Comprehensive analysis of GGCT genes in u’s triangle Brassica species: insights into abiotic stress responses and potential association of BnaGGCT11/26 with seed weight

Background: Glutathione homeostasis, crucial for plant growth and stress adaptation, is regulated by the enzyme γ-glutamylcyclotransferase (GGCT). As the critical component of the glutathione recycling pathway, GGCT plays a vital role in maintaining cellular redox balance under normal and stressful conditions. While the GGCT gene family has been characterized in Arabidopsis thaliana, its diversity, evolution, and functional roles remain unexplored in the U’s triangle Brassica species, which includes important oilseed crops. Results: We identified and characterized 154 putative GGCT genes in U’s triangle Brassica species (Brassica nigra, 20; Brassica oleracea, 21; Brassica rapa, 18; Brassica juncea, 35; Brassica napus, 31; Brassica carinata, 29). Phylogenetic analysis grouped these GGCTs into three distinct clades, highlighting their structural and motif diversity. The diversity in cis-regulatory elements highlighted their role in growth and stress responses. Expression profiling of BnaGGCT genes revealed their differential expression patterns across the tissues at different developmental stages, such as BnaGGCT11 and BnaGGCT26, which are specifically expressed during late seed development phases. Furthermore, gene expression analysis under hormones and abiotic stresses indicated their contribution in stress responses as confirmed by eight selected BnaGGCT genes under drought and salt stresses. In addition, SNP analysis of BnaGGCT11 revealed a single-nucleotide variant that is significantly associated with seed weight and yield, potentially influencing gene function or translation efficiency. Conclusion: Collectively, this study comprehensively identified GGCTs that enhance our understanding of the functional evolution of the GGCT gene family in U’s triangle Brassica species and lay the groundwork for further research into GGCT-mediated stress responses and seed development. In particular, the seed-specific expression of BnaGGCT11/26 and the SNP in BnaGGCT11 associated with seed weight and yield highlight their potential as candidates for marker-assisted breeding, but future functional validation will be required to substantiate their roles.