Genome-wide characterization of monoacylglycerol lipase (MAGL) gene family in soybean and functional analysis of GmMAGLs in storage lipid metabolism and drought resistance.

BACKGROUND

Monoglyceride lipase (MAGL) catalyzes the final step of triacylglycerol (TAG) hydrolysis, converting monoacylglycerol (MAG) into glycerol and free fatty acids. Although MAGL is critical for TAG metabolism, its physiological roles in plants remain poorly understood, compared to its functions in mammals.

RESULTS

Eighteen GmMAGL genes were identified from the genome of soybean (Glycine max), a major food and oil crop worldwide, with them being classified into 8 distinct subfamilies. Collinearity analysis indicated that segmental duplication was the only force driving GmMAGL gene family expansion. Multiple sequence alignment demonstrated that all 18 GmMAGLs harbored two typical structural features: the lipase GXSXG (Gly-X-Ser-X-Gly) motif and the catalytic triad consisting of Ser, Asp and His residues. Notably, GmMAGL14 and GmMAGL15 harbored an additional acyltransferase motif, distinguishing them as the only two bifunctional enzymes (hydrolase and acyltransferase) within the GmMAGL family. Additionally, multiple cis-elements associated with development, hormone, and stress response were identified in the promoter regions of GmMAGL genes. RNA-seq data revealed that GmMAGL genes displayed tissue-specific or distinct expression patterns in response to abiotic stresses and hormone treatments. Remarkably, the expression of GmMAGL10 and 14 was negatively related to oil accumulation during seed development while GmMAGL3 exhibited high expressions during seed germination. Particularly, 6 GmMAGL genes (GmMAGL1/3/4/6/8/12) showed significant modulation in response to drought stress in roots and leaves of soybean seedlings.

CONCLUSIONS

This study represents the first comprehensive identification of 18 members of GmMAGL gene family in soybean. GmMAGL10 and 14 may impact seed oil content negatively while GmMAGL3 function importantly in seed germination. GmMAGL1/3/4/6/8/12 might confer drought tolerance by activating lipid metabolism in soybean seedlings. The present data establish a foundation for further elucidation of the biological functions of GmMAGL genes and provide valuable target genes for genetic improvement in soybean and other crops.