Effect of the Brown Midrib‐Allele on Maize Silage Quality and Yield¹

Abstract

High digestible dry matter yield is desired by maize (Zea mays L.) silage producers. The brown midrlb‐3 mutant (bm3) improves the digestibility of maize stover but reduces grain and fodder yields of homozygous bm3 genotypes. Our objective was to estimate the relative genetic potential for improvement of silage quality and yield in bm3 and normal maize populations. A total of 130 bm3 and normal 130 S1 lines were developed from three populations segregating for the bm3 allele. All 260 S1 lines were evaluated at two Minnesota locations in 1978. In 1979, 64 bm3 64 normal S1 lines, and 24 bm3 and 24 normal S1 ✕ S1 hybrids were evaluated at three locations.The bm3 genotypes averaged 77% of the grain yield, 90% of the stover yield and 84% of the fodder yield of the normal genotypes. Some bm3 genotypes produced as much stover as the best normal genotypes. However, no bm3 genotypes produced as much grain or fodder as the best normal genotypes. The normal genotypes yielded 16% more digestible dry matter than the bm3 genotypes. Estimates of genetic variability and predicted genetic gain for digestible dry matter yield were similar for bm3 and normal populations. Even though bm3 germplasm offers a substantial advantage in stover digestibility, our results indicate normal populations of maize may offer more potential for silage breeding programs.

Improvement of biomass through lignin modification

“…For example, some of the maize bm mutants have been reported to have reduced biomass yield (Lee and Brewbaker, 1984;Miller et al, 1983), reduced stalk strength (Zuber et al, 1977) and reduced resistance to pathogens (Nicholson et al, 1976), at least under certain growing conditions or environments. Similarly, strong reduction of the activities of C4H, C3¢H and HCT in alfalfa resulted in dwarf plants with reduced biomass (Reddy et al, 2005; bmr-6 Wild type Shadle et al, 2007).…”

Antisense Down-Regulation of 4CL Expression Alters Lignification, Tree Growth, and Saccharification Potential of Field-Grown Poplar

“…Similarly, discolored wood has also been found when enzyme activity levels either upstream or downstream of 4CL have been altered (Porter et al, 1978;Miller et al, 1983;Baucher et al, 1996;Ralph et al, 1997;Tsai et al, 1998;Lapierre et al, 1999;Meyermans et al, 2000;Pilate et al, 2002;Jourdes et al, 2007;Leplé et al, 2007). Down-regulation of cinnamyl alcohol dehydrogenase, for example, produced red xylem that resulted from small amounts of sinapyl aldehyde entering the xylem cell wall region (Jourdes et al, 2007).…”

“…To gain detailed insights into cell wall assembly, mutant or transgenic perturbations to lignin biosynthesis have been employed to alter native lignin content and monomer compositions (i.e. to shift ratios of syringyl [S], guaiacyl [G], and p-hydroxyphenyl [H] lignins; Porter et al, 1978;Miller et al, 1983;Baucher et al, 1996;Kajita et al, 1996;Lee et al, 1997;Anterola and Lewis, 2002;Davin et al, 2008aDavin et al, , 2008bPatten et al, 2010a). In addition, such perturbations give needed insight into the role of lignin in providing resistance to mechanical (Mark, 1967;Niklas, 1992;Gindl and Teischinger, 2002) and biotic (Dixon and Paiva, 1995) stresses.…”

Genetic and physical fine mapping of the novel brown midrib gene bm6 in maize (Zea mays L.) to a 180 kb region on chromosome 2

“…bm1-4 in maize and bmr6, bmr12, bmr18 in sorghum are characterized by reduced lignin content and altered lignin composition, but they often have negative effects on agronomic traits although genetic background and environment might confound the effects of brown midrib genes (Pedersen et al 2005). Homozygous status of bm3 in maize significantly reduces plant grain and/or forage yield (Miller et al 1983;Cox and Cherney 2001), and plant height (Lee and Brewbaker 1984). Homozygous status of bmr6 and bmr18 in sorghum might also suppress plant height compared with the normal isogenic lines (Casler et al 2003;Oliver et al 2005a, b).…”