ABA-insensitive (ABI) 4 and ABI5 synergistically regulate DGAT1 expression in Arabidopsis seedlings under stress

•TAG accumulation in Arabidopsis seedlings is an important stress response.•DGAT1 expression in Arabidopsis seedling is induced by stress.•Both ABI4 and ABI5 are important for TAG accumulation in Arabidopsis under stress.•We report a synergistic effect of ABI4 with ABI5 in regulating DGAT1 expression. Triacylglycerol (TAG) accumulation is essential for seed maturation in plants. Diacylglycerol acyltransferase 1 (DGAT1) is the rate-limiting enzyme in TAG biosynthesis. In this study, we show that TAG accumulation in Arabidopsis seedlings is correlated with environmental stress, and both ABI4 and ABI5 play important roles in regulating DGAT1 expression. Tobacco transient assays revealed the synergistic effect of ABI4 with ABI5 in regulating DGAT1 expression. Taken together, our findings indicate ABI5 is an important accessory factor with ABI4 in the activation of DGAT1 in Arabidopsis seedlings under stress.