Genome-wide characterization and expression divergence of germin-like protein (GLP) family in upland cotton (Gossypium hirsutum L.) in response to abiotic stress conditions

Cotton ( Gossypium hirsutum L.) is a major fiber crop that serves as the foundation of the global fiber industry. Abiotic stresses (including drought, high temperature, and salinity) have become prevalent due to climate change. Several gene families involved in various physiological, hormonal, and molecular processes are crucial for enhancing plants’ ability to adapt to environmental constraints. Germin-like proteins (GLPs) constitute a conserved gene family that plays important roles in plant defense and responses to biotic and abiotic stresses. Furthermore, GLP genes belong to the Cupin superfamily, which has not yet been studied in cotton. Hence, the current study investigated the GLP gene family in cotton and identified 32 GLP members. Various analyses were conducted to thoroughly investigate the functions of GhGLP genes in cotton plants’ stress responses. The sequences of GLP members were retrieved from monocots, eucots, model, and primitive organisms to predict the lineage and conserved behavior in cotton and other plant species through phylogeny. This was supported by motif, domain, and gene-structure analyses. In addition, intra- and inter-chromosomal gene duplications were confirmed using a comprehensive analysis of circular and linear collinearity. Digital gene expression data were used to predict highly upregulated genes under drought, high-temperature, and salt stresses, and the expression levels were further validated by qRT-PCR. The GhGLP genes, including GhGLP2 , GhGLP3 , GhGLP12 , GhGLP19 , and GhGLP25 , were upregulated with higher transcript abundance in cotton under stress conditions.