Excessive water stress can cause severe damage to sorghum and results in significant yield reduction. The aim of this study is to identify quantitative trait loci (QTL) for excessive water stress in sorghum. As a first step, two out of 21 bmr mutants were selected for their superior agronomic performance and Chlorophyll a fluorescence OJIP transient, and were crossed with an elite Korean cultivar, Hwangkeumchal, to construct mapping populations. One hundred ten out of 236 SSR primers showed polymorphism between two parens, which cover ten chromosomes of sorghum from different published SSR linkage maps of sorghum. Development of recombinant inbred lines from the crosses ‘25M2-0698 x Hwangkeumchal’ and ‘25M2-0404 x Hwangkeumchal’ are in progress using the single seed descendent method for generation acceleration.

Grain sorghum is the fifth most important crop grown in the world for either a major food crop or animal feed. It is important to identify the genetic diversity of sorghum genetic resources for cultivar development and evaluation of sorghum accessions in Korea. Two hundred thirty six SSR primer sets, which are evely distributed across the sorghum genome, were used to assess the genetic variation of 23 sorghum accessions with a US cultivar, BTx623. Results showed that SSR markers were highly polymorphic among the sorghum collections and the average alleles per locus were 3.15 with the average of 0.436 PIC (polymorphism information content) values. The sorghum accessions in this study were unequally separated and were clustered into 4 groups. The results showed that there was a sufficient SSR polymorphism with SSR primers used among Korean sorghum accessions, and the development of genetic map and marker-assisted selection for cultivated sorghum would be feasible with further studies.