Lignin Biosynthesis And The Expression Of Related Genes In Rosa Roxburghii Tratt

Cili(Rosa roxburghii Tratt)was rich in dietary fiber. Especially, the lignin was the only component which barly to biochemical decompose. Therefore the high content of lignin will inevitably lead to poor fruit taste, texture and low juice yield, seriously affect the quality of fresh and processed products. Although higher plant lignin synthesis approach has been basically illuminated, but the research of lignin accumulation process and its molecular biological mechanism in Cili has not been involved. Rose roxburghii Tratt was used to investigate the lignin components, accumulation pattern, related synthetase activity and gene expression level, in order to afford more informations about the molecular and physiological mechanism of lignin biosynthesis and regulation on the basis of further analyzing the relationship between them. The main results were as follows:(1)Lignin accumulation in the process of fruit development of Cili Young fruit(before 40 d after anthesis)contained the highest lignin content during whole growth period, then it showed a trend of rapid decline as the fruit rapid growth. After 70 d after anthesis, the trend of decline droped by moderate, when fruit ripe, it’s lignin only contented about 15% of the young fruit. The determination of different parts of fruit lignin content and Wiesner staining showed that two-thirds of the lignin mainly accumulated in the prickly skin part in the fruit, lignin content in the peeled pulp only accounted for about a third of the total, and clearly, its depositional model was: fibrous extensions start from thorn to pericarp and finally to pulp.(2)lignin monomer type of Cili fruit The HPLC analysis of two types of lignin monomer:Coniferyl alcohol(G)-type monomers and sinapyl alcohol(S)-type monomer indicated that, although the two kinds of monomer content in the pulp changed differently(in the early developmental, coniferyl alcohol content is higher, but in the ripe fruit, sinapyl alcohol content is higher), there was little difference on the change trend of whole fruit and prickly skin, all of them showed a reduced after the first rise, and highly consistented with changes of lignin. The ratio among the range of 1~3, lignin in Cili fruit was G-S type.(3)The change of enzyme activity and it’s relationship with lignin content in the process of Cili lignin accumulation The analysis of related enzymes activity whichinvolved in lignin synthesis indicated that, in both the whole fruit and prickly skin of fruit,the changing trend of C4 H and 4CL’s activity, which in upstream of Synthetic way, highly consistented with the change of the two monomers. Especially at the early stage of the fruit development(before 40 d after anthesis); POD, which was responsible for the monomer polymerization, also performanced with the highest activity during the development(after that it drastically reduced to almost can’t detect). This suggested that early fruit development before(before 40 d after anthesis) was the main period of lignin monomer synthesis and polymerization in Cili fruit. C4 H and 4CL was the key enzymes.(4) The relationship between the expression of Rosa roxburghii fruit genes involved in lignin biosynthesis and lignin accumulation On the basis of prophase transcriptome sequencing data, we obtained eleven genes’ cDNA sequence in lignin biosynthesis pathway by adopting the method of RT-PCR, including three genes of public phenylalanine metabolic pathway: PAL, C4 H, 4CL and seven genes of lignin specific synthesis way: HCT, C3 H, COMT, CCoAOMT, F5 H, CCR, CAD and POD, involved in lignin monomer polymerization. Through the qRT-PCR, we analyzed the changes of gene relative expression in the process of fruit development and its relationship with lignin synthesis. The results showed that, the expression level of PAL, C4 H and 4CL fell sharply after the first rapid increase, in line with two kinds of monomer and lignin accumulation trend, once again, it showed the importance of upstream genes in regulating monomer synthesis. And HCT, C3 H, COMT, CCoAOMT and F5 H genes, which in lignin specific synthetic way, were rapidly rising during the monomer rapidly accumulated period(10-40 d after anthesis), showed the consistent synergy. In the whole course of development, the expression of C3 H and CCoAOMT both with monomer or lignin was significantly positive correlation, while the F5 H, CCR, CAD and POD genes expression showed a significant increase in the late fruit development, they may also participate in the metabolic processes of other substances.