Prospecting on Passiflora backcross families: implications for breeding aiming at CABMV resistance

Abstract

Passion fruit woodiness disease induced by Cowpea aphid-borne mosaic virus (CABMV) is currently the most harmful viral disease affecting passion fruit crops. Given the economic importance of this fruit crop in Brazil, it is essential that passion fruit breeding programs invest in developing resistant and productive cultivars. The goals of this study were to estimate genetic parameters of agronomic and resistance traits via restricted maximum likelihood (REML) and select individuals found to be resistant to CABMV and agronomically superior, in order to provide the basis for further studies on passion fruit breeding, with the aim to develop cultivars resistant to CABMV. The study was conducted in randomized block design, with four replicates. Three full-sib families from the recombination of RC1 parents were evaluated. Based on the severity data, the area below the mean disease progress curve (AUDPCM) was estimated. Five traits relating to fruit yield and quality were also assessed. The components of variance and genetic values were estimated by the REML/best linear unbiased prediction (BLUP) mixed model methodology. A difference in the severity of CABMV symptoms was recorded among the 119 genotypes evaluated. AUDPCM values varied from 750 to 1252.5 for individuals 202 and 161, respectively. Family 1 distinguished itself with the largest number of individuals selected for resistance; for agronomic traits, families 1 and 2 contributed most of the selected genotypes. Genotypes 167, 24, 34, 23 and 202 achieved the lowest AUDPCM values, being selected for most of the agronomic traits; these results indicate the potential of these genotypes to be chosen and recombined for the advancement of generations in breeding programs aimed at developing resistance to CABMV. The strategy of recombining resistant genotypes from RC1 populations appears to be promising for breeding for resistance to CABMV, of which the heritability is complex.