Gene expression analysis of the Xanthomonas citri subsp citri type VI secretion system

Abstract

Members of the Xanthomonas genus are plant-associated bacteria and include some important pathogens of crops, which cause severe economic impacts on agriculture. More specifically, Xanthomonas citri subsp. citri (Xac) causes citrus canker, a disease that results in big economic losses in Brazil and other countries throughout the world. Thus, it is highly important to elucidate the mechanisms involved in citrus canker pathogenesis and infection, helping to avoid the economic losses that result from this phytopathology. Bacterial secretion systems (SS) translocate effector proteins to target cells and are involved in virulence and other functions, including increasing the bacterial fitness in interespecies interactions. Type VI secretion systems (T6SS) were recently identified in gram-negative bacteria and genes coding for a complete T6SS are found in the Xac genome. Considering the importance of SS for bacterial physiology, the elucidation of Xac T6SS function will improve our understanding of Xac biology and provide new insights into this new group of SS. This project aims at the analysis of expression and regulation of T6SS genes in Xac, providing important clues to understand the function of this SS. For that, we will analyze the activity of a promoter found upstream of T6SS genes in Xac during growth and under distinct conditions of interest. Also, we will study the expresssion of selected T6SS genes during Xac interaction with host plants, using RT-qPCR. The results obtained in this project will complement other functional studies of the Xac T6SS currently in progress in the laboratory.