Hybrid Performance in Wheat as Related to Parental Diversity

Abstract

The probability of recovering a superior individual from the cross of two inbred parents is greater if both parents are similar in performance as opposed to one parent being inferior. Heterosis, coefficients of parentage, and molecular markers have been advocated to assess genetic diversity directly between parents. This study was done to determine the extent of DNA polymorphisms among a set of seven hard red spring wheats and the relationship between genetic diversity based on these molecular markers and coefficients of parentage, and to examine the relationship between diversity and hybrid performance in a diallel cross of these parents. Parents plus the F1 hybrids were grown in three environments. Grain yield, kernel weight, and protein concentration were measured. Coefficients of parentage, r, were computed for all pairwise combinations of parents. Parents were assayed with 63 sequence tagged site (STS) polymerase chain reaction (PCR) primer sets. Genetic similarities, GS, were computed using 27 STS PCR primer sets that showed polymorphisms. Rank correlations were computed between the 1 ‐ r and 1 ‐ GS measures of genetic diversity and F1 performance, mid‐parent beterosis, and SCA effects. The only significant associations between diversity and hybrid performance were those between 1 ‐ r and kernel weight SCA effects and beterosis, and protein concentration heterosis. Genetic diversity was inversely related to heterosis and SCA effects for protein concentration. Correlations between the 1 ‐ r and 1 ‐ GS measures of diversity and hybrid performance traits were of the same sign and about equal in magnitude. Coefficient of parentage and GS were significantly correlated, and cluster analysis based on the 1 ‐ r and 1 ‐ GS measures of diversity grouped the genotypes similarly. Neither diversity measure showed promise for predicting F1 performance, but both measures provided similar information for grouping and differentiating genotypes.