Quantitative Trait Loci (QTL) Underlying Biomass Yield and Plant Height in Switchgrass

Desalegn D Serba,E Charles Brummer,Guillaume Daverdin,Malay C Saha,Joseph H Bouton,Katrien M Devos

doi:10.1007/s12155-014-9523-8

Abstract

Switchgrass (Panicum virgatum L.) biomass yield and feedstock quality improvement are priority research areas for bioenergy feedstock development. Identification of quantitative trait loci (QTL) underlying these traits and of trait-linked markers for application in marker-assisted selection (MAS) is of paramount importance in facilitating switchgrass breeding. Detection of QTL for biomass yield and plant height was conducted on parental linkage maps constructed using a heterozygous pseudo-F1 population derived from a cross between lowland Alamo genotype AP13 and upland Summer genotype VS16. QTL analysis was performed with composite interval mapping. Four QTL for biomass yield and five QTL for plant height were identified using best linear unbiased predictors across ten and eight environments, respectively. The phenotypic variability explained (PVE) by QTL detected in the across environments analysis ranged from 4.9 to 12.4 % for biomass yield and 5.1 to 12.0 % for plant height. A total of 34 and 38 main effect QTL were detected for biomass yield and plant height, respectively, when data from each environment were analyzed separately. The PVE by individual environment QTL ranged from 3.3 to 15.3 % for biomass yield and from 4.3 to 17.4 % for plant height. In addition, 60 and 51 epistatic QTL were detected for biomass yield and plant height, respectively. Significant QTL by environment interactions were detected for QTL mapped in eight genomic regions for each of the two traits. Seven QTL affected both traits and may represent pleiotropic loci. Overall, 11 genomic regions were identified that were important in controlling biomass yield and/or plant height in switchgrass. The markers linked to the main effect and epistatic QTL may be used in MAS to maximize selection gain in switchgrass breeding, leading to a faster development of better biofuel cultivars.

Highlights

A renewable, low-carbon transportation fuel could mitigate global climate change that is exacerbated by the burning of fossil fuels [1] by supplementing oil supplies [2] and meeting increased energy demand resulting from global population growth and economic development [3]
Y×L and L×G interactions were significant for biomass yield, while Y×L, Y×G, L×G, and Y×L×G interactions were significant for plant height
The two parents differed considerably for biomass yield and plant height (Table 2), with AP13, a lowland genotype, being taller and higher yielding than VS16 which was selected from an upland ecotype

Summary

Introduction

A renewable, low-carbon transportation fuel could mitigate global climate change that is exacerbated by the burning of fossil fuels [1] by supplementing oil supplies [2] and meeting increased energy demand resulting from global population growth and economic development [3]. Sustainable nextgeneration (lignocellulose-based) feedstocks could supplement or replace current grain-based ethanol production [4] or could be directly burned to produce electricity. Switchgrass (Panicum virgatum L.) is a warm season C4 perennial grass native to the North American tall grass prairie [5] that has been identified as a promising feedstock for bioenergy production. Increased energy yield per unit area of switchgrass will improve its utility as a dedicated bioenergy crop [6]; biomass yield is an important trait in switchgrass breeding. Yield is a complex trait, the result of numerous mostly quantitatively inherited traits, and is greatly affected by the environment [7]

Methods

Results

Conclusion