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United States Department of Agriculture

Agricultural Research Service

Title: Comparitive Effects of the Sorghum Bmr-6 and Bmr-12 Genes Ii: Grain Sorghum, Grain Yield, Stover Yield, and Stove Quality.

Authors
item Oliver, Amanda - OKLAHOMA STATE UNI
item Pedersen, Jeffrey
item Grant, Rick - W.H. MINER INSTITUTE
item Klopfenstein, Terry - UNI OF NE
item Jose, Doug - UNI OF NE

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 7, 2005
Publication Date: September 23, 2005
Citation: Oliver, A., Pedersen, J.F., Grant, R., Klopfenstein, T., Jose, D. 2005. Comparitive effects of the sorghum bmr-6 and bmr-12 genes ii: grain sorghum, grain yield, stover yield, and stove quality.. Crop Sci. 45:2240-2245.

Interpretive Summary: Over 7 million acres of grain sorghum are harvested annually in the United States each year, with the residue being primarily utilized for grazing. It may be possible to add value to the total system by increasing the digestibility of that residue by the use of brown midrib (bmr) genes, which reduce lignin content, if grain yields can be maintained. There are several such bmr genes in use with disagreement, but little data available about their relative value. The objectives of this study were to evaluate the effect of two genes, bmr-6 and bmr-12, which reduce the activity of two different enzymes involved in lignin synthesis, on grain yield and residue yield and quality in six grain sorghum lines and a hybrid. The bmr genes reduced grain yield and residue yield in the lines, however yield reduction was not observed in the bmr-12 version of the hybrid. The bmr-12 near-isolines generally had lowest stover lignin content and highest fiber digestibility, bmr-6 was intermediate, and normal counterparts had highest lignin content and lowest fiber digestibility. When all data are considered, the bmr-12 gene appears superior to the bmr-6 gene in terms of potentially adding value to grain sorghum for use in crop/animal systems. The variable expression of bmr-12 and bmr-6 in different lines indicates that testing the genes in individual hybrids is critical in determining the realized impact on value.

Technical Abstract: Nearly 3 million hectares of grain sorghum [Sorghum bicolor (L). Moench] are harvested in the United States each year. It may be possible to add value to crop/animal systems by enhancing the digestibility of the stover residue by the use of brown midrib (bmr) genes if grain yields can be maintained. The objectives of this study were to evaluate the effect of bmr-6 and bmr-12 genes on grain yield of sorghum, and to evaluate the effect of the bmr genes on stover yield and quality in near-isogenic versions of 'Wheatland', 'Redlan', 'RTx 430', 'Tx623', 'Tx630', 'Tx631' and the hybrid AWheatland×RTx430. Height, maturity, grain yield and test weight, and stover neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), and in vitro NDF digestibility (IVNDFD) were measured in replicated complete block experiments with gene nested within line in four environments. Brown midrib genes reduced grain yield and residue yield in the lines, however yield reduction was not observed in the bmr-12 AWheatland×RTx430 hybrid. The bmr-12 near-isolines generally had lowest stover lignin content and highest fiber digestibility, bmr-6 was intermediate, and wild-type counterparts had highest lignin content and lowest fiber digestibility. When all data are considered, the bmr-12 gene appears superior to the bmr-6 gene in terms of potentially adding value to grain sorghum for use in crop/animal systems. The variable expression of bmr-12 and bmr-6 in different lines indicates that selection of compatible genetic backgrounds will be critical in determining the realized impact on value.

Last Modified: 9/22/2014
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