Forage Quality Characterization of a Chemically Induced Brown‐Midrib Mutant in Pearl Millet

Abstract

Based on the negative relationship between lignin and digestibility, one of the most effective means of increasing forage digestibility is by reducing lignin content. Our objective was to chemically induce a brown‐midrib (bmr) mutation in pearl millet, Pennisetum americanum (L.) Leeke, and evaluate the resulting mutants for lignin content and similarity to existing bmr mutants in other species. Seeds from two inbred pearl millet lines derived from Tift 23D2B1/2 ✕ PI 185642 were treated with either ethyl methyl sulfonate or diethyl sulfate, planted, and selfed in 1984. In 1985 a single plant in one head row exhibited a brown‐midrib phenotype, and was selfed. The bmr pearl millet was compared to selfed normal plants from the same head row along with bmr and normal sorghum, Sorghum bicolor (L.) Moench., and maize, Zea mays L., in 1986 at two locations. Plants were harvested at anthesis and analyzed for apparent in vitro dry matter digestibility (IVDMD), permanganate lignin, alkali‐labile phenolics, and other quality parameters. Lignin concentration in bmr pearl millet was 40 g kg−1 compared to 50 g kg−1 for its normal counterpart, and IVDMD was 726 g kg−1 for the bmr genotype compared to 659 g kg−1 for the normal genotype. The differences in phenolic monomer concentrations between normal and bmr pearl millet were more like those in sorghum than maize. Based on IVDMD, lignin and phenolic monomer analyses, we concluded that bmr pearl millet was similar phenotypically to bmr mutants in sorghum. This trait has excellent potential for improving the quality of forage pearl millet.

Chemical composition and in situ ruminal nutrient degradability of normal and brown midrib forage pearl millet grown in southwestern Québec

“…In contrast to our results, Cherney et al (1990) reported lower NDF and ADF in the second than in the first harvest for bmr, but not for normal forage millet. Our NDF and ADF values for bmr forage millet are in agreement with those reported by Cherney et al (1988), however, our ADL values were at least 50% lower than those reported by the same authors.…”

“…However, ADF was similar for both types of forage millet. Our results are consistent with other studies that showed lower NDF and ADL for bmr millet, sorghum and corn compared with their normal counterparts (Fritz et al 1981;Cherney et al 1988;Cherney et al 1990). Harvest had no effect on NDF, ADF, and ADL.…”

“…The difference in CP content between the two harvests was greater for the bmr than normal forage millet. Differences in CP content between bmr and normal genotypes have been reported for forage millet but not for forage sorghum or corn (Weller et al 1984;Cherney et al 1988). Cherney et al (1990) reported a trend for lower CP for the second than the first harvest for bmr and normal forage millet.…”

“…Brown midrib cultivars have been extensively studied in other species including corn and sorghum, and more recently pearl millet (Cherney et al 1990). This trait has been reported to decrease the lignin content and increase fiber digestibility of forage, but also to reduce forage yields (Cherney et al 1988(Cherney et al , 1990(Cherney et al , 1991Casler et al 2003). The objectives of our study were to determine chemical composition and in situ ruminal degradability of normal and bmr forage pearl millet grown under southwestern Quebec conditions.…”

Opportunities and roadblocks in utilizing forages and small grains for liquid fuels

“…For example, the commonly utilized brown midrib mutants (bmr) in forage maize and sorghum are mutations in genes for enzymes of the lignin biosynthesis pathway resulting in plants with reduced lignin and greater digestibility [1,2,6,8,13,14,19,20,33,36,38,47,75,105]. This suggests that accessibility of cellulose and hemicellulose by rumen microorganisms has been improved by lowering or changing the types and amounts of lignin present in cell walls.…”