Evaluation of resistance to Cowpea aphid-borne mosaic virus in passion fruit backcrosses for recurrent selection and development of resistant cultivars
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 (BC2) 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 scale, evaluating the percentage of symptoms in the plant and young leaves. The total fruit mass produced per plant was used to assess fruit production. Based on this information, the components of variance and genetic value were estimated via REML/BLUP. The highest values estimated for genetic parameters, for the two characteristics evaluated, were based on the average of each family. The BC2 - 17 family showed the best additive genetic gain concerning resistance to CABMV and the worst for fruit production. The BC2 - 293 family, had the highest estimated value of genetic gain for fruit production. The genetic variability found in the BC2 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 (BC2 - 89 and BC2 - 323) showed potential to be launched as CABMV resistant passion fruit cultivars.