Research Article Backcrossing in passion fruit: generation advance and selection of genotypes resistant to <i>Cowpea</i> <i>aphid-borne</i> <i>mosaic</i> <i>virus</i>

Abstract

The woodiness disease induced by the Cowpea aphidborne mosaic virus (CABMV) is regarded as a limiting factor for passion fruit production. We estimated genetic parameters for resistance and agronomic performance-related traits and selected genotypes resistant to CABMV in segregating populations of passion fruit. The experiment was a randomized-block design with four replicates, consisting of six full-sibling first backcross genotype families, in which 319 genotypes were evaluated. The disease symptoms were evaluated based on spontaneous occurrence of CABMV, using a scale of scores in young leaves, plant and fruits. Based on these scores, we estimated the area under the disease progress curve (MAUDPC). Agronomic traits were also assessed: fruit weight per plant and number of fruits per plant. The variance components and genetic value of each genotype were estimated for each variable via mixed models. The MAUDPC values ranged from 401.25 to 1192.5, indicating considerable genetic variability. The high individual narrow-sense heritability value for the MAUDPC trait (0.95) indicates the possibility of genotypic selection within CABMV-resistant families. For the production-related traits, even ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 20 (1): gmr18668 S.C. Preisigke et al. 2 with low heritability values, it was possible to obtain genetic gains in individual selection, which ranged from 4.99 to 6.24% for fruit weight and 22.64 to 28.70% for number of fruits. The genotypes chosen to compose the next backcross generation should be selected based on resistance to CABMV, which is the main objective of the program, since agronomic traits can be recovered from backcrosses. Of the 30 individuals ranked for CABMV tolerance, genotypes 501, 506, and 597 were selected to compose the next generation of backcrosses. These had the lowest values for MAUDPC.

Integrating the Classical and Molecular Approaches Toward Passion Fruit Resistance Against CABMV

“…This success might be attributed to the extensive evaluation of numerous genotypes and the high heritability coe cients for the trait in question. For traits governed by multiple genes, it is advisable to assess a wide array of genotypes in each backcross generation and conduct a thorough examination of the disease-induced symptoms, enhancing the precision of selecting genotypes resistant to the virus (Preisigke et al, 2021).…”