Functional analysis of S. scitamineum pathogenicity candidate genes in sugarcane

Abstract

Sugarcane is among the main crops in cultivated area and production in the world. Among the aspects that may affect production are the severity of some diseases, which result in the reduction of biomass and its by-products. Among these diseases is sugarcane smut, caused by the fungus basidiomycete Sporisorium scitamineum. The expressive effect of the co-evolution existing between S. scitamineum and sugarcane is evidenced by the formation of the whip, composed of tissues of both organisms. This structure is formed mainly in the smut susceptible varieties, although the colonization of plant tissues by the fungus occurs also in those considered resistant. The losses in production due to the establishment of the fungus are high, due to the redirecting of a large quantity of photoassimilates to the formation of the whip and the alteration of the normal vegetative growth of the apical meristem of the plant. The molecular events leading to the determination of host specificity in plants are poorly understood. With the purpose of evaluating the expression profile of genes related to the development of the fungus in plant at different times in the plant-pathogen interaction, the present study aims to delineate a pattern that can contribute to the understanding of the critical phase of disease development, which is the onset of sporogenesis. The genes selected for this study were identified from the Genomics group's project entitled "Comparative genomics perspective of host specialization by smut fungi" and potentially encode for a diacylglycerol transferase (g5207); a chitin binding protein (g2198); a homeobox transcription factor (g970); and a sporogenesis associated protein (g2159). The expression of these genes will be evaluated by RT-qPCR during the interaction process and in culture medium in an experiment composed of two sugarcane genotypes (susceptible and resistant to smut) during six times of material collection. The amount of the fungus will be monitored using quantitative PCR. Thus, from the results obtained, a better understanding of the patosystem is expected, focusing on the adaptive mechanisms of the fungus, as well as the onset of the sporogenesis. (AU)