title: Identification of differentially expressed genes in sorghum (Sorghum bicolor) brown midrib mutants.
abstract: Sorghum, a species able to produce a high yield of biomass and tolerate both drought and poor soil fertility, is considered to be a potential bioenergy crop candidate. The reduced lignin content characteristic of brown midrib (bmr) mutants improves the efficiency of bioethanol conversion from biomass. Suppression subtractive hybridization combined with cDNA microarray profiling was performed to characterize differential gene expression in a set of 13 bmr mutants, which accumulate significantly less lignin than the wild-type plant BTx623. Among the 153 differentially expressed genes identified, 43 were upregulated and 110 downregulated in the mutants. A semi-quantitative RT-PCR analysis applied to 12 of these genes largely validated the microarray analysis data. The transcript abundance of genes encoding l-phenylalanine ammonia lyase and cinnamyl alcohol dehydrogenase was less in the mutants than in the wild type, consistent with the expectation that both enzymes are associated with lignin synthesis. However, the gene responsible for the lignin synthesis enzyme cinnamic acid 4-hydroxylase was upregulated in the mutants, indicating that the production of monolignol from l-phenylalanine may involve more than one pathway. The identity of the differentially expressed genes could be useful for breeding sorghum with improved efficiency of bioethanol conversion from lignocellulosic biomass.
authors.affiliation: The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Sciences, Shandong University, Jinan 250100, PR China.
authors.forename: Li
authors.initials: L
authors.lastname: Yan
authors.forename: Shuwei
authors.initials: S
authors.lastname: Liu
authors.forename: Shuangyi
authors.initials: S
authors.lastname: Zhao
authors.forename: Yali
authors.initials: Y
authors.lastname: Kang
authors.forename: Duoxiang
authors.initials: D
authors.lastname: Wang
authors.forename: Tongwei
authors.initials: T
authors.lastname: Gu
authors.forename: Zhanguo
authors.initials: Z
authors.lastname: Xin
authors.forename: Guangmin
authors.initials: G
authors.lastname: Xia
authors.forename: Yinghua
authors.initials: Y
authors.lastname: Huang
mesh_terms: D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008031:Lignin / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D010649:Phenylalanine / Q000378:metabolism; D010650:Phenylalanine Ammonia-Lyase / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D045868:Sorghum / Q000201:enzymology / Q000235:genetics*; D050564:Trans-Cinnamate 4-Monooxygenase / Q000235:genetics / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D010649:Phenylalanine; D008031:Lignin; D000429:Alcohol Oxidoreductases; C018656:cinnamyl alcohol dehydrogenase; D050564:Trans-Cinnamate 4-Monooxygenase; D010650:Phenylalanine Ammonia-Lyase