Functional analysis of RCD-SRO (Radical-induced cell death - similar to RCD-One) related genes from tomato (Solanum lycopersicum L.) in salt stressed roots

JWL-26 is a novel salt-regulated gene from Solanum lycopersicum L. that shares similarity with several Arabidopsis proteins including RCD1 (Radical-induced Cell Death 1) and SRO (Similar to RCD-One). These proteins regulate hormone signalling cascades involved in programmed cell death. JWL-26 shares the highest amino acid sequence similarity with SRO5, which is expressed in a salt-responsive manner in Arabidopsis and is proposed to protect cells from reactive oxygen species (ROS). In tomato JWL-26 was expressed exclusively in salt-stressed roots. To determine whether JWL-26 is involved in protecting salt-stressed roots against ROS, JWL-26 together with SRO5 were analyzed in transgenic plants. Transgenic lines were generated that over-expressed SRO5 or JWL-26 in wild-type Arabidopsis and in an sro5 knock-out line. Over-expression of SRO5 or JWL-26 improved survival during salt stress and reduced levels of ROS. Thus, JWL-26 may be involved in ROS detoxification pathways in roots and this may confer salt tolerance.