RESISTANCE TO Phytophthora capsici LEO. IN HUACLE PEPPER (Capsicum annuum L.) LINES

Abstract

Among the major diseases of chili pepper cultivation is the “wilting” (Phytophthora capsici L.). As in other diseases, genetic resistance is an important strategy for its control. One of the sources where resistance genes can be found are local landraces. Huacle pepper accessions with resistace to this pathogen have been found in previous collections. In the present study, the inheritace of resistance to P. capsici of Huacle pepper lines 33.3, 34.1 and 35.3 was determined. F₂ populations were generated from crosses of the three lines with the susceptible variety NuMex Joe E. Parker. The determination of similarity between the resistance genes of lines 33.3 and 35.3 was accomplished through direct and reciprocal crosses between them and F₂ populations were generated. F₂ populations were inoculated with P. capsici isolates which in previous evaluations behaved as avirulent to the three Huacle parental lines and virulent to the susceptible variety. Segregant seedlings in F₂ were classified as resistant or susceptible, according to a severity scale of 1 to 7, and analyzed with a Chi-square test to determine the number of resistant genes present in each line. Lines 33.3 and 35.3 showed a 3:1 segregation ratio of resistant and susceptible seedlings which indicates the presence of a different gen in each line; result that was confirmed by the 15:1 segregation ratio observed in the F2 populations generated from the crosses among these lines. Line 34.1 presented two dominant genes of resistance, due to the 15:1 segregation in the F₂ population between resistant and susceptible plants.