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G3 (Bethesda). 2014 Sep 2;4(11):2115-24. doi: 10.1534/g3.114.014001.

Characterization of novel Sorghum brown midrib mutants from an EMS-mutagenized population.

Author information

1
Grain, Forage and Bioenergy Research Unit, USDA-ARS, Lincoln, Nebraska 68583 Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, Nebraska 68583 Scott.Sattler@ars.usda.gov.
2
Agronomy Department and Genetics Institute, University of Florida, Gainesville, Florida 32610.
3
Plant Stress and Germplasm Development Unit, USDA-ARS, Lubbock, Texas 79415.
4
Grain, Forage and Bioenergy Research Unit, USDA-ARS, Lincoln, Nebraska 68583 Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, Nebraska 68583.
5
Department of Microbiology and Cell Science and Genetics Institute, University of Florida, Gainesville, Florida 32610.
6
Grain, Forage and Bioenergy Research Unit, USDA-ARS, Lincoln, Nebraska 68583 Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, Nebraska 68583.

Abstract

Reducing lignin concentration in lignocellulosic biomass can increase forage digestibility for ruminant livestock and saccharification yields of biomass for bioenergy. In sorghum (Sorghum bicolor (L.) Moench) and several other C4 grasses, brown midrib (bmr) mutants have been shown to reduce lignin concentration. Putative bmr mutants isolated from an EMS-mutagenized population were characterized and classified based on their leaf midrib phenotype and allelism tests with the previously described sorghum bmr mutants bmr2, bmr6, and bmr12. These tests resulted in the identification of additional alleles of bmr2, bmr6, and bmr12, and, in addition, six bmr mutants were identified that were not allelic to these previously described loci. Further allelism testing among these six bmr mutants showed that they represented four novel bmr loci. Based on this study, the number of bmr loci uncovered in sorghum has doubled. The impact of these lines on agronomic traits and lignocellulosic composition was assessed in a 2-yr field study. Overall, most of the identified bmr lines showed reduced lignin concentration of their biomass relative to wild-type (WT). Effects of the six new bmr mutants on enzymatic saccharification of lignocellulosic materials were determined, but the amount of glucose released from the stover was similar to WT in all cases. Like bmr2, bmr6, and bmr12, these mutants may affect monolignol biosynthesis and may be useful for bioenergy and forage improvement when stacked together or in combination with the three previously described bmr alleles.

KEYWORDS:

acid detergent lignin (ADL); allelism; bioenergy; ethyl methanesulfonate (EMS); forage composition

PMID:
25187038
PMCID:
PMC4232537
DOI:
10.1534/g3.114.014001
[Indexed for MEDLINE]
Free PMC Article

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