Abstract

Ganoderma lucidum, which contains numerous biologically active compounds, is known worldwide as a medicinal basidiomycete. Because of its application for the prevention and treatment of various diseases, most of artificially cultivated G. lucidum is output to many countries as food, tea, and dietary supplements for further processing. Methyl jasmonate (MeJA) has been reported as a compound that can induce ganoderic acid (GA) biosynthesis, an important secondary metabolite of G. lucidum. Herein, MeJA was found to increase the intracellular level of nitric oxide (NO). In addition, upregulation of GA biosynthesis in the presence of MeJA was abolished when NO was depleted from the culture. This result demonstrated that MeJA-regulated GA biosynthesis might occur via NO signaling. To elucidate the underlying mechanism, we used gene-silenced strains of nitrate reductase (NR) and the inhibitor of NR to illustrate the role of NO in MeJA induction. The results indicated that the increase in GA biosynthesis induced by MeJA was activated by NR-generated NO. Furthermore, the findings indicated that the reduction of NO could induce GA levels in the control group, but NO could also activate GA biosynthesis upon MeJA treatment. Further results indicated that NR silencing reversed the increased enzymatic activity of NOX to generate ROS due to MeJA induction. Importantly, our results highlight the NR-generated NO functions in signaling crosstalk between reactive oxygen species and MeJA. These results provide a good opportunity to determine the potential pathway linking NO to the ROS signaling pathway in fungi treated with MeJA.

Key points

• MeJA increased the intracellular level of nitric oxide (NO) in G. lucidum.

• The increase in GA biosynthesis induced by MeJA is activated by NR-generated NO.

• NO acts as a signaling molecule between reactive oxygen species (ROS) and MeJA.

中文翻译：

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硝酸还原酶依赖性一氧化氮在灵芝中由MeJA诱导的灵芝酸生物合成中起关键作用

摘要

灵芝，其中包含许多生物活性化合物，在世界范围内被称为药用担子菌。由于其在各种疾病的预防和治疗中的应用，大部分人工栽培的灵芝都作为食品，茶和膳食补充剂输出到许多国家，以进行进一步加工。茉莉酸甲酯（MeJA）已被报道为一种化合物，可以诱导灵芝酸（GA）的生物合成，灵芝的重要次生代谢产物。。在本文中，发现MeJA增加细胞内一氧化氮（NO）的水平。另外，当从培养物中耗尽NO时，消除了在MeJA存在下GA生物合成的上调。该结果表明MeJA调节的GA生物合成可能通过NO信号传导发生。为了阐明其潜在机制，我们使用了基因沉默的硝酸还原酶（NR）菌株和NR抑制剂来说明NO在MeJA诱导中的作用。结果表明，MeJA诱导的GA生物合成的增加被NR生成的NO激活。此外，研究结果表明，NO的降低可以诱导对照组的GA水平，但NO也可以在MeJA处理后激活GA生物合成。进一步的结果表明，由于MeJA诱导，NR沉默逆转了NOX增加的酶促活性以生成ROS。重要的是，我们的结果强调了NR生成的NO在活性氧与MeJA之间串扰的信号传递中的作用。这些结果提供了一个很好的机会，可以确定在用MeJA处理的真菌中将NO与ROS信号通路连接的潜在途径。

关键点

• MeJA增加了灵芝中一氧化氮（NO）的细胞内水平。

• MeJA诱导的GA生物合成的增加被NR生成的NO激活。

• NO充当活性氧（ROS）和MeJA之间的信号分子。