Differential proteomics and functional characterization of PR4 proteins in Oryza sativa acting as a defense pathway to biotic stresses

Abstract

Plants have evolved defense responses to combat a wide range of biotic stresses. However, many pathogens cross the initial barriers and thus plants must have an alternative defense approach. One of these defense mechanisms is the pathogen-induced response, which includes a hypersensitive response and, eventually, the production of PR proteins. These proteins minimize the burden of pathogens or the appearance of disease in uninfected plant organs. Among the PR proteins, PR4 has been shown to be important for being highly effective in protecting sugarcane plants challenged by pathogens and diseases. Rice (Oryza sativa) is an important food crop and a model species for monocotyledonous plants, but the understanding of PR4 proteins in this species is relatively limited. Rice crops are affected by diseases throughout their cycle. Brusone, caused by the fungus Magnaporthe oryzae, is a severe fungal disease, difficult to control and recurrent in all rice producing regions in the world. In addition, F. verticillioides is one of the main pathogens that infect rice seeds, causing stem base rot. Among the caterpillars, Diatraea saccharalis is considered an economically important pest and affects grasses in different cropping systems. Therefore, the aim of this study is to obtain the differential proteome of rice genotypes contrasting with Brusone disease as well as to characterize the functionality of PR4 proteins in rice plants subjected to different types of biotic stresses via infection by Magnaporthe oryzae and/or injury caused by Diatraea saccharalis associated or not with Fusarium verticillioides. For this, the gene expression of the four copies of PR4 in sensitive and tolerant rice genotypes will be analyzed, the possible enzymatic activities (Ribonuclease, deoxyribonuclease, chitosanase and chitinase) of PR4 proteins will be quantified and the production of volatiles by plants will be quantified. In addition, the differential proteomics of contrasting genotypes to infection by Magnaporthe oryzae will be performed and the action potential of PR4 recombinant rice proteins under Fusarium verticillioides associated with Diatraea saccharalis will be analyzed. (AU)