Regulation of Drought and Salt Tolerance by OsSKL2 and OsASR1 in Rice.

Abiotic stresses such as salinity and drought greatly impact the growth and production of crops worldwide. Here, a shikimate kinase-like 2 (SKL2) gene was cloned from rice and characterized for its regulatory function in salinity and drought tolerance. OsSKL2 was localized in the chloroplast, and its transcripts were significantly induced by drought and salinity stress as well as HO and abscisic acid (ABA) treatment. Meanwhile, overexpression of OsSKL2 in rice increased tolerance to salinity, drought and oxidative stress by increasing antioxidant enzyme activity, and reducing levels of HO, malondialdehyde, and relative electrolyte leakage. In contrast, RNAi-induced suppression of OsSKL2 increased sensitivity to stress treatment. Interestingly, overexpression of OsSKL2 also increased sensitivity to exogenous ABA, with an increase in reactive oxygen species (ROS) accumulation. Moreover, OsSKL2 was found to physically interact with OsASR1, a well-known chaperone-like protein, which also exhibited positive roles in salt and drought tolerance. A reduction in ROS production was also observed in leaves of Nicotiana benthamiana showing transient co-expression of OsSKL2 with OsASR1. Taken together, these findings suggest that OsSKL2 together with OsASR1 act as important regulatory factors that confer salt and drought tolerance in rice via ROS scavenging.