QTL Mapping of Biomass Related Traits in Sweet Sorghum

Sweet sorghum is an efficient feedstock for ethanol production. It has high tolerance to drought and produces a lot of carbohydrates stored in its stalk using minimum water and fertilizer. To be an alternative sustainable energy crop, sweet sorghum should be developed for an efficient multipurpose crop. In this study, quantitative trait loci (QTL) for the main components of sweet sorghum and grain sorghum productivity; anthesis date, plant height, biomass yield, stem diameter, brix, 100 seed weight, and grain yield were detected using 198 F7 recombinant inbred lines (RILs) derived from a cross between Wray (sweet sorghum) and Macia (grain sorghum). The RILs and their parents were grown under four different environments and were genotyped-by-sequencing (GBS). FASTQ files (raw sequences) were analyzed using TASSEL4 GBS pipeline and using Bowtie2 as the aligner. GBS provided 914 potential SNPs. QTL IciMapping was used for QTL analysis using inclusive composite interval mapping of additive (and dominant) QTL (ICIM-ADD). Major QTLs were detected for anthesis date on chromosome 7 with 30.0% of the phenotypic variance (PVE), plant height and biomass yield on chromosome 9 with 31.2% and 23.7% PVE respectively, stem diameter on chromosome 3 with 15.1% PVE, brix and grain yield on chromosome 4 with 12.7% and 34.6% PVE respectively, and 100 seed weight on chromosome 1 with 19.4% PVE. The detected QTLs could help in searching for the genes of bioenergy related traits and could be used for development of molecular markers to select individuals within a breeding population on the basis of these markers.