Abstract
This work aimed to evaluate the relative gene expression of the candidate genes psI, psII, isr, utp, and prk involved in the defense response to Black Sigatoka in banana cultivars Calcutta-4, Krasan Saichon, Grand Nain, and Akondro Mainty, by a quantitative real-time PCR. Biotic stress was imposed on 6-month-old plants during five sampling intervals under greenhouse conditions. The psII and isr genes were upregulated for the Calcutta-4- and Krasan Saichon-resistant cultivars, and were validated in this study. For Grande Naine, a susceptible cultivar, there was an early downregulation of the psI, psII, and isr genes and a late upregulation of the psII gene. There was no significant expression of any of the genes for the susceptible cultivar Akondro Mainty. Computational biology tools such as ORFFinder and PlantCARE revealed that the utp gene has more introns and exons and that, in general, cis-elements involved in the response to biotic stress, such as as-1, w-box, and STRE, were detected in the promoter region of the genes studied. Data from this work also support the phenotyping studies of banana cultivars affected by Black Sigatoka in the field. Once validated in promising new hybrids, these genes may be used in marker-assisted selection (MAS) and/or gene-editing techniques.