真菌诱导子促进白桦悬浮细胞三萜的积累

Accumulation of Triterpenoids in Betula platyphylla Suspension Culture Induced by a Fungal Elicitor

将促进白桦三萜积累的拟茎点霉属的内生真菌诱导子添加到白桦悬浮培养体系中,研究40,100,400μg·mL-1的真菌诱导子对生长初期、指数生长期和生长末期的悬浮细胞干质量和三萜积累的影响。结果表明:真菌诱导子的不同诱导方案均促进白桦悬浮细胞中三萜的积累,而细胞干质量积累却被抑制;其中最佳诱导条件为在指数生长期的白桦细胞中添加40μg·mL-1的真菌诱导子诱导1天,诱导后细胞中的三萜含量达29.47mg·g-1,比对照增长78%。在优化诱导条件下,考察培养液pH和电导率、细胞苯丙氨酸解氨酶(PAL)和过氧化物酶(POD)活性,发现真菌诱导后6～10h内,引发培养液的碱化和电导率的升高,特别是白桦细胞中PAL和POD酶活性均显著高于对照,分别是对照的5.70倍和5.74倍。研究结果初步说明真菌引发白桦悬浮细胞的防御反应,苯丙烷类代谢途径和氧迸发可能参与真菌诱导三萜的合成。

Endophytic fungus of Phomopsis isolated from birch（Betula platyphylla） bark can be used as an elicitor to induce accumulation of triterpenoids in birch cell suspension culture. The change of dry weight and triterpenoids content of birch suspension cell were investigated at early growth phase, exponential growth phase and late growth phase after a fungal elicitor of 40, 100, and 400 μg·mL-1 concentration was added to birch suspension cells. Results showed that different induction schemes all promoted accumulation of triterpenoids, while the treatments reduced the dry weight of birch cells. Suspension cells at exponential growth phase were most easy to be induced, and 40 μg·mL-1 fungal elicitor enhanced the triterpenoids content to 29.47 mg·g-1, increasing by 78% than that of the control. We investigated changes in pH and conductivity of the medium, and the activity of phenylalanine ammonialyase （PAL） and peroxidase （POD） under the optimal induction condition. Results showed that the fungal elicitor induced alkalinization of the medium and increased the conductivity, and significantly increased the activity of PAL and POD of birch suspension cells, which was 5.70 and 5.74 fold as high as the control after 6-10 h of treatment, respectively. These results suggested that fungal elicitation induced defense reaction in birch suspension cell. General phenylpropanoid pathway and oxidative burst might involved in the triterpenoids accumulation induced by the fungal elicitor.