Progress in Breeding for Perenniality in Sorghum

Perennial crops may provide consistent food and biomass supplies while preserving ecological capital and reducing water and energy inputs. Sorghum, one of the few multi-purpose crops that provide both grain and biomass in some of the world’s most adverse conditions, has two perennial relatives as well as rich morphological diversity occurring during divergent evolution both in the wild and under domestication, making it a good candidate for breeding for perenniality. Crosses between cultivated and wild perennial sorghums will offer new opportunities to reveal genetic basis of traits related to perenniality. We describe F2 and F2:3 populations derived from an elite cultivar of S. bicolor, and S. halepense, which have displayed tremendous phenotypic variations, including varying degrees of rhizomatousness, winter and spring regrowth, and second-season “ratooning” within a single growing season. An initial assay of 100 SSR markers has detected some QTLs responsible for rhizomatousness and overwintering in this population, and permits comparison to QTLs found in a diploid population derived from annual S. bicolor x perennial S. propinquum (the progenitors of S. halepense). Clarifying the genetic control of phenotypic variations in this unusual population and its progenitors will strengthen our understanding of the evolution of perenniality, and also shed new light on prospects for breeding perennial crops optimized for food and/or biomass production.