Multivariate analysis to determine the genetic distance among backcross papaya (Carica papaya) progenies

Abstract

ABSTRACT. Morpho-agronomic and molecular (RAPD and ISSR markers) data were used to evaluate genetic distances between papaya backcross progenies in order to help identify agronomically superior genotypes. Thirty-two papaya progenies were evaluated based on 15 morpho-agronomic characteristics, 20 ISSR and 19 RAPD primers. Manhattan, Jaccard and Gower distances were used to estimate differences based on continuous and binary data and combined analyses, respectively. Except for production, there were significant differences in the continuous variables among the genotypes. The molecular analysis revealed 193 dominant markers (ISSR and RAPD), being 53 polymorphic loci. Among the various clusters that were generated, the one based on a combined analysis of morpho-agronomic and molecular data gave the highest cophenetic correlation (0.72) compared to individual Multivariate analysis to estimate divergence in papaya analysis, consistently allocating the progenies into six groups. We found that the Gower algorithm was more coherent in the discrimination of the genotypes, demonstrating that a combination of molecular and agronomic data is valuable for studies of genetic dissimilarity in papaya.

Use of morpho-agronomic traits and DNA profiling for classification of genetic diversity in papaya

“…This finding indicates that the genetic distance according to molecular markers was not precisely representative of the genetic distance based on quantita tive characters. Ramos et al (2012) found a similar situation when analyzing several progeny from backcrosses in which the cluster analysis based on morpho-agronomic and molecular data showed the same number of groups, but their profiles were considerably different, which can be confirmed by the low value found for the correlation between the two matrices.…”

“…However, molecular markers may not correlate with the phenotypic expression of a genomic trait, which can be demonstrated by the low correlation between the Qut data and molecular markers, where correlations were 0.09 and 0.26 for AFLP and ISSR, respectively (Table 4). In addition, the separate analyses of morpho-agronomic and molecular data can result in fragmented and often inaccurate inferences, making it difficult to understand the genetic relationships between the relevant germplasms (Ramos et al, 2012). In general, the matrix of dissimilarities and the dendrogram generated based on the average of morphoagronomic and molecular data present a more balanced view of the genetic variability found in inbred lines, varieties, cultivars, and papaya hybrids.…”

“…According to Ramos et al (2012), the traits related to fruit size (average weight, length, and diameter), as well as plant vigor and low fruit firmness, clearly contributed to the distinctiveness of 26 papaya progeny, allocating the fruits to seven main groups. In the present study, the fruit traits demonstrated high significance for classifying the genotypes, as did other plant traits, such as height, vigor, and flowering.…”

“…In C. papaya, there have been few reports concerning the use of ISSR markers. However, ISSR has been used to evaluate genetic distances between papaya backcross progeny (Ramos et al, 2012). Twenty ISSR primers generated 98 bands, 18 of which were polymorphic (18.36%).…”

Combining ability of recombinant lines of papaya from backcrossing for sexual conversion

“…Foram utilizados 66 genótipos de mamoeiro sendo, 22 linhagens derivadas do 'Cariflora' convertido para hermafrodita, 20 híbridos oriundos do cruzamento com o testador 1 ('JS-12' -híbridos T 1 ) e 22 híbridos do testador 2 ('SS-72/12' -híbridos T 2 ), além de duas testemunhas comerciais, a cultivar 'Golden' e o híbrido 'Tainung'. (RAMOS et al, 2011(RAMOS et al, , 2012(RAMOS et al, , 2014SILVA et al, 2007). Tais linhagens são oriundas de diferentes gerações de retrocruzamento, possuem diferentes níveis de endogamia e apresentam um acréscimo na variabilidade genética disponível para a cultura.…”