Department of Plant Physiology, Campus Miguel de Unamuno, University of Salamanca, E-37007 Salamanca, Spain.
J Exp Bot. 2010 Mar;61(3):747-54. doi: 10.1093/jxb/erp339. Epub 2009 Dec 9.
The flavonolignan silymarin is released to the extracellular medium of Silybum marianum cultures and its production can be stimulated by the elicitor methyljasmonate (MeJA). The sequence of the signalling processes leading to this response is unknown at present. It is reported in this work that MeJA increased the activity of the enzyme phospholipase D (PLD). Treatment with mastoparan (Mst), a PLD activity stimulator, also enhanced PLD and caused a substantial increase in silymarin production. The application of the product of PLD activity, phosphatidic acid (PA) promoted silymarin accumulation. Altering PLD activity by introducing in cultures n-butanol (nBuOH), which inhibits PA production by PLD, prevented silymarin elicitation by MeJA or Mst and also impeded its release in non-elicited cultures. Treatment with iso-, sec- or tert- butanol had no effect on silymarin production. The exogenous addition of PA reversed the inhibitory action of nBuOH, both in control and MeJA-treated cultures. These results suggest that the enzyme PLD and its product PA mediate silymarin secretion to the medium of S. marianum cultures.
水飞蓟宾是从水飞蓟宾（Silybum marianum）培养物的细胞外基质中释放出来的，其产量可以通过茉莉酸甲酯（MeJA）等诱导剂来刺激。目前尚不清楚导致这种反应的信号转导过程的顺序。本研究报道，MeJA 可增加磷脂酶 D（PLD）的活性。用蜂毒素（Mst）处理，一种 PLD 活性刺激剂，也能增强 PLD 并导致水飞蓟宾产量的大幅增加。PLD 活性产物磷酸脂（PA）的应用促进了水飞蓟宾的积累。通过在培养物中加入正丁醇（nBuOH）来改变 PLD 活性，nBuOH 抑制了 PLD 产生的 PA，从而阻止了 MeJA 或 Mst 诱导的水飞蓟宾的产生，并阻碍了未诱导培养物中其的释放。用异丁醇、仲丁醇或叔丁醇处理对水飞蓟宾的产生没有影响。PA 的外源添加逆转了 nBuOH 在对照和 MeJA 处理培养物中的抑制作用。这些结果表明，PLD 酶及其产物 PA 介导了水飞蓟宾分泌到水飞蓟宾（S. marianum）培养物的培养基中。
