Genetic background impacts soluble and cell wall-bound aromatics in brown midrib mutants of sorghum

Palmer, Nathan A.; Sattler, Scott E.; Saathoff, Aaron J.; Funnell, Deanna L.; Pedersen, J. F.; Sarath, Gautam

doi:10.1007/s00425-008-0814-1

Cited by 89 publications

(164 citation statements)

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“…The bmr6 mutation affects the SbCAD2 gene: The increased levels of cinnamaldehyde endgroups in the lignin of the bmr6-ref mutant are consistent with reduced CAD activity (Bucholtz et al 1980;Pillonel et al 1991;Palmer et al 2008;Saballos et al 2008). On the basis of the clustering of SbCAD2 in group I with the bona fide CADs, we hypothesized that the SbCAD2 gene is the main CAD gene in sorghum and that a mutation in this gene would affect lignification.…”

Section: Resultsmentioning

confidence: 97%

“…There are at least four independent bmr loci (Bittinger et al 1981;Saballos et al 2008). One of the mutants, bmr6, displays decreased CAD activity (Bucholtz et al 1980;Palmer et al 2008) and contains cell walls with higher levels of cinnamaldehydes (Pillonel et al 1991;Saballos et al 2008). Aided by the release of the sorghum genome sequence (www.phytozome.net/sorghum), we report here the systematic analysis of the sorghum CAD gene family, its relationship with the gene families from other species, and the identification of the Bmr6 gene.…”

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confidence: 99%

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A Genomewide Analysis of the Cinnamyl Alcohol Dehydrogenase Family in Sorghum [Sorghum bicolor(L.) Moench] IdentifiesSbCAD2as theBrown midrib6Gene

et al. 2009

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The content and composition of the plant cell wall polymer lignin affect plant fitness, carbon sequestration potential, and agro-industrial processing. These characteristics, are heavily influenced by the supply of hydroxycinnamyl alcohol precursors synthesized by the enzyme cinnamyl alcohol dehydrogenase (CAD). In angiosperms, CAD is encoded by a multigene family consisting of members thought to have distinct roles in different stages of plant development. Due to the high sequence similarity among CAD genes, it has been challenging to identify and study the role of the individual genes without a genome sequence. Analysis of the recently released sorghum genome revealed the existence of 14 CAD-like genes at seven genomic locations. Comparisons with maize and rice revealed subtle differences in gene number, arrangement, and expression patterns. Sorghum CAD2 is the predominant CAD involved in lignification based on the phylogenetic relationship with CADs from other species and genetic evidence showing that a set of three allelic brown midrib (bmr) lignin mutants contained mutations in this gene. The impact of the mutations on the structure of the protein was assessed using molecular modeling based on X-ray crystallography data of the closely related Arabidopsis CAD5. The modeling revealed unique changes in structure consistent with the observed phenotypes of the mutants.

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Section: Resultsmentioning

confidence: 97%

mentioning

confidence: 99%

A Genomewide Analysis of the Cinnamyl Alcohol Dehydrogenase Family in Sorghum [Sorghum bicolor(L.) Moench] IdentifiesSbCAD2as theBrown midrib6Gene

et al. 2009

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“…4B). In several previous studies, bmr-6 appeared to have reduced activities of several lignin biosynthesis enzymes, including PAL, COMT, and CAD (Palmer et al 2008, Pillonel et al 1991, Tsuruta et al 2003. To examine the effect of transcript accumulation on activities of these enzymes, we compared transcript levels in N-6 and bmr-6 stems during several developmental stages by using semi-quantitative RT-PCR (Fig.…”

Section: Expression Of Genes Encoding Cad and Other Enzymes In Ligninmentioning

confidence: 85%

“…In sorghum, several distinct mutants were produced by chemical mutagenesis (Porter et al 1978), of which three mutants, bmr-6, bmr-12, and bmr-18, affect lignin content and composition in cell walls, and appeared to be the most promising for improvement of forage quality (Cherney et al 1991, Porter et al 1978. Biochemical analysis has suggested that the alteration of lignin content or composition in these mutants is caused by reductions of the activities of enzymes involved in lignin biosynthesis, such as phenylalanine ammonia-lyase (PAL), caffeic acid O-methyltransferase (COMT), and cinnamyl alcohol dehydrogenase (CAD) during the middle stages of lignification (40 to 60 days after sowing) (Bucholtz et al 1980, Palmer et al 2008, Pillonel et al 1991, Tsuruta et al 2003. In addition, Saballos et al (2009) and Sattler et al (2009) reported that base substitutions resulting in premature stop codons were identified in the coding regions of the genes encoding CAD in sorghum bmr-6 mutants and the binding sites of the enzyme have been changed, which caused the loss of enzymatic activity.…”

Section: Introductionmentioning

confidence: 99%

Structure and expression profile of the cinnamyl alcohol dehydrogenase gene and its association with lignification in the sorghum (Sorghum bicolor (L.) Moench) bmr-6 mutant

et al. 2010

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Lignin, one of the major components of plant cell walls, has negative impacts on forage digestibility and bioethanol production through fermentation. Understanding the regulatory mechanism of lignin biosynthesis is essential to developing plants with altered lignin contents. The sorghum (Sorghum bicolor [L.] Moench) brown-midrib-6 mutant (bmr-6) has reduced levels of several key enzymes in the lignin biosynthesis pathway. Among the genes encoding these enzymes, the gene for cinnamyl alcohol dehydrogenase (CAD; EC 1.1.1.195) contains a nonsense mutation (responsible for bmr-6) that results in reduced CAD gene transcript levels. We found that the CAD coding region was 4225 bp and consisted of four exons separated by three introns. Bioinformatic analysis of the 5′-flanking region identified several putative binding sites for transcription factors. Moreover, a cross-species comparison of CAD genomic DNA sequences revealed evolutionary and structural variation among plant taxa. The expression level of the CAD gene was much lower in bmr-6 than in normal isoline (N-6) in root, stem, leaf, and midrib. Expression levels of other lignin biosynthesis genes were comparable in bmr-6 and N-6. These results suggest that the depression of CAD enzymatic activity in bmr-6 could affect enzymatic activity and post-translational regulation of other enzymes related to lignin biosynthesis.

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“…(2) Molecular analysis of brown midrib mutants Biochemical analysis has suggested that the alteration of lignin content or composition in the brown midrib mutants is due to reduced activities of enzymes involved in lignin biosynthesis, such as phenylalanine ammonialyase (PAL), caffeic acid O-methyltransferase (COMT), and cinnamyl alcohol dehydrogenase (CAD) (Bucholtz et al 1980, Pillonel et al 1991, Tsuruta et al 2003, Palmer et al 2008. The relationships between reduced enzyme activity and gene structure have been studied by molecular characterization of lignification-related genes.…”

Section: Sorghummentioning

confidence: 99%

The Present Status of C<sub>4</sub> Tropical Grasses Breeding and Molecular Approaches

Tsuruta

Shimoda

Kouki³

et al. 2015

JARQ

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Tropical grasses have been widely utilized as warm-season grasses in the warm temperate zone since the early 20th century because of their high yields as well as for perennial forages in their native tropical areas. The high yield of tropical grasses is mainly due to C4 photosynthesis. However, the soaring demands for animal production sparked by economic development in tropical countries mean genetic improvement of such grasses is urgently needed. Considerable breeding efforts have been made to create and develop new tropical grass cultivars, although direct selection from natural populations remains the main method used for breeding. Cross-breeding has not proliferated due to a lack of genetic information concerning the polyploidy, high sterility, outcrossing, and apomixis of these grasses, although several of these difficulties are starting to be resolved by advanced research using molecular biology tools. These tools are an effective means of achieving genetically improving of tropical grasses, and further development is anticipated. In this review, achievements in the improved guineagrass, brachiariagrass, sorghum, and zoysiagrass are introduced and discussed.

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Genetic background impacts soluble and cell wall-bound aromatics in brown midrib mutants of sorghum

Cited by 89 publications

References 48 publications

A Genomewide Analysis of the Cinnamyl Alcohol Dehydrogenase Family in Sorghum [Sorghum bicolor(L.) Moench] IdentifiesSbCAD2as theBrown midrib6Gene

A Genomewide Analysis of the Cinnamyl Alcohol Dehydrogenase Family in Sorghum [Sorghum bicolor(L.) Moench] IdentifiesSbCAD2as theBrown midrib6Gene

Structure and expression profile of the cinnamyl alcohol dehydrogenase gene and its association with lignification in the sorghum (Sorghum bicolor (L.) Moench) bmr-6 mutant

The Present Status of C<sub>4</sub> Tropical Grasses Breeding and Molecular Approaches

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