Role of Glycine max ABSCISIC ACID INSENSITIVE 3 (GmABI3) in lipid biosynthesis and stress tolerance in soybean

Soybean is an important oilseed crop and primary dietary protein resource. The limited understanding of soybean oil biosynthesis has become a significant obstacle for the improvement of soybean oil production. A transcription factor ABSCISIC ACID INSENSITIVE 3 (ABI3) is known for its role in plant development and seed dormancy in many crops. The current study was aimed to functionally characterise ABI3 homologue in Glycine max L. For this purpose, the GmABI3 gene was cloned and ectopically expressed in wildtype and abi3 mutant Arabidopsis. The GmABI3 expression in the atabi3 mutant enhanced the triacylglycerol (TAG) content (7.3%) in addition to modified fatty acid composition. The GmABI3 increased eicosenoic acid (20:1) up to 6.5% in genetically complemented Arabidopsis mutant seeds, which is essential for long-chain fatty acid synthesis. The transgenic GmABI3/wildtype seeds contain 34.9% more TAG content compared with wildtype seeds. The results showed that GmABI3 is responsible for seed-specific TAG and long-chain fatty acid biosynthesis in soybean. The exposure to cold and heat stress and exogenous supply of abscisic acid and jasmonic acid altered the level of GmABI3 in treated seeds and leaves. It also concluded that GmABI3 could regulate stress tolerance in soybean, which applies to a wide variety of crops to deal with biological stresses.