Identification and expression analysis of cellulose synthase family genes in Aquilaria sinensis / 药学学报

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.

Cloning and expression analysis of cytochrome P450 AsCYP71D1 from Aquilaria sinensis (Lour.) Gilg / 药学学报

Cytochrome P450 (CYP450) is a kind of superfamily oxidase containing heme, which is distributed in various aerobic organisms. They are widely involved in the biosynthesis of terpenoids, alkaloids, flavonoids, fatty acids, etc. In this study, the full-length cDNA sequence of a P450 was cloned by reverse transcription-PCR (RT-PCR) and rapid amplification of cDNA ends (RACE) technology, with the specific primers that designed according to the sequence of a transcript annotated as P450 from the Aquilaria sinensis (Lour.) Gilg transcriptome database. The tissue expression and subcellular localization were also studied. The full-length cDNA of the cloned P450 gene is 1 920 bp, with 88 bp 5′-untranslated region (UTR), 344 bp 3′-UTR and a 21 bp polyA tail, and 1 488 bp open reading frame (ORF), encoding 495 amino acids. Sequence alignment revealed that the protein belonged to CYP71D family of cytochrome P450 family, and named AsCYP71D1. Tissue expression analysis indicated that AsCYP71D1 was mainly expressed in stem. Further subcellular localization of onion epidermis showed that AsCYP71D1 was expressed in cytoplasm, nucleus and cell membrane. This study will provide a foundation for further research on its function in agarwood sesquiterpene biosynthesis.

Cloning, expression and functional identification of cytochrome P450 reductase gene in Aquilaria sinensis / 药学学报

Cytochrome P450 reductase (CPR) is essential for the electron transport chain of cytochrome P450s, playing an indispensable role in electron transfer in vivo. In this study, one cDNA encoding cytochrome P450 reductase (Ascpr1) was identified from the callus of Aquilaria sinensis. Ascpr1 contains an open reading frame of 2 124 bp. The deduced protein is composed of 707 amino acids, with a predicted molecular weight of 78.82 kD. Phylogenetic analysis revealed that AsCPR1 is a type Ⅱ CPR protein closely related to the CPR from Theobroma cacao. Transmembrane prediction using TMHMM 2.0 indicated that the amino acids 52-71 of AsCPR1 comprise a transmembrane region. After truncating of 67 amino acid residues from N-terminal, the truncated AsCPR1 was successfully expressed in E. coli Transetta (DE3). Further purification of the recombinant AsCPR1 by affinity chromatography and determination of the enzymatic activity allowed the reducing ability of AsCPR1 to cytochrome C in vitro. The results pave the way for further study on the synthesis of defensive chemicals involved in P450s and the functions of CPR in self-defense of A. sinensis.

Cloning and expression analysis of chalcone isomerase from Aquilaria sinensis / 药学学报

Chalcone isomerases (CHIs) play an essential role in the biosynthesis of flavonoids important in plant self-defense. Based on the transcriptome data of Aquilaria sinensis Calli, a full-length cDNA sequence of CHI1 (termed as AsCHI1) was cloned by reverse transcription PCR. AsCHI1 contains a complete open frame (ORF) of 654 bp. The deduced protein is composed of 217 amino acids, with a predicted molecular weight of 23.11 kDa. The sequence alignment and phylogenetic analysis revealed that AsCHI1 has conserved most of the active site residues in type I CHIs, indicating a close relationship with the CHI from Gossypium hirsutum. The recombinant AsCHI1 protein was obtained by heterologous expression of AsCHI1 in E. coli BL21(DE3). The purified AsCHI1 protein exhibited CHI activity by catalyzing the production of naringenin from naringenin chalcone. Remarkably, AsCHI1 expression in A. sinensis Calli treated with various abiotic stresses including salt, mannitol, cold, and heavy metals could be markedly increased, and plant hormones such as abscisic acid (ABA), gibberellin (GA3), and salicylic acid (SA) could also increase the expression of AsCHI1, suggesting that AsCHI1 might play an important role in plant self-defense. The results expand our understanding of the biosynthesis of flavonoids in A. sinensis and give further insight into the defensive responses of A. sinensis to abiotic and biotic stresses.

Gene cloning, subcellular localization and expression analysis of the AsERF1 gene from Aquilaria sinensis / 药学学报

Ethylene-response factors, which are a subfamily of the AP2/ERF family, play an important role in ethylene signal transduction, plant growth and plant resistant. In this study, a full-length cDNA of the AsERF1 gene was cloned from Aquilaria sinensis. Sequence analysis, prokaryotic expression and purification, subcellular localization, tissue-specific analysis and expression analysis under different abiotic stresses was performed. The open reading frame (ORF) of the AsERF1 gene was 691 bp, encoding a protein of 229 amino acids with a predicted molecular mass of 25.36 kD. The AsERF1 protein contained the conserved AP2 sequence of ERF protein. A phylogenetic analysis indicated that the AsERF1 protein showed greatest sequence similarity with ERF2 from Populus trichocarpa. The recombinant AsERF1 protein was expressed in Escherichia coli BL21(DE3) cells using the prokaryotic expression vector pET28a-AsERF1 and the recombinant AsERF1 protein was purified. Agrobacterium-mediated protein expression experiments demonstrated that AsERF1 mainly localized to the nucleus. Expression analysis indicated that AsERF1 was primarily observed in leaves. The AsERF1 expression level was induced by salt, drought, low temperature and CdCl2 treatment, while the abundance of AsERF1 was most significantly induced by drought stress. These results provide valuable insights into the role of AsERF1 in plant defense and the mechanism of agarwood formation.