Hot pepper (Capsicum chinense, Jacq.) inheritance of reaction to powdery mildew

Abstract

The pepper species C. chinense has been considered one of the most important resistance sources to powdery mildew Capsicum spp. However, the inheritance in this species was unknown. The purpose of this work was to study its reaction inheritance. Two powdery mildew resistant parents, 'Pimenta Cheiro' 1 and PI 152225 and two moderately susceptible ones, 'Pimenta Doce' IH-1761 and 'Pimenta Índio', were used to obtain three F1 and their respective F2 generations: 'Pimenta Doce' IH-1761 <FONT FACE=Symbol>´</FONT> 'Pimenta Cheiro' 1, 'Pimenta Índio' <FONT FACE=Symbol>´</FONT> PI 152225 and 'Pimenta Doce' IH-1761 <FONT FACE=Symbol>´</FONT> PI 152225. The powdery mildew epidemy was natural using inoculum from a highly-sporulating susceptible pepper host. Powdery mildew host reaction evaluations were carried out during the fruiting stage using a rating system based on disease severity scales varying from 1 (resistant) to 5 (highly susceptible). The experimental design was completely randomized. The following genetic parameters were estimated: gene action, heritability coefficient and expected selection gain in the F3 generation. The transgressive segregation in F2 indicated oligogenic inheritance. Results show the presence of additive, dominant, and epistatic gene action. The dominant and epistatic effects detected in crosses presented negative values, tending towards susceptibility. The heritability and selection gain estimates were moderate, with values of 35.5% and 1.7% for 'Pimenta Doce' IH 1761 <FONT FACE=Symbol>´</FONT> 'Pimenta Cheiro' 1, from 50.4% to 3.5% for 'Pimenta Índio' <FONT FACE=Symbol>´</FONT> PI 152225, and 49% and 2.7% for the 'Pimenta Doce' IH 1761 <FONT FACE=Symbol>´</FONT> PI 152225 crosses, respectively. These gene action results are favorable for breeding programs and exploration of hybrids.