Quantitative trait loci mapping of stem sugar content and stem diameter in sorghum recombinant inbred lines using...

Sweet sorghum is an important crop with sugary stem that can mainly be used for syrup, fodder and bio-fuel. Many sugar content QTLs have been discovered from different sources through breeding worldwide. Most of these QTLs are detected using exotic germplasm as a mapping population. This study aimed to detect and map QTLs for stem sugar content and stem diameter targeting Ethiopian recombinant inbred lines of sorghum using genotyping-by-sequencing.

Genotyping-by-sequencing and phenotyping using 139 recombinant inbred lines of sorghum as mapping populations were conducted. A total of 1082 polymorphic and high quality SNP markers that are evenly distributed across the ten linkage groups of sorghum were selected to detect and map the trait of interest. A genetic linkage map using 1082 SNP markers was constructed and several QTLs associated with stem sugar content and stem diameter were identified. Phenotypic variation explained by qBrix4-1 and qBrix2-1 ranged from 6.33 to 14%, respectively. Over two seasons, four QTLs for stem sugar content (qBrix1-1, qBrix2-1, qBrix4-1 and qBrix4-2) and three QTLs for stem diameter (qSD1-1, qSD8-1 and qSD9-1) were detected.

QTLs that significantly associated with stem sugar content and stem diameter have been detected and mapped. This will help sorghum breeding program to develop superior sweet sorghum varieties through the use of appropriate crop improvement approaches like marker assisted breeding. This ultimately contributes to the current development plan to considerably improve food, feed and bio-fuel supply in developing countries like Ethiopia.