Quantitative Genetic Analysis of Wood Chemistry and Biomass Traits in Sunflower

Cultivated sunflower (Helianthus annuus L.) is grown worldwide as an oilseed crop, however, evidence suggests that sunflower can also be used as a dual use crop and harvested as a source of lignocellulosic biomass. To gain a better understanding of the genetics of wood chemistry and biomass related traits in sunflower a H. annuus x (H. annuus x H. argophyllus) BC₁ population (n=525) and a H. annuus (elite x landrace) recombinant inbred line population (RIL) (n=169) were evaluated in multiple locations [(BC₁ – Athens, GA; Ames, IA; Vancouver, BC), (RIL – Athens, GA)] in 2009. Stem sections were analyzed using a pyrolysis Molecular Beam Mass Spectrometer (pyMBMS) and biomass related traits (e.g. days to flower, plant height, total and/or main stem biomass, stem diameter and basic specific gravity) were phenotyped. The BC₁ population was genotyped with a 384 BeadXpress SNP array and the RIL population was genotyped with a 10,640 SNP Infinium Chip (both from Illumina). Genetic maps each with 17 LGs were created; the H. annuus x H. argophyllus BC₁ map was 1942 cM/285 loci and the H. annuus (elite x landrace) RIL map was 1407 cM/3117 loci. Novel QTL for plant biomass and stem density were identified using CIM. QTL for S- and G-lignin were clustered on LGs 5, 16, 17 and QTL for carbohydrate content (celluloses, hemicelluloses) were clustered on LG7. QTL for ratios of cellulose/lignin, S/G lignin and hemicellulose/cellulose were clustered at the bottom of LG17. Most QTL were small (PVE <15%) or medium effect (PVE = 15-25%).