Differential expression of SlmiR-168a and SlAGO1 in JZ18 and JZ34
JZ34 tomatoes (low-K+ tolerant) show better root development and K+ absorption ability than JZ18 tomatoes (low-K+ sensitive) under K+deficiency (Zhao et al. 2018). According to our previous miRNA-seq research, SlmiR-168a is differentially expressed between JZ18 and JZ34 tomatoes under K+ deficiency stress. Therefore, in this study, we first performed RT-PCR to show that the expression levels of SlmiR-168a were increased with time in JZ18 tomatoes under normal conditions. However, we found that SlmiR-168a levels were decreased under K+ deficiency with time (Fig. 1a), suggesting that in low K+-sensitive JZ18,SlmiR-168a expression affected the tolerance of tomatoes to K+ deficiency. Corresponding expression patterns were observed for the SlmiR-168a target gene SlAGO1 after treatment for 3 and 5 days (Fig. 1b). However, in JZ34 tomatoes, the expression levels of SlmiR-168a were significantly increased by K+ deficiency, particularly after treatment for 3, 5, and 7 days (Fig. 1c). The target AGO1 expression levels were obviously decreased under K+ deficiency compared with that under normal conditions in JZ34 tomatoes (Fig. 1d). As a target ofmiR-168a , SlAGO1 showed a complementary expression pattern, and the expression of SlmiR-168a actually responded to the low K+ stress. The differential expression patterns of SlmiR-168a between JZ18 and JZ34 tomatoes may be a cause of the variations in tolerance of the two tomato genotypes under low K+ stress.