Glycogen synthase kinase 3 (GSK3/Shaggy-like) belongs to evolutionarily conserved serine/threonine protein kinases that regulate plant morphological development, multi-hormone crosstalk and adaptation to abiotic stresses. However, systematic genome-wide characterization of CmGSK3 is still absent in melon (Cucumis melo L.). This study identified six CmGSK3 members on a whole-genome level, unevenly distributed among four chromosomes. Combined phylogenetic and synteny profiling separated these six genes into four conserved subclades; orthologous links were discovered between melon, Arabidopsis, and rice, revealing evolutionary conservation between monocot and dicot crops. Prediction of promoter cis-regulatory moti... More
Glycogen synthase kinase 3 (GSK3/Shaggy-like) belongs to evolutionarily conserved serine/threonine protein kinases that regulate plant morphological development, multi-hormone crosstalk and adaptation to abiotic stresses. However, systematic genome-wide characterization of CmGSK3 is still absent in melon (Cucumis melo L.). This study identified six CmGSK3 members on a whole-genome level, unevenly distributed among four chromosomes. Combined phylogenetic and synteny profiling separated these six genes into four conserved subclades; orthologous links were discovered between melon, Arabidopsis, and rice, revealing evolutionary conservation between monocot and dicot crops. Prediction of promoter cis-regulatory motifs combined with transcriptome datasets suggested that CmGSK3 genes participate in hormone transduction and environmental stress adaptation. Quantitative real-time PCR further verified that exogenous brassinosteroid (BR) application dramatically induced transcriptional accumulation of CmSK21 and CmSK22. Heterologous overexpression of these two genes in wild-type Arabidopsis significantly lowered plant sensitivity to BR, confirming they may function as negative modulators of the BR signaling cascade. Collectively, CmGSK3 members coordinate multiple metabolic routes, dominated by BR-related signal transduction, to manipulate melon growth and stress adaptability. This study establishes the first systematic research on the melon GSK3 family and supplies elite candidate genes for molecular breeding targeting fruit quality and stress resistance improvement in melon.
