Pea p68 Imparts Salinity Stress Tolerance in Rice by Scavenging of ROS-Mediated H2O2 and Interacts with Argonaute

The p68, a prototypic member of DEAD-box protein family, is involved in pre-mRNA splicing, RNA-induced silencing and transcription regulation. However, the role of plant p68 in stress tolerance and molecular targets responsible for this has not been reported. Here, we report the isolation and characterization of salinity-induced pea p68 (Psp68). The expression of Psp68 was more in aerial parts as compared to the roots in response to the abiotic stress. The transgenic-overexpressing Psp68 showed enhanced tolerance to salinity stress by efficiently attenuating ionic adjustment and scavenging reactive oxygen species (ROS). The enhanced tolerance was further confirmed by observing several physiological indices. Psp68-overexpressing rice accumulated higher K+ and Ca2+ and lower Na+ level as compared to the wild-type (WT) plants. Furthermore, Psp68 interacts with pea argonaute (AGO1), a catalytic component of the RNA-induced silencing complex (RISC) responsible for the gene silencing. The microarray analysis showed that Psp68 regulates many transcripts involved in the abiotic and oxidative stress responses as well as gene-silencing mechanisms in rice. Thus, the Psp68 functions as a molecular switch in different signaling pathways leading to stress tolerance. Overall, Psp68 may serve as a useful biotechnological tool for the improvement of stress tolerance crops.