Deletion of all three MAP kinase genes results in severe defects in stress responses and pathogenesis in Fusarium graminearum.
Deletion of all three MAP kinase genes results in severe defects in stress responses and pathogenesis in Fusarium graminearum.
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所有三个 MAP 激酶基因的缺失会导致禾谷镰刀菌应激反应和发病机制的严重缺陷
DOI：
10.1007/s44154-021-00025-y
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发表时间：
2022-01-17
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丝裂原活化蛋白激酶（MAPK）级联被外部刺激激活并将信号转化为细胞变化。在许多植物病原真菌中，单个的MAPKs因其在生物或非生物胁迫的发病机制和反应中的作用而被表征。然而，所有MAPK基因缺失的突变体在丝状真菌中尚未报道。为了确定MAPK在真菌病原体中的作用，本研究在小麦赤霉病菌镰刀菌中产生并鉴定了所有三个MAPK基因的缺失突变体。Gpmk1 mgv1 Fghog1三重突变体具有严重的生长缺陷，无致病性。感染垫的形成和DON的产生存在缺陷。三突变体的分生孢子减少，产生的分生孢子往往比野生型长，间隔更多。三重突变体由于丧失雌性生育能力而在有性繁殖中受阻。缺乏任何MAPKs导致对各种非生物胁迫的敏感性增加，包括细胞壁、渗透、氧化胁迫和植物抗毒素，这可能与三重突变体在环境适应和植物感染方面的缺陷有关。该三突变体对生防菌velezensis芽孢杆菌和真菌Clonostachys rosea的敏感性也有所提高。在与白僵菌共孵育实验中，Gpmk1 mgv1 Fghog1突变体比野生型有更严重的生长限制，分生孢子萌发和胚管生长存在缺陷。在对抗试验中，该三突变体在抵御玫瑰镰刀菌的真菌活性方面存在缺陷，后者可以在突变体上生长，但不能在野生型玉米镰刀菌上生长。RNA-seq和代谢组学分析显示，MAPK三突变体改变了许多atp结合盒（ABC）和主要促进剂超家族（MFS）转运体基因的表达，以及花生四烯酸、亚油酸和α -亚麻酸代谢相关代谢物的积累。总的来说，作为真菌病原体中所有三种mapk缺失突变体的第一个研究，我们的研究结果表明，尽管mapk对生长和无性繁殖不是必需的，但Gpmk1 mgv1 Fghog1三重突变体在植物感染和有性繁殖中被阻断。它在应对各种非生物胁迫和细菌-真菌或真菌-真菌相互作用方面也存在严重缺陷。
Mitogen-activated protein kinase (MAPK) cascades are activated by external stimuli and convert signals to cellular changes. Individual MAPKs have been characterized in a number of plant pathogenic fungi for their roles in pathogenesis and responses to biotic or abiotic stresses. However, mutants deleted of all the MAPK genes have not been reported in filamentous fungi. To determine the MAPK-less effects in a fungal pathogen, in this study we generated and characterized mutants deleted of all three MAPK genes in the wheat scab fungus Fusarium graminearum. The Gpmk1 mgv1 Fghog1 triple mutants had severe growth defects and was non-pathogenic. It was defective in infection cushion formation and DON production. Conidiation was reduced in the triple mutant, which often produced elongated conidia with more septa than the wild-type conidia. The triple mutant was blocked in sexual reproduction due to the loss of female fertility. Lack of any MAPKs resulted in an increased sensitivity to various abiotic stress including cell wall, osmotic, oxidative stresses, and phytoalexins, which are likely related to the defects of the triple mutant in environmental adaptation and plant infection. The triple mutant also had increased sensitivity to the biocontrol bacterium Bacillus velezensis and fungus Clonostachys rosea. In co-incubation assays with B. velezensis, the Gpmk1 mgv1 Fghog1 mutant had more severe growth limitation than the wild type and was defective in conidium germination and germ tube growth. In confrontation assays, the triple mutant was defective in defending against mycoparasitic activities of C. rosea and the latter could grow over the mutant but not wild-type F. graminearum. RNA-seq and metabolomics analyses showed that the MAPK triple mutant was altered in the expression of many ATP-binding cassette (ABC) and major facilitator superfamily (MFS) transporter genes and the accumulation of metabolites related to arachidonic acid, linoleic acid, and alpha-linolenic acid metabolisms. Overall, as the first study on mutants deleted of all three MAPKs in fungal pathogens, our results showed that although MAPKs are not essential for growth and asexual reproduction, the Gpmk1 mgv1 Fghog1 triple mutant was blocked in plant infection and sexual reproductions. It also had severe defects in responses to various abiotic stresses and bacterial- or fungal-fungal interactions.