Genome-Wide Identification, Evolution, and Expression of GDSL-Type Esterase/Lipase Gene Family in Soybean

Abstract

GDSL-type esterase/lipase proteins (GELPs) belong to the SGNH hydrolase superfamily and contain a conserved GDSL motif at their N-terminus. GELPs are widely distributed in nature, from microbes to plants, and play crucial roles in growth and development, stress responses and pathogen defense. However, the identification and functional analysis of <i>GELP</i> genes are hardly explored in soybean. This study describes the identification of 194 <i>GELP</i> genes in the soybean genome and their phylogenetic classification into 11 subfamilies (A-K). <i>GmGELP</i> genes are disproportionally distributed on 20 soybean chromosomes. Large-scale WGD/segmental duplication events contribute greatly to the expansion of the soybean <i>GDSL</i> gene family. The Ka/Ks ratios of more than 70% of duplicated gene pairs ranged from 0.1-0.3, indicating that most <i>GmGELP</i> genes were under purifying selection pressure. Gene structure analysis indicate that more than 74% of <i>GmGELP</i> genes are interrupted by 4 introns and composed of 5 exons in their coding regions, and closer homologous genes in the phylogenetic tree often have similar exon-intron organization. Further statistics revealed that approximately 56% of subfamily K members contain more than 4 introns, and about 28% of subfamily I members consist of less than 4 introns. For this reason, the two subfamilies were used to simulate intron gain and loss events, respectively. Furthermore, a new model of intron position distribution was established in current study to explore whether the evolution of multi-gene families resulted from the diversity of gene structure. Finally, RNA-seq data were used to investigate the expression profiles of <i>GmGELP</i> gene under different tissues and multiple abiotic stress treatments. Subsequently, 7 stress-responsive <i>GmGELP</i> genes were selected to verify their expression levels by RT-qPCR, the results were consistent with RNA-seq data. Among 7 <i>GmGELP</i> genes, <i>GmGELP28</i> was selected for further study owing to clear responses to drought, salt and ABA treatments. Transgenic <i>Arabidopsis thaliana</i> and soybean plants showed drought and salt tolerant phenotype. Overexpression of <i>GmGELP28</i> resulted in the changes of several physiological indicators, which allowed plants to adapt adverse conditions. In all, <i>GmGELP28</i> is a potential candidate gene for improving the salinity and drought tolerance of soybean.