QTL Mapping for Tillering Traits in Two Switchgrass Populations.

Switchgrass (Panicum virgatum L.) is a warm-season, tall-growing perennial grass native to North America. The species has great potential as a cellulosic feedstock crop for biofuel production. Plant tillering is an important morphological component contributing to switchgrass biomass yield. Information regarding heritability and QTLs of the trait and related morphologic traits is critical for breeding high yielding cultivars. Accordingly, the objectives of this study were to estimate broad-sense heritability for tillering and related traits, to analyze correlation between biomass yield and tillering traits, and to identify quantitative trait loci (QTL) for the traits. A selfed population of ‘NL94’ plant and a hybrid population between NL94 and SL93 plants were field established in a randomized complete block design with three replications in Stillwater and Perkins, OK. Phenotypic data were collected in two years at the two locations and genotypic data were obtained by genotyping simple sequence repeat (SSR) markers in the two populations. Plant base size, plant girth, tillering ability, tiller diameter and tiller dry weight were positively correlated with biomass yield in both populations. Twenty-eight and 23 QTLs were detected in the selfed population and hybrid population, respectively. The findings could be used in accelerating the breeding of new cultivars with improved tillering potential in conventional and marker-assisted selections.