Protection of citrus with antibacterial peptides and gallates

Abstract

Citriculture is one of the main economical activities in Brazil, which is the biggest exporter of concentrate orange juice in the world. The estate of São Paulo is responsible for more than half of the Brazilian orange production. Despite the success, the Brazilian citriculture faces constant threats such as irrigation and nutritional problems, plagues and diseases. Among them, we cite citrus canker, a severe disease caused by the Gram-negative bacterium Xanthomonas citri ssp. citri (X. citri). Currently, there is no treatment for citrus canker and the eradication of affected plants is the only reliable method to contain the spread of the pathogen. From 2017, the legislation concerning the control of citrus canker was modified in the state of São Paulo, and now, it is possible to apply integrated management, having the etiological agent present in the field (endemic). This practice includes the use of less susceptible cultivar of citrus, plantation of windshield separating orchards to prevent the spread of the bacterium and several applications of cupric formulations as bactericides. However, copper is toxic and accumulates in the soil/water reservoirs. Our group is dedicated to the development of environmental sustainable strategies to control citrus canker. Our aims are to generate chemical compounds with lower toxicity, compared to copper, that could be used as agricultural defensives. With the help of FAPESP (FAPESP/NWO 2013/50367-8) we described bacterial inhibitors that have as target the divisional septum of X. citri. The major challenge we have now if to fixate our compounds in the plant tissues in order to effectively protect citrus against X. citri. Recently, our group has joined a German group of material sciences in a new consortium that has as main objective the development of two platforms to immobilize our bacterial inhibitors on the orange trees: immobilization via peptides and microgel. Our proposal was awarded a thematic grant from FAPESP (FAPESP/BMBF 2015/50162-2), and the current proposal for a PhD scholarship contemplates the biological part of the main thematic project. As results, we expect to develop alternatives with lower toxicity than copper for the control of citrus canker. (AU)