The leucoanthocyantin reducase (LAR) gene, an important functional gene of catechins biosynthesis pathway, was cloned from Fagopyrum dibotrys (D.Don) Hara by degenerate PCR and rapid amplification of cDNA ends (RACE). The full-length cDNA of FdLAR is 1 581 bp (GenBank accession: JN793953), containing a 1 176 bp ORF encoding a 391 amino acids protein, and its 3'-untranslated region has an obvious polyadenylation signal. The recombinant plasmid containing FdLAR completed ORF was transformed into E. coli BL21 (DE3). The target fusion peptide with molecular weight of 66 kD was expressed under the condition of 16 degrees C and induced by IPTG at final concentration of 1.0 mmol x L(-1). Bioinformation analysis indicated that the amino acid sequence of FdLAR showed great homology to other LAR with the NADB-Rossmann conversed domain in the N-terminus. Real-time quantitative PCR was used to detect the expression levels of FdLAR gene during different development periods. The determination of flavonoids contents in appropriate rhizomes showed that the relationship between FdLAR gene expression and the accumulation of flavonoids displayed different trends during vegetative growth and reproductive growth stages, suggesting that the FdLAR gene may be involved in the pathway of flavonoid metabolisms in Fagopyrum dibotrys.

Leaf senescence is considered as one of important factors to decrease ornamental values of foliage plants. In the attempt to study and understand the molecular mechanism of leaf senescence, a senescent leaf cDNA library of Coleus blumei was constructed and a small EST library was obtained. According to the sequence of an EST fragment with a cystathionine beta synthase (CBS) domain, a novel leaf senescenceassociated gene (SAG) full-length cDNA encoding a CBS-domain-containing protein, denoted Cbcbs, was rapidly cloned using a strategy of RACE combined with cDNA library. The full length of the Cbcbs gene was 859 bp long (accession No. EF076754) and contained a 609 bp open reading frame (ORF) encoding a 202amino acid protein. One stop codon (TAA) was found in 5' UTR and one possible polyadenylation signal,AATAAA, and a pentanucleotide motif, ATTTA, were found in 3' UTR. The CbCBS contained a predicted mitochondrial targeting peptide in the N-terminal region, two conserved and intact CBS domains, four casein kinase Ⅱ (CK Ⅱ) phosphorylation sites, three protein kinase c (PKC) phosphorylation sites and one tyrosine sulfation (TS) site. Sequence comparisons and phylogenetic analysis showed that CbCBS was a novel senescence or stress-associated protein. The prediction analysis of secondary structure and three dimensional structure of CbCBS suggested that the chief function of the protein was decided by the CBS domain pair. The expression pattern of Cbcbs in leaves was analyzed by RT-PCR. It was demonstrated that Cbcbs gene was a senescence-associated gene (SAG) and expressed in all leaf stages, young stage (Y) being the lowest and terminal senescence stage (S3) being the highest, and was upregulated along with the leaf senescence.Function analysis showed that the mature CbCBS maybe acts as a sensor of cellular energy status and directly or indirectly regulates cellular energy levels to increase ATP content in mitochondria during periods of metabolic stress of senescent leaves.

Using RACE with a Fagopyrum dibotrys callus cDNA library, one clone, named FdMYBP1, encoding a putative R2R3 MYB protein was identified. FdMYBP1 appeared to be a full-length cDNA of 1159 bp encoding a protein of 265 amino acids. Through structure and property analysis of FdMYBPI with bioinformational methods, it was found that the amino acid sequence of FdMYBP1 showed great homology to other MYBP with the R2R3 repeat region in the N-terminus. Southern blot analysis indicated that FdMYBP1 belongs to a single copy gene in F. dibotrys genomes. The FdMYBP1 gene has the same classic characters with other MYBP and probably involved in the pathway of flavonoid metabolisms.
Cloning, Molecular ; Fagopyrum ; genetics ; metabolism ; Gene Expression Regulation, Plant ; Molecular Sequence Data ; Plant Proteins ; genetics ; metabolism ; Proto-Oncogene Proteins c-myb ; genetics ; metabolism

OBJECTIVETo establish a method for isolation of the total RNA from Fagopyrum cymosum callus.

METHODThe improved method combining that of CTAB extraction with the LiCl precipitation was used to isolate the total RNA from the four F. cymosum callus. The quality of the RNA was detected by UV spectrophotometric analysis, 0.8% non-denaturing agarose gel electrophoresis and RNA reverse transcription.

RESULTThe bands of 28S and 18S could be seen clearly by agarose gel electrophoresis, and the value of A260/A280 was between 1.9 and 2.0. The cDNA which was reverse-transcribed by the total RNA showed a wide length rage of 500 bp-5 kb.

CONCLUSIONThe RNA extracted by this method meets the requirement of reverse transcription-polymerase chain reaction (RT-PCR), construction of cDNA libraries, et al. This improved method can be used to isolate the total RNA from F. cymosum callus with the advantage of simpleness, efficiency and low cost.

Fagopyrum ; genetics ; growth & development ; RNA, Plant ; analysis ; isolation & purification