Regulates Drought Tolerance via the Alternative Splicing of Target Genes.

The emerging evidence has shown that plant serine/arginine-rich (SR) proteins play a crucial role in abiotic stress responses by regulating the alternative splicing (AS) of key genes. Recently, we have shown that drought stress enhances the expression of (also known as ) in Herein, we unraveled the hitherto unknown functions of in drought stress response by comparing the phenotypes, chlorophyll a fluorescence and splicing patterns of the drought-responsive genes of Arabidopsis overexpressors (OEs), homozygous mutants (SALK_052345), and controls (Col-0). Overexpression and loss of function did not result in aberrant phenotypes; however, the overexpression of was positively correlated with drought tolerance and the stress recovery rate in an expression-dependent manner. Moreover, OEs showed a higher drought tolerance index during seed germination (38.16%) than the control lines. Additionally, the overexpression of induced the expression of the drought stress-inducible genes , and under normal conditions. To further illustrate the molecular linkages between and drought tolerance, we investigated the AS patterns of key drought-tolerance and interacting genes in OEs, mutants, and controls under both normal and drought conditions. The splicing patterns of and were different between overexpressors and mutants under normal conditions. Furthermore, drought stress altered the splicing patterns of , -, and between OEs and mutants, indicating that both overexpression and loss of function differently influenced the splicing patterns of target genes. This study revealed that regulates the drought stress response via the alternative splicing of target genes in a concentration-dependent manner.