茉莉酸甲酯对甘草根次生代谢的调控
Regulation of methyl jasmonate on secondary metabolism of Glycyrrhiza uralensis root
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摘要: 为探讨茉莉酸甲酯（MeJA）对甘草根次生代谢的调控及其机制，分别用20、50、100 μmol/L 的MeJA 喷施甘草叶片，高效液相色谱法测定甘草根中甘草酸和甘草苷等有效成分含量，实时荧光定量PCR法分析甘草根次生代谢途径重要酶β- 香树脂醇合酶（GubAS）、β- 香树脂醇-11- 氧化酶（GubAO）、6- 脱氧查尔酮合酶（GuDOCS）基因的相对表达水平。结果表明，20、50 μmol/L MeJA 溶液处理的甘草酸含量得到极显著提高，100 μmol/L MeJA 溶液处理的甘草酸含量与对照无显著差异；20、50 μmol/L MeJA溶液对甘草苷的积累没有显著影响，而100 μmol/L MeJA 溶液处理的甘草苷含量降低。20 μmol/L MeJA 溶液处理甘草0～6 h 对GubAS、GuDOCS 基因的表达均有促进作用，处理2～6 h 对GubAO 的表达也有促进作用；50 μmol/L MeJA 溶液处理0～2 h 对GubAS、GubAO、GuDOCS 基因的表达水平都有提高作用，但随着处理时间延长，3 个基因表达均恢复处理前水平；100 μmol/L MeJA 溶液对GubAS 和GubAO 表达均无显著影响，GuDOCS 表达量在100 μmol/L MeJA 溶液处理2 h 时得到提高，随后逐渐下降，并在处理24 h 后出现降低现象。推断中低浓度MeJA 在处理初期对甘草有效成分生物合成水平有上调的作用，随着处理浓度提高与时间延长，MeJA 的促进作用逐渐减弱，甚至出现抑制现象。Abstract: To investigate the regulation mechanism of methyl jasmonate（ MeJA） on secondary metabolism of Glycyrrhiza uralensis root，the G. uralensis seedlings were treated by 20，50，100 μmol/L MeJA. After 9 d， the contents of active ingredients in G. uralensis roots were detected by high performance liquid chromatography （HPLC）. And the expression patterns of key enzymes on biosynthetic pathway in G. uralensis roots treated by MeJA for 0，2，6，12，24，36，72 h were analyzed by real-time PCR. The results showed that the contents of glycyrrhizic acid in G. uralensis roots improved in both middle and low concentrations of MeJA，whereas the contents of liquiritin reduced in high concentrations of MeJA. The expression of GubAS，GubAO in G. uralensis roots were promoted by 20 and 50 μmol/L MeJA，and the expression of GuDOCS was promoted by 20 μmol/L MeJA. However，100 μmol/L.MeJA suppressed GubAS and GuDOCS expression. All three genes expression reached the highest level at 6 h under the induction of 20 μmol/L MeJA. It can be concluded that MeJA in middle and low concentrations have the upregulation effect on biosynthesis of glycyrrhizic acid. However only low concentration can promote the biosynthesis of liquiritin.
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