Prediction of Heterosis in Crop Plants – Status and Prospects

Abstract

Heterosis has been commercially exploited in many crops; however, its genetic and molecular basis is still not clear. The availability of advanced genomic tools has encouraged several research groups to dissect heterosis into genetic components. Prediction of heterosis using molecular markers is the first step towards this direction, as it may lead to the identification of markers and genomic regions associated with heterosis. Practically, it increases the efficiency of hybrid breeding by marker-assisted selection of superior parental combinations without large-scale field evaluation. Extensive studies in important crops like rice, wheat and maize have identified the genes / genomic regions associated with heterosis and also demonstrated the potential of molecular prediction. Recent trends in whole transcriptome and metabolome analyses will help in the identification of genes or metabolic networks involved in the expression of heterosis. Various genomic tools such as heterotic loci, molecular markers associated with heterotic gene blocks, ESTs and heterosis-related gene databases provide better opportunities for understanding the molecular basis of heterosis and to develop reliable methodologies for a realistic prediction of heterosis. This review provides critical analysis of the prediction of heterosis in crop plants and its implications in hybrid development.