Abstract
Birch(Betula platyphylla Suk.) bark contains important
pentacyclic triterpenes as betulin and betulinic acid, which play
important functions in anti-tumor and anti-HIV.Cytochrome P450
monooxygenase(CYP450) is essential for the diversification and
functional modification of the triterpene skeleton.In this study, five
new CYP450 genes were cloned from birch with ORF lengths of
1284bp, 1533bp, 1188bp, 1704bp, and 1539bp, respectively.Phylogenetic
tree analysis shown that five BpCYP450 genes are located in five
subfamilies, named CYP94B89, CYP89S1, CYP97B62,
CYP86B54, and CYP86A182.The expression characteristics of
five CYP450 genes in different tissues and their responses to
different stresses(MeJA, SA, GA3, ABA, ethylene, and
mechanical damage) were significantly different, among which
CYP89S1, CYP97B62 and squalene epoxidase(BpSE) and
dammarenediol synthase(BpDS) were highly expressed in
leaves.CYP89S1, CYP97B62, and CYP86A182 genes are
induced by MeJA and significant synergistic expression effects with
lupeol synthase(BpW).CYP89S1, CYP97B62,
CYP86A182 have C-28 oxidation function and catalyzing the
conversion of lupeol to betulinic acid.Among them, CYP97B62 gene
has the highest catalytic efficiency, increasing the content of
betulinic acid by 1136%.In addition, co expression of BpMYB21
and CYP86A182 can significantly enhance the conversion and
synthesis efficiency of betulinic acid in tobacco(Nicotiana
tabacum L.), and CYP89S1 can enhance salt and alkali resistance
in yeast(Saccharomyces cerevisiae)