Analysis of expression and mutagenesis of a pathogenicity mechanism from Xanthomonas axonopodis pv. citri: the type II secretion system

Abstract

The citrus canker is, certainly, one of the most destructive diseases of plants worldwide, especially in those countries where the citrus industry plays a strategic role that results in job and incomes, which includes Brazil, the greatest orange producer. Therefore, Brazil sponsored the sequencing of the causal agent of citrus canker, the bacterium Xanthomonas axonopodis pv. citri (Xac). The objective of this work was to genetically identify the biological tools that the bacterium harbors and that utilizes during the infection of citrus plants. Thus, the prospects are to better understand how the bacterium acts and, therefore, identify targets for the management of the disease. During its complete sequencing, various secretory systems were identified, which are highly related to pathogenesis. These systems include the "type two secretory system" (T2SS), which in other plant bacterial pathogens is involved in the process of infection. Strikingly, in Xac, there are two distinct copies of the T2SS - which is not frequent in other bacteria. However, to our knowledge, there is no study that investigated the role played by these systems in the occurrence of citrus canker. The goal of thei study is to characterize the expression of the two copies of the T2SS in Xac during the infection. To perform the characterization, the expression will be monitored by RT-qPCR along with the technique of mutagenesis. Finally, the aim is to identify the correlation - if there is any - between the two T2SS and how they contribute to the citrus canker to succeed. (AU)