Temasek Life Sciences Laboratory, Singapore.
1] Department of Biological Sciences, National University of Singapore, Singapore. [2] Singapore Centre for Environmental Life Sciences Engineering, Singapore. [3] NUS Environmental Research Institute, National University of Singapore, Singapore.
Nat Chem Biol. 2015 Sep;11(9):733-40. doi: 10.1038/nchembio.1885. Epub 2015 Aug 10.
Distinct modifications fine-tune the activity of jasmonic acid (JA) in regulating plant growth and immunity. Hydroxylated JA (12OH-JA) promotes flower and tuber development but prevents induction of JA signaling, plant defense or both. However, biosynthesis of 12OH-JA has remained elusive. We report here an antibiotic biosynthesis monooxygenase (Abm) that converts endogenous free JA into 12OH-JA in the model rice blast fungus Magnaporthe oryzae. Such fungal 12OH-JA is secreted during host penetration and helps evade the defense response. Loss of Abm in M. oryzae led to accumulation of methyl JA (MeJA), which induces host defense and blocks invasive growth. Exogenously added 12OH-JA markedly attenuated abmΔ-induced immunity in rice. Notably, Abm itself is secreted after invasion and most likely converts plant JA into 12OH-JA to facilitate host colonization. This study sheds light on the chemical arms race during plant-pathogen interaction, reveals Abm as an antifungal target and outlines a synthetic strategy for transformation of a versatile small-molecule phytohormone.
不同的修饰微调了茉莉酸 (JA) 在调节植物生长和免疫中的活性。羟基化的 JA (12OH-JA) 促进花和块茎的发育，但阻止了 JA 信号转导、植物防御或两者的诱导。然而，12OH-JA 的生物合成仍然难以捉摸。我们在这里报告了一种抗生素生物合成单加氧酶 (Abm)，它可以将内源性游离 JA 转化为模式稻瘟病菌稻瘟病菌中的 12OH-JA。这种真菌 12OH-JA 在宿主穿透过程中被分泌出来，有助于逃避防御反应。稻瘟病菌中 Abm 的缺失导致甲基 JA (MeJA) 的积累，从而诱导宿主防御并阻止侵袭性生长。外源添加的 12OH-JA 显著减弱了 abmΔ 诱导的水稻免疫。值得注意的是，Abm 本身在入侵后被分泌出来，很可能将植物 JA 转化为 12OH-JA，以促进宿主定植。这项研究揭示了植物-病原体相互作用过程中的化学军备竞赛，揭示了 Abm 作为一种抗真菌靶标，并概述了一种将多功能小分子植物激素转化为合成策略。
