The dominance model for heterosis explains culm length genetics in a hybrid sorghum variety

Abstract

AbstractHeterosis helps increase the biomass of many crops; however, while models for its mechanisms have been proposed, it is not yet fully understood. Here, we use a QTL analysis of the progeny of a high-biomass sorghum F1hybrid to examine heterosis. Five QTLs were identified for culm length and were explained using the dominance model. Five resultant homozygous dominant alleles were used to develop pyramided lines, which produced biomasses like the original F1line. Cloning of one of the uncharacterised genes (Dw7a) revealed that it encoded a MYB transcription factor, that was not yet proactively used in modern breeding, suggesting that combining classicdw1ordw3, and new (dw7a) genes is an important breeding strategy. In conclusion, heterosis is explained in this situation by the dominance model and a combination of genes that balance the shortness and early flowering of the parents, to produce F1seed yields.