Innovative strategies aimed resistance to bacterial leaf spot of tomato.
S Genes, Knockout, PR Protein, Overexpression
The disease bacterial leaf spot of tomato (Solanum lycopersicum L.) is caused by three species, including Xanthomonas euvesicatoria pv. euvesicatoria, X. euvesicatoria pv. perforans, X. vesicatoria and X. hortorum pv. gardineri. The disease is difficult to control and requires the use of copper-based products. However, the continuous use of these products selects resistant populations of the pathogen, reducing the efficiency of disease control. Another factor that makes bacterial leaf spot control difficult is the lack of resistant cultivars, as the targeting strategies of acquiring resistance involve mostly resistance genes (R genes) which can lead to the development of new races of the pathogen capable of overcoming resistance. Thus, new resistance strategies targeting the knockout of resistance genes (S genes) and the overexpression of defenserelated genes may be efficient alternatives to provide basal resistance against multiple pathogens. From this perspective, the objective of this work is to develop new strategies for controlling the bacterial leaf spot of tomato, through the knockout of an S-gene and the overexpression of a gene related to plant defense. To select an S gene as a knockout candidate, the expression of S genes during the interaction between X. euvesicatoria pv. perforans and susceptible plants of S. lycopersicum cv. Santa Cruz will be analyzed by RT-qPCR. An S gene with increased expression will be selected as a candidate for the knockout by CRISPR/Cas9. The defense gene encoding endochitinase from Brassica oleracea was previously studied and demonstrated to confer resistance against Xanthomonas in Arabidopsis thaliana and selected for overexpression in S. lycopersicum cv. MicroTom to assess plant resistance against X. euvesicatoria pv. perforans. It is expected that the identification of S genes in tomato will allow its knockout and promote resistance or tolerance against the bacteria, the same goes for the overexpression of the defense gene.