Vol. 78 No: 6

Title:
Performance of hybrid segregating populations of pepino (Solanum muricatum) and its relation to genetic distance among parents

Authors:
A. RODRÍGUEZ-BURRUEZO, J. PROHENS and F. NUEZ

pp: 911-918

Abstract:
The success of pepino (Solanum muricatum), a vegetatively propagated crop, as an alternative for vegetable crop diversification requires the development of new cultivars that combine both high yield and good fruit quality. Four unrelated clones, complementary for yield (Sm-23), tomato mosaic virus resistance (Sm-4 and Sm-26) or fruit quality (Sm-4, Sm-26 and Sm-29), were crossed in all combinations (except selfings and Sm-4 × Sm-26) to produce five segregating hybrid populations. AFLP analysis of parental clones with four combinations of primers revealed 187 polymorphic bands out of 438 scored (42.7%). Genetic distance among parents varied between 0.325 (Sm-4 and Sm-23) and 0.210 (Sm-29 and Sm-26). For all traits studied (yield, fruit weight and soluble solids content), hybrid populations means ranged between those of the highest and lowest of the four parental clones. However, transgressive individuals for all traits could be found in almost all hybrid populations, and the mean of the 25% best individuals was higher than the best of the four parental clones (Sm-23 for yield and fruit weight, with 5.89 kg m^-2 and 412.9 g, respectively, and Sm-26 for soluble solids content with 8.92 8Brix) in two hybrid populations for yield and fruit weight and in all hybrid populations for soluble solids. Heritabilities for all the traits studied and hybrid populations ranged between 0.45 and 0.62, except for yield in Sm-23 × Sm-29 and fruit weight for Sm-23 × Sm-26, in which values were not significantly different from zero. Estimates of genetic advance show that prospects for selecting new improved clones superior to the parentals used can be met by using complementary crosses. No significant correlation of the mid-parent value with hybrid population means was found. However, a highly significant correlation (>0.90) was found for genetic distance with the mean yield of hybrid populations and the 25% best individuals, but not for the other traits. Genetic distance based on neutral molecular markers could be used for predicting the yield of pepino segregant hybrid populations, and therefore may be of great value for choosing parents. This work shows how conventional breeding combined with tools derived from new biotechnologies can have a synergistic effect on pepino breeding.

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