The citrus industry is one of the most important agribusinesses in Brazil, especially in world production of orange juice. However, due to phytosanitary problems, there was an increase in the cost of production and consequent decrease in planted area providing lower yields than expected. Some diseases fall into this context and one of them is the Citrus Variegated Chlorosis (CVC), caused by the bacterium Xylella fastidiosa, which had its genome sequenced so that their biology were better known. Among many studies which followed, it was found that this bacterium has operons encoding the toxin-antitoxin (TA) system. These functions are passing from the maintenance of plasmids to regulatory responses to modulation key genes for bacterial adaptation to adverse conditions in the environment. For example, overexpression of MqsR toxin (a ribonuclease which degrades mRNAs with motifs GCU) in X. fastidiosa induces an increase in biofilm formation, cell movement repression and lack of pathogenicity in plants. Further, increase in the expression levels of MqsR toxin was observed when exposed to X. fastidiosa was copper, an antimicrobial compound, producing changes in cells, such as inducing the formation of persistent cells. These are physiological variants of the cell and are able to survive even when exposed to lethal levels of toxic compounds. The detailed mechanism by which this process occurs is not yet fully known, it is therefore of great interest to identify target sequences of genes regulated by MqsR toxin, so that they can better understand the role of this toxin in gene regulation and induction persistent cells in X. fastidiosa.
News published in Agência FAPESP Newsletter about the scholarship: