Mapping of QTLs Associated with °Brix and Biomass-Related Traits in Sorghum Using SSR Markers

Abstract

The non-renewability and greenhouse gas emission nature of crude oil led to the use of renewable plant-based biofuels as alternative energy. Sweet sorghum offers one of the best plant-based bioethanol production from its sugary stalk. Identification and mapping of quantitative trait loci associated with sugar-related traits in sorghum is a crucial step toward the improvement of the sugar content of the crop. The present study was carried out to identify and map QTLs associated with °Brix, stalk diameter and plant height using F2:3 segregating mapping populations derived from a cross between grain sorghum (Sorcoll 163) and sweet sorghum (Gambella). Phenotypic evaluation was conducted in two different environments. A genetic map was constructed using 192 F2 populations genotyped using 76 SSR markers. Estimated heritability for °Brix, stem diameter and plant height amounted to 0.88, 0.41 and 0.65, respectively. A total of seven QTLs distributed across five linkage groups that controls °Brix content were detected using Inclusive Composite Interval Mapping. Each QTL contributed 17.2–44.3% of the total phenotypic variation. The two QTLs located on linkage group SBI-05 and SBI-06 repeated in both environments. These QTLs can be the target of the breeding programs in the future due to high heritability as well as stability in two different environments. The number of SSR markers used in present study is relatively fewer and fine mapping of the target regions should be considered in order to further dissecting the region. All the detected QTLs in this study are categorized as major QTLs, and it could be used further in sweet sorghum improvement program.