Department of Biotechnology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.
Department of Data Analysis and Mathematical Modelling, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.
Mol Plant Pathol. 2020 Dec;21(12):1634-1646. doi: 10.1111/mpp.13003. Epub 2020 Oct 20.
Hirschmanniella oryzae is one of the most devastating nematodes on rice, leading to substantial yield losses. Effector proteins aid the nematode during the infection process by subduing plant defence responses. In this research we characterized two potential H. oryzae effector proteins, chorismate mutase (HoCM) and isochorismatase (HoICM), and investigated their enzymatic activity and their role in plant immunity. Both HoCM and HoICM proved to be enzymatically active in complementation tests in mutant Escherichia coli strains. Infection success by the migratory nematode H. oryzae was significantly higher in transgenic rice lines constitutively expressing HoCM or HoICM. Expression of HoCM, but not HoICM, increased rice susceptibility against the sedentary nematode Meloidogyne graminicola also. Transcriptome and metabolome analyses indicated reductions in secondary metabolites in the transgenic rice plants expressing the potential nematode effectors. The results presented here demonstrate that both HoCM and HoICM suppress the host immune system and that this may be accomplished by lowering secondary metabolite levels in the plant.
稻干尖线虫是危害水稻的最严重的线虫之一，会导致大量的产量损失。效应蛋白在感染过程中通过抑制植物防御反应来帮助线虫。在这项研究中，我们鉴定了两个潜在的稻干尖线虫效应蛋白，分支酸变位酶（HoCM）和异分支酸变位酶（HoICM），并研究了它们的酶活性及其在植物免疫中的作用。在突变大肠杆菌菌株的互补测试中，HoCM 和 HoICM 均被证明具有酶活性。在组成型表达 HoCM 或 HoICM 的转基因水稻品系中，迁徙性线虫稻干尖线虫的侵染成功率显著提高。HoCM 的表达，而不是 HoICM 的表达，也增加了水稻对定殖性线虫麦根结线虫的易感性。转录组和代谢组分析表明，表达潜在线虫效应蛋白的转基因水稻植物中的次生代谢物减少。本研究结果表明，HoCM 和 HoICM 均能抑制宿主的免疫系统，这可能是通过降低植物中的次生代谢物水平来实现的。
