Quantitative Trait Locus Analyses of the Domestication Syndrome and Domestication Process

Domestication of many of today’s main food crops occurred approximately 10,000 years ago with the beginning of agriculture. It has lead to the selection by farmers of a wide range of morphological and physiological traits that distinguish domesticated crops from their wild ancestors. These characteristics are collectively referred to as the domestication syndrome and include changes in plant architecture (e.g., apical dominance in maize), gigantism in the consumed portion of the plant (e.g., fruit size in tomato and eggplant), and reduced seed dispersal (i.e., nonshattering or nondehiscence, as in the common bean, sunflower, and cereals). Many investigations based on multidisciplinary approaches—such as genetic, archaeological, and phytogeographical analyses—have succeeded in identifying progenitor species and centers of domestication. However, the genetic and molecular bases of morphological evolution in plants under domestication are largely unknown. Advances in genome mapping, which have resulted in high-density molecular-marker linkage maps in most crops, have provided tools for dissecting the genetic basis underlying complex traits into their individual components, i.e., their quantitative trait locus (QTL). This method relies on the frequent ability to cross the crop and its wild progenitor. It enables the characterization of genetic differences in terms of the number and chromosomal location of the genes as well as quantitative estimates of the kind and amount of genetic effects associated with individual loci. Recent studies have analyzed the genetics of the domestication syndrome of crops belonging to diverse families. GENETIC BASIS AND ORGANIZATION OF THE DOMESTICATION SYNDROME