Molecular Mechanisms and the Laws of Homologous Variation

Vavilov’s Law of Homologous Series in Variation is built upon the concept that similar traits selected during domestication would share a common genetic basis. There is predictive value in understanding these traits because of likely shared mechanisms.   Modern genomics tools can be implemented to test this concept.  Important plant traits such as flowering , disease resistance and abiotic stress tolerance share remarkably similar mechanisms and support Vavilov’s contention.  On the other hand, some traits do not obey this principle.  For instance, seed shattering was domesticated multiple independent times in parallel.  In these cases, molecular resolution shows that the different domestication events were based on separate molecular mechanisms.  In a broader view, colinearity and synteny are conserved within the genes underlying these functions.  An analysis of larger genome structure is consistent with Vavilov’s Law, whereas selection of specific traits frequently can be attributed to gene-level alterations that fit into the existing syntenic relationships.

Directed breeders, to the continued improvement and economic development of plants for humanity. Inherent genetic plant variability is the basis of domestication and breeding into crops of economic importance with food, fuel, fiber, and industrial uses. The objective of this manuscript is to summarize Vavilov’s revised centers of origin of cultivated crops and discuss how these have been further modified by other scientists including, most notably, Jack Harlan.  Examples of major crop species, including cereals, protein plants, starch crops, fruits, and vegetables, will be discussed in relation to their origins. Conservation of their genetic resources and potential for future development will be presented.