Research Article Characterization of a segregating population of passion fruit with resistance to <i>Cowpea</i> <i>aphid-borne</i> <i>mosaic</i> <i>virus</i> through morpho-agronomic descriptors

Abstract

In passion-fruit breeding programs, characterizing genotypes developed through morpho-agronomic descriptors helps quantify genetic diversity and identify individuals with desirable qualities. We examined the discriminatory ability of passion-fruit descriptors and determined their relative importance in the characterization of 91 genotypes from a breeding program for resistance to Cowpea aphid-borne mosaic virus. Twenty-four quantitative and 14 multi-category qualitative descriptors related to plant, leaf, flower, and fruit characteristics were used. The quantitative descriptors were subjected to correlation and principalcomponent analyses and selected based on direct selection and the Singh method. The traits were used to obtain a distance matrix, based on Gower's algorithm, and a comparative clustering between the dendrograms for the morpho-agronomic variables was obtained using the unweighted pair group method with arithmetic mean procedure. Based on the principal components method, the traits that most contributed to genetic variability were number of seeds (23.241%), petiole length (19.438%), and petal width (10.440%). In its turn by the Singh method, the traits androgynophore length (6.68%), ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 18 (2): gmr18255 V.O. dos Santos et al. 2followed by flower length (5.47%), area under the disease progress curve (5.27%), and peduncle length (5.17%) were those which most contributed to the differentiation of genotypes. Although seven descriptors (leaf length, bract width, corona long filament length, sepal length, fruit width, fruit mass, and mass of fruit pulp) showed little contribution to the characterization of genotypes, their discard is not suggested, as they significantly contribute to the discrimination of genetic divergence in the population. Comparative analysis between the dendrogram containing all descriptors and the dendrogram containing only flower, leaf, or fruit descriptors evidenced the need for using a large number of descriptors in the characterization of genetic diversity in Passiflora. The use of all 38 descriptors increased the efficiency in the discrimination of groups.

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>

“…These obtained the lowest genetic values for MAUDPC. Santos et al (2019 b) assessed the same hybrids obtained in this study based on morpho-agronomic descriptors and resistance to CABMV and selected genotype 501 as one of the most promising for the second backcross cycle, similar our findings. Although resistance is a trait of quantitative inheritance, backcrossing was effective in transferring resistance genes to CABMV, which may be due to the high heritability estimates for this trait and the large number of genotypes assessed.…”

Categories of variables in analysis of genetic diversity in S1 progenies of Psidium guajava

“…Therefore, there is no possibility of indicating minimum descriptors for the culture given the results found. Similarly, by using the Dendextend package when comparing the dendrograms, with all the descriptors and the dendrogram containing only flower, leaf, or fruit descriptors, Santos et al 33 made it clear that different descriptors are required to characterize genetic diversity in Passiflora, because both the number of clusters and the arrangement between genotypes did not remain the same.…”

Field assessment of a second generation backcross (BC1 × Passiflora edulis) of passion fruit for agronomic performance and resistance to CABMV

“…However, only their association with resistance will assure that the cultivar will remain in the market for a long time. The reaction of genotypes to viral infection depends on their genetic resistance (Freitas et al., 2016; Gonçalves et al., 2018; Santos et al., 2019), local management of the disease (Spadotti et al., 2019), hormone synthesis (Carr et al., 2018) and the interaction with vectors through volatile organic compounds, which can either attract or repel vector insect (Carr et al., 2020; Guo et al., 2019). These factors act together for the occurrence or suppression of viral infection.…”

“…At the molecular level, some studies have been published involving the identification of at least seven quantitative trait loci (QTLs) with small effects associated with resistance to the virus (Santos et al, 2019) and the characterization of the Passiflora × CABMV interaction using proteomics of P. setacea (resistant), P. edulis (susceptible) and their hybrids (Carvalho et al., 2019). However, the lack of markers associated with CABMV resistance genes prevents its widespread use, because this process is not easy since it depends on phenotypic evaluations for the selection of the individuals most resistant to CABMV disease.…”