The proteomic analysis of the resistance responses in tomato during interaction with Alternaria alternate

Abstract

Early blight disease, caused by Alternaria alternate, is one of the main tomato diseases in the world. To better understand the mechanisms involved in tomato resistance to A. alternata, we investigated the comparative proteome profiling using 2-DE and identified differentially expressed proteins (DEPs) by MALDI TOF/TOF MS of the resistance and susceptible tomato cultivars inoculated with A. alternata at 48 and 72 h post-inoculation compared with mock-inoculated ones. Based on the proteomics results, we elected two differentially expressed proteins to validate in way Real-Time PCR. From approximately 650 protein spots detected in tomato cultivars, a total 33 DEPs were identified in response to A. alternate infection. These proteins were grouped into 9 functional categories involving in pathways of stress and defense, photosynthesis, energy, transport, mRNA processing, post transcriptional modification, metabolic process, signal transduction, and other pathways. STITCH database analysis predicted different hormone pathways such as methyl jasmonate, salicylic acid, ethylene and brassinolide involved in defense response upon A. alternate. From 33 DEPs, 8 and 4 proteins were up-regulated at 48 and 72 hpi, respectively, in susceptible cultivar, while 32 proteins were increased at 48 and 72 hpi in resistance cultivar in response to A. alternate infection. Results of Real-Time PCR indicated that the expression levels of candidate genes were in accordance with their protein expression at the related time points. This is the first tomato–A. alternata proteomics analysis, which has provided a better understanding of the molecular mechanisms of the tomato response to A. alternata and can implement genetic biomarkers for improving tomato resistance to early blight disease.