Isolation and Expression Analysis of Two Genes Encoding Cinnamate 4-Hydroxylase from Cotton(Gossypium hirsutum)

Two genes （GhC4H1 and GhC4H2） that encode putative cotton cinnamate 4-hydroxylases that catalyze the second step in the phenylpropanoid pathway were isolated from developing cotton fibers. GhC4H1 and GhC4H2 each contain open reading frames of 1 518 base pairs （bp） in length and both encode proteins consisting of 505 amino acid residues. They are 90.89% identical to each other at the amino acid sequence level and belong to class I of plant C4Hs. GhC4H1 and GhC4H2 genomic DNA are 2 247 and 2 161 bp long, respectively, and contain two introns located at conserved positions relative to the coding sequence. GhC4HI and GhC4H2 promoters were isolated and found to contain many cis-elements （boxes P, L and AC-1 element） previously identified in the promoters of other phenylpropanoid pathway genes. Histochemical staining showed GUS expression driven by the GhC4H1 and GhC4H2 promoters in ovules and fibers tissues. GhC4H1 and GhC4H2 were also widely expressed in other cotton tissues. GhC4H2 expression reached its highest level during the elongation stage of fiber development, whereas GhC4H1 expression increased during the secondary wall development period in cotton fibers. Our results contribute to a better understanding of the biochemical role of GhC4H1 and GhC4H2 in cotton fiber development.

Effects of Temperature on Seed Germination and Metabolism of Scutellaria baicalensis Georgi

[Objectives]To explore the effects of temperature on the primary and secondary metabolism of Scutellaria baicalensis Georgi during the seed germination.[Methods]The superoxide dismutase(SOD)activity was determined using riboflavin-NBT;peroxidase(POD)activity was determined using guaiacol colorimetric method,catalase(CAT),ascorbate peroxidase(APX),phenylalanine ammonia lyase(PAL)and cinnamic acid-4-hydroxylase(C4H)activity were detected by ultraviolet spectrophotometry,and chalcone synthase(CHS)activity and the content of secondary metabolites were measured by high performance liquid chromatography(HPLC).[Results]The germination rate,germination potential and germination index of S.baicalensis seeds were significantly affected by temperature.The most suitable temperature for the germination of S.baicalensis seeds was 25℃.The activities of SOD,POD and CAT in S.baicalensis seeds treated at low and high temperature were higher than that treated at suitable temperature;the activities of PAL,C4H and CHS of S.baicalensis seeds treated at low and high temperature were lower than that treated at suitable temperature.There was a good positive correlation between flavonoids and soluble sugar,PAL activity and C4H activity,and the correlation coefficients were R=0.894*,R=0.956*and R=0.951*,respectively.[Conclusions]In adverse environment,S.baicalensis seeds have good defense capabilities.During the germination of seeds,the formation of secondary metabolites is significantly correlated to the activity of key enzymes.Therefore,high-quality medicinal materials can be obtained by taking measures to improve the activity of key enzymes.

Changes of chlorogenic acid content and its synthesis-associated genes expression in Xuehua pear fruit during development

According to synthetic pathway of plant chlorogenic acid （CGA）, the expression patterns of genes encoding enzymes that are associated with CGA synthesis were studied in normally developed Xuehua pear fruit. The study demonstrated that CGA content in peel and flesh of Xuehua pear decreased as fruit development progressed, with a higher level in peel. The expression levels of PbPAL 1, PbPAL2, PbC3H, PbC4H, Pb4CL 1, Pb4CL2, Pb4CL6, PbHC T1 and PbHC T3 genes decreased in fruit, which was consistent with the pattern of variation in CGA content. That indicated that these genes might be key genes for influencing fruit CGA synthesis in Xuehua pear. However, Pb4CL7 gene expression profile is not consistent with variation of CGA content, hence, it may not be a key gene involved in CGA synthesis.