Evolutionary Expansion and Diversification of the GDSL Gene Family in Grasses

The glycine-aspartic acid-serine-leucine (GDSL) esterase/lipase family is a functionally diverse group of hydrolytic enzymes involved in multiple plant biological processes, including stress adaptation and development. However, its evolutionary patterns, functional conservation, and stress-responsive mechanisms in grasses remain not fully elucidated. In this study, a comprehensive comparative genomic analysis was performed on the GDSL gene family across nine representative grass species and Arabidopsis thaliana. Genome-wide identification, phylogenetic analysis, duplication pattern detection, synteny analysis, cis-regulatory element prediction, protein–protein interaction (PPI) network construction, and RNA-seq-based expression profiling were employed. A total of 1707 GDSL genes were identified, with substantial expansion in grasses, especially hexaploid wheat. Whole-genome and segmental duplications were the major drivers of family expansion, with most duplicated genes under strong purifying selection. A grass-specific clade (C3-2) was identified, and extensive syntenic conservation was observed among closely related grasses. Promoter analysis revealed enrichment of stress- and hormone-responsive cis-elements, and RNA-seq showed dynamic GDSL expression under low-temperature stress in rice and wheat. These findings demonstrate that the expansion of the GDSL gene family in grasses is driven by polyploidization and lineage-specific duplication, accompanied by the emergence of a grass-specific clade (C3-2) and regulatory diversification, collectively shaping stress-responsive evolutionary innovation in Poaceae.