"Innovative strategies aimed at resistance to bacterial spot of tomato".
S Genes, Knockout, PR Protein, Overexpression, Xanthomonas euvesicatoria pv. perforans
Bacterial spot is one of the major diseases of tomato (Solanum lycopersicum L.) that reduces production. The main disease control measures use products that increase production costs and are harmful to the environment. In this context, this study aimed to develop innovative disease control strategies that overcome these difficulties. First, gene expression related to tomato susceptibility to Xanthomonas euvesicatoria pv. perforans (Xep) was studied, as well as the gene silencing of the Transcription initiation factor IIA subunit 2 (gamma) (SlTFIIAγ) by ASO (short antisense deoxyoligonucleotide). The results of the SlTFIIAγ gene silencing demonstrated that treatment with ASO promoted enhanced performance of plants infected with Xep, and therefore, the gene was selected for evaluation of knockout using CRISPR/Cas9. The knockout revealed that gene editing occurred in seven T0 lines, five of which were biallelic and two chimeric. Another control strategy studied was the overexpression in tomato of a defense gene from Brassica oleracea that encodes an endochitinase. The T2 transgenic lineages were subjected to an Xep resistance assay, and no resistance response could be observed. Additionally, plants were inoculated with the fungus Sclerotinia sclerotiorum and the results showed that two transformation events demonstrated greater capacity to support the initial growth of the fungus. This may be related to the action of chitinase on the fungal cell wall. Furthermore, the work searched for new potential genes related to susceptibility using proteomics approach. Nine proteins that potentially contribute to the development of the disease were identified. The differentially abundant proteins were mainly related to sugar transport, stress response, and generation of metabolites and energy. Further studies of these proteins may provide new targets for gene silencing and/or knockout aimed at resistance to bacterial spot.