Research Article Evaluation of resistance to Cowpea aphid-borne mosaic virus in passion fruit backcrosses for recurrent selection and development of resistant cultivars

Abstract

. The cultivation of passion fruit occupies an important place in Brazilian fruit culture; however, there have been successive declines in production. The main cause of this retraction in production is an increase in the incidence of Cowpea aphid-borne mosaic virus . This virus can cause severe deformation of the fruit and make passion fruit production inviable. Due to a lack of cultivars resistant to this virus, the Universidade Estadual do Norte Fluminense Darcy Ribeiro passion fruit breeding program has sought to develop resistant cultivars. The objective of this work was to evaluate the resistance to CABMV of a passion fruit second generation backcross (BC 2 ) segregating population via the REML/BLUP procedure aiming at selecting resistant genotypes with agronomic characteristics to start a recurrent selection program and possibly produce a new passion fruit cultivar. Virus resistance was measured by the average area under the disease progress curve using a score based on the average of each family. The BC 2 - 17 family showed the best additive genetic gain concerning resistance to CABMV and the worst for fruit production. The BC 2 - 293 family, had the highest estimated value of genetic gain for fruit production. The genetic variability found in the BC 2 segregating population allows us to select superior genotypes. Twenty-nine genotypes were selected to start the recurrent selection program aimed at resistance to CABMV. The - Two genotypes (BC 2 - 89 and BC 2 - 323) showed potential to be launched as CABMV resistant passion fruit cultivars. The genetic parameters were estimated by REML and the individual additive genetic effects by BLUP for the two characteristics evaluated (resistance to CABMV and FP). Data were analyzed using the Selegen REML/BLUP statistical software, model 147 (Resende, 2016). The analysis followed the statistical model y= Xr+Zg+Wp+e, where y is the vector of data, r is the vector of the replicate effects (assumed to be fixed) added to the overall mean, g is the vector of the genotypic effects individual (assumed to be random), p is the vector of plot effects (random), and e is the vector of errors or residuals (random). The capital letters represent the incidence matrices for the said effects. The following components of variance (REML) were estimated: σ 2 g : genotypic variance between full-sibs progenies, equivalent to 1/2 of the additive genetic variance plus 1/4 of the dominance genetic variance, ignoring epistasis; σ 2plot : environmental variance between plots; σ 2 within : residual variance within the plot; σ 2 f : individual phenotypic variance; h 2 a : individual narrow-sense heritability, obtained by ignoring the fraction (1/4) of the genetic dominance variance; h 2mp : mean heritability of progenies, assuming complete survival; h 2ad : additive heritability within the plot, obtained by ignoring the fraction (1/4) of the genetic variance of dominance; c 2plot : coefficient of determination of plot effects; Acprog: progeny selection accuracy, assuming complete survival; and General average.