Analysis on structure and expression pattern of BpHMGR gene in Betula platyphylla Effect of fungal elicitors on N and P utilization and triterpene synthesis of Betula platyphylla suspension cell culture system Diarylheptanoids from leaves of Betula platyphylla Bioinformatics and expression pattern analysis of BpNOS gene in Betula platyphylla Effects of salicylic acid on accumulation of oleanolic acid and defense enzyme activity in suspension cells of Betula platyphylla Effects of salicylic acid on accumulation of oleanolic acid and defense enzyme activity in suspension cells of Betula platyphylla Accumulative characteristics of triterpenoid precursor and different triterpenoid branch products in Betula platyphylla Interaction between putrescine and hydrogen peroxide on regulating triterpenoid production in Betula platyphylla Cloning and Sequence Analysis of Full-length cDNA of Actin Gene from Birch(Betula platyphylla Suk.) Effects of Water,Nitrogen and Methyl Jasmonate Treatment on Triterpenes Accumulation in Birch (Betula platyphylla Suk.) Polyamine-mediated triterpenoid synthesis in suspension cells of Betula platyphylla induced by fungal elicitor Effect of putrescine on sucrose metabolism and triterpenoid accumulation in Betula platyphylla suspension cells Effect of polyamine on growth of Betula platyphylla suspension cells and triterpenoid accumulation