Heterotic analysis using AFLP markers reveals moderate correlations between specific combining ability and genetic distance in maize inbred lines

Abstract

Heterotic breeding strategies in maize (Zea mays L.) can be improved if high specific combining abilities in hybrid performance and a DNA marker-based genetic distance in the inbred lines is correlated, and hence heterosis can reliably be predicted. In this study, the genetic diversity across 9 elite maize inbred lines was evaluated using the amplified fragment length polymorphism (AFLP) marker. The genetic distance (GD) between each of all possible inbred pairs and the specific combining ability (SCA) and heterosis in the F1 hybrids were evaluated in a diallel set of crosses (Griffing II). Nineteen AFLP primers produced 1019 reproducible bands of which 691 (67.81%) were polymorphic. This gave an average of 53.6 bands per primer combination. A matrix of Genetic similarity (GS) according to UPGMA clustered the inbred lines into 4 groups with a GD ranging from 0.2442 to 0.4093. The results indicated that GD was moderately correlated with grain yield (0.4096), mid-parent heterosis (MH) (0.3624), better-parent heterosis (BH) (0.3309) and SCA (0.4725). Although the AFLP markers have high polymorphisms and can be used to detect the genetic divergences, place maize inbred lines in different heterotic pools and identify the most positive SCAs and heterosis, they are still limited in fully predicting hybrid performance.