Gao Xiquan, Brodhagen Marion, Isakeit Tom, Brown Sigal Horowitz, Göbel Cornelia, Betran Javier, Feussner Ivo, Keller Nancy P, Kolomiets Michael V
Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843-2132, USA.
Mol Plant Microbe Interact. 2009 Feb;22(2):222-31. doi: 10.1094/MPMI-22-2-0222.
Plant and fungal lipoxygenases (LOX) catalyze the oxidation of polyunsaturated fatty acids, creating fatty-acid hydroperoxides (oxylipins). Fungal oxylipins are required for normal fungal development and secondary metabolism, and plant host-derived oxylipins interfere with these processes in fungi, presumably by signal mimicry. The maize LOX gene ZmLOX3 has been implicated previously in seed-Aspergillus interactions, so we tested the interactions of a mutant maize line (lox3-4, in which ZmLOX3 is disrupted) with the mycotoxigenic seed-infecting fungi Aspergillus flavus and Aspergillus nidulans. The lox3-4 mutant was more susceptible than wild-type maize to both Aspergillus species. All strains of A. flavus and A. nidulans produced more conidia and aflatoxin (or the precursor sterigmatocystin) on lox3-4 kernels than on wild-type kernels, in vitro and under field conditions. Although oxylipins did not differ detectably between A. flavus-infected kernels of the lox3-4 and wild-type (WT) maize, oxylipin precursors (free fatty acids) and a downstream metabolite (jasmonic acid) accumulated to greater levels in lox3-4 than in WT kernels. The increased resistance of the lox3-4 mutant to other fungal pathogens (Fusarium, Colletotrichum, Cochliobolus, and Exserohilum spp.) is in sharp contrast to results described herein for Aspergillus spp., suggesting that outcomes of LOX-governed host-pathogen interactions are pathogen-specific.
植物和真菌脂氧合酶（LOX）催化多不饱和脂肪酸的氧化，生成脂肪酸氢过氧化物（氧脂素）。真菌氧脂素是真菌正常发育和次级代谢所必需的，而植物宿主衍生的氧脂素可能通过信号模拟干扰真菌的这些过程。玉米LOX基因ZmLOX3先前已被证明参与种子与曲霉菌的相互作用，因此我们测试了一个突变玉米品系（lox3-4，其中ZmLOX3被破坏）与产毒的种子感染真菌黄曲霉和构巢曲霉的相互作用。lox3-4突变体比野生型玉米对这两种曲霉菌更敏感。在体外和田间条件下，所有黄曲霉和构巢曲霉菌株在lox3-4玉米粒上产生的分生孢子和黄曲霉毒素（或前体柄曲霉素）都比在野生型玉米粒上多。虽然lox3-4和野生型（WT）玉米受黄曲霉感染的玉米粒中的氧脂素没有明显差异，但lox3-4玉米粒中氧脂素前体（游离脂肪酸）和下游代谢物（茉莉酸）的积累水平高于WT玉米粒。lox3-4突变体对其他真菌病原体（镰刀菌、炭疽菌、旋孢腔菌和突脐孢菌属）的抗性增加与本文所述的曲霉菌属的结果形成鲜明对比，表明LOX调控的宿主-病原体相互作用的结果具有病原体特异性。
