Development of RNAi induction system to silence candidate genes of phytopathogenic citrus fungi

Abstract

Brazil is responsible for a third of world production of orange, as well as for 80% of international orange juice market. The European Union is the main market in this Brazilian agrobusiness. However, losses in the export of fruits occur because of A1 quarantine diseases, causing restrictions on the importation of Brazilian citrus products into European countries. One of these diseases is the Citrus Black Spot caused by the fungus Phyllosticta citricarpa (Guignardia citricarpa). Other fungus the Colletotrichum acutatum, responsible for postbloom fruit drop (PFD) citrus disease, causes serious losses in citrus fruit production. Many works are being developed to study and control these phytopathogenic fungi. A currently and promising approach is the study of the gene expression by knockout or knockdown, using RNA interference (RNAi). Such sequences can be found by genome and transcriptome analysis or by silencing of gene involved in phenotypic characteristics due an insertion of exogenous DNA fragment in expressed region in the genome of the interested organism. Thereby, RNAi tools are very important to support the study of disease mechanisms used by phytopathogens fungi. Therewith, the goals of this work are to apply the RNAi methodology, generating of dsRNA by convergent transcription, using the regions previously silenced due the T-DNA insertion (Agrobacterium tumefaciens-mediated transformation). Thereunto, in the period abroad, the A. tumefaciens vectors will be constructed, the phytopathogens will be transformed and the characteristics will be evaluated as the silencing due the RNA interference in both fungi. (AU)