Genetic diversity between papaya lines and their correlation with heterosis in hybrids for disease resistance and morpho-agronomic traits

Silvaldo Felipe da Silveira,Helaine Christine Cancela Ramos,Deisy Lucia Cardoso,Ramon de Moraes,Marcelo Vivas,Pedro Henrique Dias dos Santos,Messias Gonzaga Pereira

doi:10.1590/0100-5405/176828

Silvaldo Felipe da Silveira, Helaine Christine Cancela Ramos + Show 5 more

Open Access

https://doi.org/10.1590/0100-5405/176828

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Abstract

ABSTRACT This study aimed to verify if the genetic divergence between papaya lines, obtained by means of molecular markers, is correlated with heterosis in the hybrids for characteristics related to production, fruit quality and disease resistance. Eight parents and 56 hybrids obtained from diallel crosses were evaluated in randomized blocks, with four replicates. The number of commercial fruits (NCF), the average fruit weight (AFW), the productivity (PROD), the fruit firmness (FIRM) and the total soluble solids (TSS) were evaluated, as well as the severity of black spot on leaves (BSS) and fruits (BSSFr), phoma spot (PSS) and powdery mildew on leaves (PMS). Correlations were estimated between genetic divergence, obtained based on SSR, and heterosis, estimated for each characteristic in four possibilities of crossings within the diallel: i) all crossings; ii) between parents of the ‘Solo’ group; iii) between parents of the ‘Formosa’ group; and iv) between parents of ‘Solo’ with ‘Formosa’ group and ‘Formosa’ with ‘Solo’ group. Results indicate the possibility of exploring heterosis both in crossings between groups and in crossings within groups. The low magnitude of the estimates of correlation between heterosis and morphological characteristics of the hybrids with genetic distance obtained by SSR in the parents indicates that the behavior of hybrids cannot be inferred based on the genetic divergence between parents.

Highlights

N SSR, and heterosis, estimated for each characteristic in four possibilities of crossings within the diallel: i) all crossings; ii) between parents of the ‘Solo’ group; iii) between parents of the ‘Formosa’ group; and iv) between parents of ‘Solo’ with ‘Formosa’ group and ‘Formosa’ with ‘Solo’ group
The low magnitude of the estimates of correlation between heterosis and morphological characteristics of the hybrids with genetic distance obtained by SSR in the parents indicates that the behavior of hybrids cannot be inferred based on the genetic divergence between parents
Studies with lineages obtained from the populations BR-105 and BR-106, correlating productivity and genetic divergence estimated through molecular markers such as RFLP, RAPD, microsatellites and AFLP, showed that the best markers to allocate the

Summary

Introduction

N SSR, and heterosis, estimated for each characteristic in four possibilities of crossings within the diallel: i) all crossings; ii) between parents of the ‘Solo’ group; iii) between parents of the ‘Formosa’ group; and iv) between parents of ‘Solo’ with ‘Formosa’ group and ‘Formosa’ with ‘Solo’ group. Falconer [9] suggests that, at any degree of dominance above zero, heterosis is a function of allele frequency between the parents; there is a positive correlation between genetic divergence and heterosis For this reason, lineage diversity estimates can be used as a predicting tool of superior crosses in plant breeding programs [14]. Gadheri et al [10] reported that dominance or epistasis effects involving dominance are required to have a positive association between genetic divergence and heterosis and that the parents have differences in allele frequencies that control the trait under study This difference should increase with the parent’s divergence, allowing the dominance effects to manifest and, increase the heterosis phenomenon

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Results