Abstract: 【Objective】 To explore the relationship among the rutin content at different developmental stages with rutin biosynthesis genes and MYB regulation genes, it will be very meaningful to understand the underlying molecular metabolism of rutin accumulation in tartary buckwheat. 【Method】 The whole developmental stages of F. tatarium Jiujiang were classified into 8 stages (germination, first pair of leaf formation, true leaf growth, vegetative growth, flowering, peak flowering, immature seeds , matured seeds),which were named S1-S8 stages. The whole seedlings from S1and S2 stage, leaves from S3 and S4 stage, flowers from S5 and S6 stage, seed formation organ from S7 and S8 stage were used as test materials. Two MYB genes, FtMYB7 and FtMYB9, were cloned and sequenced. The homologous amino acid sequence and conservative structure domain analysis were carried out by T-coffee software. The phylogenetic tree was constructed by the NJ method (neighbor-joining). The multiple sequence alignment of MYB transcription factors related with flavonoids among Arabidopsis and buckwheat were analyzed by MEGA 7.0 software. The rutin content of these tissues at S1-S8 stages was detected by HPLC. In the meantime, the expression level of rutin-biosynthesis-related genes (FtCHS, FtF3H, Ft4CL, FtFLS-like and FtUFGT) and regulator genes (FtMYB7 and FtMYB9) were investigated by qRT-PCR. The correlation of rutin content and the gene expression pattern during the whole developmental stage was estimated by Pearson correlation method. These data were transformed to matrix data, and constructed a Hierarchical cluster heat map by Euclidean distance method. 【Result】Cloned two MYB transcriptional factors, FtMYB7 and FtMYB9, their nucleic acid sequences were 876 and 912 bp, respectively, encoding 291 and 303 amino acid residues. The sequences of 17 MYB transcription factor from buckwheat, and 3 genes related to flavonoids metabolism in Arabidopsis were constructed for a phylogenetic tree. The phylogenetic tree showed that these genes were divided into six groups. Among them, FtMYB7 belongs to the group II, and FtMYB9 belongs to IV groups, the result indicated that the two MYB transcription factors involved in function diversity at regulation of plant growth and development process. The qRT-PCR results showed that the relative expression levelsof FtMYB7 at S3 and S5 stages were the highest at 501 and 867 times, respectively. To FtMYB9, the highest gene expression levels were detected at S1 and S2 stages, and 34 and 72 times, respectively. Correlation analysis showed that during 8 growth stages, Ft4CL, FtCHS, FtF3H, FtUFGT and FtMYB7 expression patterns were positively correlated with rutin content, and the correlation coefficient was 0.748, 0.683, 0.704, 0.890 and 0.862, respectively. However, FtFLS-like and FtMYB9 were negatively correlated with rutin content, and the correlation coefficients were -0.442 and -0.501, respectively. 【Conclusion】 The FtMYB7 and FtMYB9 were characterized by two R2R3 MYB genes. The different gene expression patterns and rutin content at the whole developmental stage of tartary buckwheat suggested that the FtMYB7 is positively regulated in rutin biosynthesis, but the FtMYB9 is negatively regulated.

Key words: Fagopyrum tataricum, rutin, MYB genes, gene expression