QTL mapping of high digestibility trait in sorghum bicolor (L.) Moench

Abstract

As compared with other cereal grains, Sorghum bicolor shows very low levels ofprotein digestibility when exposed to proteolytic enzymes. Protein digestibility furtherdecreases when sorghum is cooked. It is speculated that low digestibility is the result ofextensive disulfide crosslinking in the - and -kafirins (storage proteins) surroundingthe endosperm protein bodies. The degree of crosslinking increases as sorghum iscooked, causing the highly digestible -kafirins found at the interior of protein bodies tobe locked within a tightly bound capsule, inaccessible to digestive enzymes. In thisresearch project, two major QTLs were found to be associated with proteindigestibility—one QTL unfavorably affecting digestibility and one QTL favorablyaffecting digestibility. By identifying the QTLs and the linked markers corresponding tothe highly digestible trait, breeders will be able to use marker-assisted selection toquickly and accurately identify highly digestible lines to advance in a breeding program.