ABSTRACT
Cellulose synthase (CesA), one of the key enzymes in the biosynthesis of cellulose in plants, plays an important role in plant growth and plant resistance. In this study, a total of 21 AsCesA genes from Aquilaria sinensis were systematically identified and the physico-chemical characteristics were analyzed based on genome database and bioinformatical methods. The phylogenetic tree was constructed and the gene location on chromosome, cis-acting elements in the 2 000 basepairs upstream regulatory regions and conservative motifs were analyzed. The AsCesA proteins were mainly located on the plasma membrane. The number of amino acids of the proteins ranged from 390 to 1 261. The isoelectric point distributed from 5.67 to 8.86. All of the 21 AsCesA proteins possessed the transmembrane domains, the number of which was from 6 to 8. The genes were classified into 3 groups according to the phylogenetic relationship. Obvious differences were observed in motif composition in genes from different groups. However, motif2, motif6, motif7 and motif10 were observed in all of AsCesA proteins. Analysis of cis-acting elements indicated that AsCesA genes family has cis-acting elements related to plant hormones, abiotic stresses, and biological processes. Seven AsCesA genes with differential expression were selected according to the calli transcriptome data induced by NaCl at different times and their expression levels under different abiotic stresses were analyzed by quantitative real-time PCR. The results indicated that salt, low temperature, drought, and heavy metal stresses could affect the expression level of AsCesA genes, and the abundance of AsCesA1, AsCesA3 and AsCesA20 showed a significant change, implying their potential important roles to the abiotic stresses. The accumulation pattern of cellulose content under different abiotic stresses was similar to the expression trend of AsCesA genes. Our results provide valuable insights into the role of cellulose synthase in A.sinensis in plant defense.
ABSTRACT
Dihydroflavonol 4-reductase (DFR) plays an essential role in the biosynthesis of anthocyanin and regulation of plant flower color. Based on the transcriptome data of Cistanche tubulosa (Schenk) Wight, a full-length cDNA sequence of CtDFR gene was cloned by reverse transcription-polymerase chain reaction (RT-PCR). CtDFR contains an open reading frame (ORF) of 1 263 bp which encodes 420 amino acids with a predicted molecular weight of 47.5 kDa. The sequence analysis showed that CtDFR contains a nicotinamide adenine dinucleotide phosphate (NADPH) binding domain and a specific substrate binding domain. The expression analysis indicated that CtDFR was highly expressed in red and purple flowers, and the relative expression levels were 4.04 and 19.37 times higher than those of white flowers, respectively. The recombinant CtDFR protein was expressed in E.coli BL21 (DE3) using vector pET-28a-CtDFR and was purified. In vitro enzyme activity analysis, CtDFR could reduce three types of dihydroflavonols including dihydrokaempferol, dihydroquercetin, and dihydromyricetin to leucopelargonidin, leucocyanidin and leucodelphinidin. Subcellular localization analysis showed that CtDFR was mainly localized in the cytoplasm. These results demonstrate that CtDFR plays an important role in regulation of flower color in C. tubulosa and make a valuable contribution for the further investigation on the regulation mechanism of C. tubulosa (Schenk) Wight flower color.