The Research Of Transcription Factors SbLIM1and SbbHLH1in Lignin Metabolic Pathways Of Sorghum Bicolor

The fossil energy reserves are limited, greatly increase of consumption made energy crisis even worse, and will be impact environment adversely. Situation in China is more severe because of its large population; Looking for new alternative energy will be the only way in the future. Bioenergy is a form of renewable energy, and environmentally friendly. Sweet sorghum has multiple resistance, strong adaptability, high stalk sugar content and high biamass, therefore it has been broadly considered as a new energy crops.Lignocellulose is difficult to be degraded due to its complex structure, which is still the biggest obstacle for the conversion of biomass feedstocks to bioenergy. Approaches of molecular biology and genetics let us to make lower lignin content biomass and high S/G lignin biomass which were easier to converse to bioenergy. In this work, we try to understand the role of the two genes, SbLIM1and SbbHLHl, in the lignin metabolism.We construct expression vector, fused SbLIM1with GFP gene, and transient expression in onion epidermal and Arabidopsis protoplast to carry out the subcellular localization of SbLIMl,the results showed that the gene product was the nucleus and cytoplasm. We also construct the yeast expression vector, of SbLIMl, to determine its transcription activity, in vitro,but got negative result.; We got two SbbHLH1high expression lines (OE2and OE3)of Arabidopsis,and found no phenotypic differences between it and wild-type, but the lignin content of the stem of two lines in six to eight weeks was reduced significantly, Wiesner staining also shows the light color in xylem. The At4CL in phenylpropanoid pathway, AtFS’H in flavonoid/anthocyanin biosynthetic pathway, and AtSGT in lignin monomer synthesis pathway were inhibited simultaneously,AtF5H(5G) in branched pathway of lignin monomer synthesis is also down-regulated, while the transcription factor of lignin metabolic regulation AtMYB46and AtMYB83are also inhibited. These results indicate that, SbLIMl involved in lignin metabolic regulation indeed, but the accurate regulatory mechanisms need to be elucidated.The SbbHLHl is a negative regulator in the lignin metabolism. In this paper we intend to explore the target sequence of this transcriptional factor through selex. SbbHLHl had been cloned into prokaryotic expression vector PET-32a,after transformed to E. coli BL21(DE3), and induced with IPTG, SbbHLH1recombinant proteins was purified with higher purity due to its His tag. This is very important step for SbbHLHl in screening its DNA-binding sites and finding interaction proteins.