Abstract:

The present study was conducted to investigate functions of GmPDAT1（phospholipid: diacylglycerol acyltransferase）genes in soybean oil biosynthesis and abiotic stress response, providing a new scientific reference for soybean oil improvement and stress resistance molecular breeding. The omics tools were employed to GmPDAT1 genes in soybean. Quantitative real-time RT-PCR was used to examine expression patterns of GmPDAT1 genes in various tissues and under three abiotic stresses. Functional complementarity assay was performed with TAG-deficient yeast（Saccharomyces cerevisiae）mutant H1246. Six soybean GmPDAT1 gene family members（GmPDAT1-A-GmPDAT1-F）were identified. GmPDAT1-F had eight exons while the remaining five GmPDAT1 genes contained six exons. Multiple stress-responsive cis- elements were detected in GmPDAT1 promoter regions. The sequence length of GmPDAT1-encoded proteins was between 582-668 aa and their isoelectric point（pI）proteins ranged from 5.91 to 8.59. All GmPDAT1 proteins had PLN02517 superfamily protein domains, classifying as the membrane-binding proteins. The secondary structure of GmPDAT1 proteins mainly consisted of α-helix and ranclom coiled coil. The six GmPDAT1 proteins were phylogenetically clustered into three subgroups, which were closely related to Arachis hypogaea AhPDAT1, Jatropha curcas JcPDAT1 and Ricinus communis RcPDAT1-2, respectively. The members of GmPDAT1 gene family had tissue-specific expression patterns. Of them, GmPDAT1-B was expressed in various tissues with the highest expression in developmental seeds, suggesting that GmPDAT1-B may function crucially for TAG biosynthesis in soybean seeds. Functional complementarity assay using TAG-deficient yeast（Saccharomyces cerevisiae）mutant H1246 evidenced that GmPDAT1-B had the high enzyme activity to catalyze TAG synthesis. Under the treatment of low temperature, drought and salt stress, GmPDAT1 gene members demonstrated different expression patterns, indicating that they differentially participated in different stress responses in soybean. In particular, GmPDAT1-B possibly mediates soybean responses to the three different stresses. In conclusion, GmPDAT1-B may have dual functions in promoting soybean oil synthesis and stress resistance.

Key words: soybean（Glycine max）, phospholipid: diacylglycerol acyltransferase1（PDAT1）, expression analysis, TAG biosynthesis, abiotic stress