Genomics of Quality Traits

Abstract

This chapter reviews what is known about genes that control the timing of flowering during the year or inflorescence development in the Triticeae, focusing on barley and wheat. The methods used to identify major genes controlling flowering in response to extended periods of low temperature (Vernalization; Vrn genes) or day length (Photoperiod; Ppd genes) and genes controlling inflorescence development are considered. This shows that direct candidate gene approaches have proved less effective than positional cloning or composite fine mapping/candidate gene methods. The implications for identi- fying new target genes are discussed. The analysis of genetic pathways identified in models is also considered as an aid to understanding how genes in the Triticeae affect phenotypic variation. Finally, the evolution of these traits under domestication is considered in relation to the finding that orthologous genes and similar mutations are found to be major contributors to adaptive variation in different species.