Quantitative proteomics reveals an important role of GsCBRLK in salt stress response of soybean

Salinity is one of the serious environmental stresses limiting crop growth and yield. We have previously reported that GsCBRLK functions as a positive regulator of plant tolerance to salt stress. In order to investigate the physiological and molecular mechanisms underlying the salinity tolerance regulated by GsCBRLK, this gene was overexpressed in soybean plants. Here we examined the salt-responsive proteomes of the GsCBRLK overexpression soybean and wild type plants using iTRAQ-based proteomic approach to investigate the global effects and potential downstream targets of GsCBRLK. A total of 941 proteins showed significant changes in protein abundance in soybean leaves, and 574 of the NaCl-regulated proteins were GsCBRLK-dependent. Among the identified proteins, four protein changes in the two genotypes after NaCl treatment were validated using Western blot analysis, at the same time, transcriptional leves of 10 proteins related to Ca2+ signaling were detected using qRT-PCR analysis. Identification of the salt-reponsive proteins has revealed the involvement of GsCBRLK protein in the enhancement of ROS scavenging and photosynthesis capacity in soybean, which was corrobarated with the physiological effects of GsCBRLK overexpression. More importantly, the proteomic data has suggested the regulatory function of GsCBRLK in salt signal transduction pathway mediated by Ca2+/CaM. These findings have contributed to our knowledge of plant GsCBRLK mediated salt tolerance mechanisms.