Proteomic Analysis of a Rice Mutant Possessing a Novel Allele of Heterotrimeric G Protein Alpha Subunit (RGA1) in Salt Stress with a Focus on ROS Scavenging.

High salinity severely restrains plant growth and results in decrease of crop yield in agricultural production. Thus, it is of great significance to discover the crucial regulators involved in plant salt resistance. Here, we report a novel mutant, , which displays enhanced salt tolerance and dwarf phenotype, by screening from ethyl methane sulfonate (EMS) mutagenized rice mutant library. Genetic analysis showed that was caused by a single recessive locus. Map-based cloning and allelic test revealed that the phenotypes of were due to the mutation of , encoding the alpha subunit of heterotrimeric G protein (G). A point mutation (G to A) was identified at the splicing site (GT-AG) of the first intron in , which gives rise to the generation of abnormal mRNA splicing forms. Furthermore, 332 differentially abundant proteins (DAPs) were identified by using an Isobaric Tags for Relative and Absolute Quantitation(iTRAQ)-based proteomic technique from seedlings of and Kitaake in response to salt treatment. Gene Ontology (GO) and KEGG pathway enrichment analysis revealed these proteins were mainly involved in regulation of the processes such as metabolic pathways, photosynthesis and reactive oxygen species (ROS) homeostasis. Under salt stress, displayed lower ROS accumulation than Kitaake, which is consistent with the higher enzyme activities involved in ROS scavenging. Taken together, we propose that RGA1 is one of the regulators in salt response partially through ROS scavenging, which might be helpful in elucidating salt tolerant mechanisms of heterotrimeric G protein in rice.