Prospection of genotypes resistant to black spot in half‐sib families of papaya

Abstract

Papaya (Carica papaya L.) breeding is a complex task; furthermore, Carica papaya has a sexual chromosome and is difficult to make crosses. One of the most critical papaya crop diseases is black spot, which is caused by Asperisporium caricae (Speg.) MaublSince . Therefore, we used half-sib families to combine genetic gains on the yield and resistance traits to papaya black spot. In this scenario, the present study proposed to select papaya genotypes more resistant to black spot from half-sib families.Five parents with superior attributes related to black spot resistance were pollinated with a pollen mixture from five parents considered "elite" for agronomic traits, thus generating five half-sib families. The half-sib families were evaluated for black spot resistance in a greenhouse with two control cultivars ('Golden' and 'Maradol'), for 75 d, at 15-d intervals, totaling five evaluations. The families exhibited genetic variability for all traits associated with disease resistance, surpassing even the Golden and Maradol controls. The traits associated with severity by papaya black spot are more efficient to distinguish resistance genotypes using principal components analysis, like mean incidence of black spot (MSBS) (cosš = 0.794) and area under the disease progress curve (AUDPC) (cosš = 0.697). The recommended progeny for resistance to black spot are M-1.4, M-1.5, M-3.1, M-3.3, M-2.5, and M-4.5, as they showed lower values of mean severity of black spot, MIBS, and AUDPC. These progenies from half-sib families overcame the resistant control genotype Maradol as potential to combining resistance to papaya black spot with superior agronomic traits. INTRODUCTIONBlack spot, caused by the fungus Asperisporium caricae (Speg.) Maubl, is a disease of high economic relevance for the papaya crop (Carica papaya L.) worldwide. The disease Abbreviations: AUDPC, area under the disease progress curve; MIBS, mean incidence of black spot; MSBS, mean severity of black spot.