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Tissue specific colonization of Phytophthora capsici in Capsicum spp.: molecular insights over plant-pathogen interaction

Abstract:

Root and crown rot (RCR) caused by Phytophthora capsici is present in all crop production areas of pepper and chili worldwide. This pathogen was recently reported at the Pacific coast of Ecuador (province of Manabí), as an etiological agent of wilt and root and crown rot in commercial fields of bell pepper (Capsicum annuum). This study aimed to evaluate the resistance of ten Capsicum spp. genotypes artificially infected with P. capsici and to compare the tissue-specific colonization of P. capsici under greenhouse conditions. Disease intensity, mycelial growth incidence and pathogen DNA content in root and hypocotyl tissues of P. capsici infected Capsicum germplasm was evaluated at 17 days after infection (dai). Results indicated that genotypes Nathalie, ECU-12831, ECU-9129, Código 5, and ECU-1296 were found to be resistant, and ECU-11995, ECU-2254 B, California Wonder, Quetzal and Marcato showed susceptibility to the disease. The amount of pathogen DNA in roots was the only variable that did not correlate with the resistance or susceptibility of the genotypes. In fact, in resistant genotypes the pattern of pathogen DNA content was higher in roots than hypocotyls (but also in the susceptible ECU-11995), while in the susceptible genotypes (e.g. ECU-2254 B, C. Wonder, Quetzal and Marcato) showed the opposite pattern. The present work provides new insights of host-pathogen interaction, which might be used in breeding programs aiming to develop Capsicum cultivars with resistance to RCR.