Function Analysis Of BpCHS Gene In Betula Platyphylla

Chalcone synthase is a key enzyme in the synthesis of flavonoids.It plays an important role in many physiological and biochemical activities.CHS gene can affect the plant leaf color by affecting the synthesis of flavonoids and improve plant resistance.In this study,the bacite synthase gene(BpCHS2,BpCHS3)was cloned and the transgenic Betula platyphylla was obtained by Agrobacterium tumefaciens,and the growth and photosynthetic characteristics of transgenic Betula platyphylla under 0.4%NaCl stress were analyzed.The results are as follows:The BpCHS3 gene has a total length of 1203bp,encoding 400 amino acids,the relative molecular weight of the protein is 99014.5,the theoretical isoelectric point is 5.01,the number of positive and negative charge residues is 0,the molecular formula is C3561H5921N1203O1480S304,the extinction coefficient is 0,the instability coefficient is 46.03,The coefficient of fat was 24.85 and the total average hydrophilicity was 0.811.Multi-sequence alignment shows that the sequence of BpCHS2 was similar to that of pomegranate,Eucalyptus grandis,lotus and so on.The similarity was between 76%and 79%.The plant overexpression vector and the expression vector of BpCHS2 gene were constructed by digestion technique.The genetic transformation of BpCHS was carried out by Agrobacterium tumefaciens-mediated method.Eleven overexpression lines were obtained.PCP,qRT-PCR and Northern hybridization demonstrated that the exogenous gene had been successfully integrated into the birch genome and expressed at the mRNA level.Analysis of growth,endogenous hormones and related gene expression characteristics of BpCHS3 gene lines:Compared with the wild type birch(WT),the bark of BpCHS3 overexpression lines became colorless,the branching of transgenic lines increased obviously,and the number of branches was 1.25 times.The content of IAA and ABA in BpCHS3 overexpression lines was higher than that of wild type birch.The protein content of 2-year-old BpCHS3 overexpressing plants was analyzed.The results were as follows.The content of chlorophyll and carotenoid in the upper and middle leaves of the transgenic plants was lower than that of the wild type birch,the chlorophyll and carotenoid in the leaves of the transgenic plants were higher than those of the wild type birch.The content of anthocyanin in the leaves of the transgenic lines was lower than that of the wild type birch.In the phloem,except for the upper chlorophyll a content of CHS3-1 and CHS3-3,the content of chlorophyll a in the upper and lower part of the other transgenic lines was higher than that of the wild type birch.The content of carotenoids in leaves of transgenic plants was higher than that of wild type white birch,and the content of a/b in transgenic lines was 1.14 times higher than that of wild type birch.In the anthocyanin content,the upper part of the shoots and the lower leaves of the transgenic lines were lower than those of the wild type birch,and the anthocyanin of the wild type birch was 1.21 times of that of the transgenic lines,the content of anthocyanins in the middle part of the phloem was higher than that of the wild type birch,and the anthocyanin of the wild type birch was 1.17 times of that of the transgenic lines.The temporal and spatial expression of related genes in the synthesis pathway of flavonoids in transgenic lines was analyzed.The results are as follows.BpCHS2 and BpCHS3 transgenic lines were mostly higher than those of non-transgenic plants in the synthesis of flavonoids in transgenic lines.BpCHSRi2 and BpCHSRi3 transgenic lines were lower than non-transgenic lines in the synthesis of flavonoids in transgenic lines.The content of CHI and DFR in BpCHS3 transgenic lines was higher than that of non-transgenic lines(82.7 and 38.86),and the content of CHI and DFR in BpCHSRi3 transgenic lines was 0.45 and 0.46 times lower than that of non-transgenic lines.The relative growth,chlorophyll relative content,chlorophyll fluorescence parameters and maximum net photosynthetic rate of the BpCHS3 transgenic lines were measured by 0.4%NaCl salt tolerance.The results showed that the Fv/Fm values of most transgenic lines were still within the normal range at 9 d of NaCl stress on chlorophyll fluorescence parameters.Compared with Od,the decrease of qP and NPQ values of transgenic lines was less than that of non-transgenic lines,which were 1.73 and 1.25 times of non-transgenic lines,while NPQ values were higher than non-transgenic lines,0.61 times of non-transgenic lines.The above studies have shown that transgenic lines show a certain salt tolerance.