Qtl Mapping for Reproductive Maturity in Lowland Switchgrass Populations

Abstract

Switchgrass (Panicum virgatum L.) has high potential to be a major cellulosic bioenergy crop. Selection for later flowering plants will extend the growing season, likely resulting in larger biomass yields. However, it is little known of the genetic structure and mechanism for reproductive maturity in switchgrass. Accordingly, the major objective of this study was to identify genomic regions for reproductive development. Two lowland switchgrass populations, a hybrid population consisting of 176 progeny derived from a cross between parents NL94 (♀) � SL93 (♂) and a first-generation self-fertilized population of 265 progeny from NL94, were used in this study. Significant genetic variation for reproductive maturity stages was observed within each of the two populations. A total of 178 simple sequence repeat (SSR) markers were genotyped in the hybrid population for the construction of a linkage map while a pre-existing linkage map of 439 SSR markers was used for quantitative trait loci (QTL) analysis between markers and phenotypic data. QTL analysis revealed that reproductive maturity was a complex trait as controlled by multiple genomic regions. The QTL regions between PVGA-1727/1728 and PVGA-1201/1202 on linkage group (LG) 3b, between nfsg-125 and PVE-781/782 on LG 2b, and between PVCAG-2503/2504 and PVAAG-3253/3254 on LG 7a were identified to be associated with reproductive maturity in both populations. Broad sense heritabilities were 0.08 to 0.66 and 0.03 to 0.48 for the selfed and hybrid populations, respectively. Use of the markers linked to the significant QTLs in the populations could accelerate the development of switchgrass varieties having later flowering time as a means in increasing biomass yield in switchgrass.