated a pectin degradation cassette comprising pectin methylesterase (PME3-Like), pectin acetylesterase (PAE1), and polygalacturonases (PG1, PG3, PG5, PG-Like-4) at the bud seedling stage. Immunolocalization further revealed robust, tissue-specific PME deployment, with stable abundance at the primary infection site and differential redistribution in aerial tissues. This enzymatic cascade degraded homogalacturonan, confirmed by the simultaneous loss of pectin epitopes recognized by JIM5 and JIM7 antibodies. Additionally, the upregulation of PTI1, MAPK cascades, calcium-dependent protein kinases (CDPK3, CML31), and respiratory burst oxidase homologs (RBOHs) was also observed in DJ. The differential transcription of salicylic acid signaling (TGA1–PR1), jasmonic acid derepression (TIFY/JAZ), and flavonoid phytoalexin biosynthesis in DJ further reinforced the defense response. In contrast, ke2 failed to activate the pectin degradation machinery, exhibited attenuated immune signaling, and retained intact pectin vulnerable to pathogen exploitation. These findings establish pectin degradation-mediated immunity as a resistance mechanism in banana and provide potential targets for Fusarium wilt resistance breeding.
Rahat Sharif, Yanqing Xing, Huimin Song et al.· Current Issues in Molecular...· 0 citations
A genome-wide identification and comprehensive analysis of the MaTIFY gene family in Musa acuminata provides novel insights into the evolutionary dynamics and stress-responsive functions of banana TIFY genes and identifies candidate targets for molecular breeding to improve abiotic and biotic stress resilience in banana.
Sheraz Ahmad, Huimin Song, Hangbo Cao et al.· International Journal of Mol...· 0 citations
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