title: Map-based cloning and expression analysis of BMR-6 in sorghum.
abstract: Brown midrib mutants in sorghum are associated with reduced lignin content and increased cell wall digestibility. In this study, we characterized a bmr-6 sorghum mutant, which shows reddish pigment in the midrib and stem after the fifth-leaf stage. Compared to wild type, Kalson lignin content of bmr-6 is decreased significantly. We used histological analysis to determine that the mutant exhibited a modified pattern of lignin staining and found an increased polysaccharide content. We cloned BMR-6 gene, a gene encoded a cinnamyl alcohol dehydrogenase (CAD), using a map-based cloning approach. Genetic complementation confirmed that CAD is responsible for the BMR-6 phenotype. BMR-6 gene was expressed in all tested sorghum tissues, with the highest being in midrib and stem. Transient expression assays in Nicotiana benthamiana leaves demonstrated cytomplasmic localization of BMR-6. We found that the expression level of bmr-6 was significantly decreased in the mutant but expression of SbCAD3 and SbCAD5 were significantly increased. Our results indicate that BMR-6 not only affects the distribution of lignin but also the biosynthesis of lignin in sorghum.
authors.affiliation: College of Agriculture, Anhui Science and Technology University, Fengyang 233100, People's Republic of China. qwzhan@163.com.
authors.forename: Jieqin
authors.initials: J
authors.lastname: Li
authors.forename: Lihua
authors.initials: L
authors.lastname: Wang
authors.forename: Qiuwen
authors.initials: Q
authors.lastname: Zhang
authors.forename: Yanlong
authors.initials: Y
authors.lastname: Liu
mesh_terms: D001483:Base Sequence; D002874:Chromosome Mapping; D020090:Chromosome Segregation / Q000235:genetics; D003001:Cloning, Molecular / Q000379:methods*; D003433:Crosses, Genetic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005816:Genetic Complementation Test; D056426:Genetic Loci; D008969:Molecular Sequence Data; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D019655:Quantitative Trait, Heritable; D015203:Reproducibility of Results; D045868:Sorghum / Q000166:cytology / Q000235:genetics*; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D010940:Plant Proteins