Genetic Mechanism of Switchgrass Heading and Flowering Time.

Switchgrass is a native prairie grass that has shown implications in being a valuable bio-energy crop. Switchgrass is capable of surviving a variety of environments, yielding large amounts of biomass, has high water use efficiency, and requires relatively low amounts of inputs, which makes it a primary candidate for biofuel production. The physiological change from juvenile to reproductive adult can draw important resources away from growth and into producing reproductive structures, thus limiting the growth potential of early flowering switchgrass plants. Delaying the flowering of switchgrass by four to five weeks could increase the total biomass by 30-50%. To develop a rational strategy for creating improved switchgrass with late flowering, it would be beneficial to have a better understanding of the genetic mechanisms that control flowering time in switchgrass. The goal of this project is to identify genetic variation of heading date and flowering time in three related switchgrass populations. The three populations are reciprocal crosses. Data of heading date and flowering time were collected from three small segregating populations (total ~230 individuals) derived from lowland (late flowering) and upland (early flowering) ecotypes in two locations, Lafayette, IN (hardiness zone 5) and Dekalb, IL (hardiness zone 6). In 2015, the heading date and flowering time of the three segregating populations ranged from 177 to 252 and 185 to 271 days across both locations. The interaction of genotype by environment was explored to determine if location affected the heading and flowering dates. Large amount of single nucleotide polymorphisms were obtained by exome sequencing. Further, genome wide association study is being conducted to identify genetic variants related to heading and flowering within the populations. Identifying genetic variants related to flowering could assist in developing late flowering varieties of switchgrass with high biomass yield.