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Influence of the brown midrib 6 and 12 genes on forage and grain sorghum plant characteristics and predicted animal responses

Amanda L Oliver, University of Nebraska - Lincoln


Lignin provides structural support to plants. While being beneficial to the plant, lignin hinders the digestibility of forages by ruminant animals. Chemical and genetic approaches have been used to alter the lignin content of forages allowing for greater digestibility of forages. Brown midrib mutants (bmr) have decreased lignin content, however a decrease in plant vigor is often associated with the mutations. The bmr phenotype is caused by alterations in the pathway of lignin biosynthesis. Three different mutations have been identified in sorghum; bmr-6, 12, and 18 with apparent utility. These mutations differ by where in the pathway modification occurs. An experiment was conducted to examine the effects of the bmr genes on the digestibility of forage sorghum fed to lactating dairy cattle. Dairy cattle fed the bmr mutant sorghum had increased milk production when compared to the conventional sorghum silage. To determine if one bmr mutation (bmr-6) is superior to another (bmr-12), lines of forage sorghum, grain sorghum, and a grain hybrid near-isogenic for these genes were developed. These lines were grown and harvested for two consecutive years at two separate locations. Chemical analysis and field yields were ascertained. The bmr-12 genotype was generally superior to the bmr-6 as well as the wild-type. Both bmr genotypes had decreased lignin and increased digestibility when compared to the wildtypes. Therefore, bmr mutations improve the digestibility of forage sorghums and the residue of grain sorghum, and significant differences exist between the bmr-6 and -12 mutants. ^

Subject Area

Agriculture, Agronomy|Agriculture, Animal Culture and Nutrition

Recommended Citation

Oliver, Amanda L, "Influence of the brown midrib 6 and 12 genes on forage and grain sorghum plant characteristics and predicted animal responses" (2004). ETD collection for University of Nebraska - Lincoln. AAI3142093.