Arbuscular mycorrhizal fungi elicit a novel intracellular apparatus in Medicago truncatula root epidermal cells before infection
Arbuscular mycorrhizal fungi elicit a novel intracellular apparatus in Medicago truncatula root epidermal cells before infection
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DOI：
10.1105/tpc.105.035410
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发表时间：
2005-12-01
期刊：
影响因子：
11.6
通讯作者：
Barker, DG
中科院分区：
文献类型：
--
作者：
Genre, A;Chabaud, M;Barker, DG
丛枝菌根（AM）真菌通过宿主植物最外层根组织的渗透是根系定殖的关键步骤，最终导致这种具有重要生态意义的内共生体的建立。为了评估AM感染过程中宿主植物所发挥的作用，我们研究了在体内的蒺藜苜蓿根表皮细胞内的细胞动力学，使用绿色荧光蛋白标记的植物细胞骨架和内质网。用巨孢霉菌丝靶向根部揭示了，在感染之前，表皮细胞组装了一个具有新细胞骨架组织的瞬时细胞内结构。实时监测表明，这种结构，指定的预穿透装置（PPA），发挥了核心作用，在制定的质外体界面室，通过真菌生长时，它穿透细胞腔。PPA的重要性是由M. truncatulaDMI（不产生感染）突变体不能组装这种结构。此外，PPA在表皮中的形成可以与DMI依赖的转录激活的苜蓿早曲蛋白基因ENOD11。这些研究结果表明，宿主植物如何准备和组织AM感染的根，植物真菌的信号转导机制参与和豆科植物根毛中的根瘤菌感染的机制平行进行了讨论。
The penetration of arbuscular mycorrhizal (AM) fungi through the outermost root tissues of the host plant is a critical step in root colonization, ultimately leading to the establishment of this ecologically important endosymbiotic association. To evaluate the role played by the host plant during AM infection, we have studied in vivo cellular dynamics within Medicago truncatula root epidermal cells using green fluorescent protein labeling of both the plant cytoskeleton and the endoplasmic reticulum. Targeting roots with Gigaspora hyphae has revealed that, before infection, the epidermal cell assembles a transient intracellular structure with a novel cytoskeletal organization. Real-time monitoring suggests that this structure, designated the prepenetration apparatus (PPA), plays a central role in the elaboration of the apoplastic interface compartment through which the fungus grows when it penetrates the cell lumen. The importance of the PPA is underlined by the fact that M. truncatula dmi (for doesn't make infections) mutants fail to assemble this structure. Furthermore, PPA formation in the epidermis can be correlated with DMI-dependent transcriptional activation of the Medicago early nodulin gene ENOD11. These findings demonstrate how the host plant prepares and organizes AM infection of the root, and both the plant-fungal signaling mechanisms involved and the mechanistic parallels with Rhizobium infection in legume root hairs are discussed.