Prepenetration apparatus assembly precedes and predicts the colonization patterns of arbuscular mycorrhizal fungi within the root cortex of both Medicago truncatula and Daucus carota
Prepenetration apparatus assembly precedes and predicts the colonization patterns of arbuscular mycorrhizal fungi within the root cortex of both Medicago truncatula and Daucus carota
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DOI：
10.1105/tpc.108.059014
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发表时间：
2008-05-01
期刊：
影响因子：
11.6
通讯作者：
Bonfante, Paola
中科院分区：
文献类型：
--
作者：
Genre, Andrea;Chabaud, Mireille;Bonfante, Paola
丛枝菌根（AM）是广泛分布的古老的内共生体，对植物吸收土壤养分有重要作用.我们先前已经表明，宿主根的初始真菌渗透是通过称为预渗透器（PPA）的专门细胞质组装介导的，其引导AM菌丝穿过表皮（Genre等人，2005年）。在体内共聚焦显微镜研究进行蒺藜苜蓿和胡萝卜，宿主植物与不同模式的AM殖民化，现在揭示，随后的细胞内生长的根外皮层也PPA依赖。另一方面，内根皮层定植导致丛枝发育涉及更多样和复杂的PPA相关机制。特别是在相邻的D.胡萝卜，与这种植物的细胞内根定殖策略。这些含PPA的细胞的超微结构分析揭示了强烈的膜贩运加上核扩大和重塑，典型的特征的arbusculated细胞。两者合计，这些研究结果意味着，渗透前的反应都是保守的和调制整个AM共生作为一个功能的不同阶段的真菌住宿和主机特定的模式根殖民。我们提出了一个模型，细胞内AM真菌住宿整合周围的丛枝接口的形成和功能性丛枝发育的调节。
Arbuscular mycorrhizas (AM) are widespread, ancient endosymbiotic associations that contribute significantly to soil nutrient uptake in plants. We have previously shown that initial fungal penetration of the host root is mediated via a specialized cytoplasmic assembly called the prepenetration apparatus (PPA), which directs AM hyphae through the epidermis (Genre et al., 2005). In vivo confocal microscopy studies performed on Medicago truncatula and Daucus carota, host plants with different patterns of AM colonization, now reveal that subsequent intracellular growth across the root outer cortex is also PPA dependent. On the other hand, inner root cortical colonization leading to arbuscule development involves more varied and complex PPA-related mechanisms. In particular, a striking alignment of polarized PPAs can be observed in adjacent inner cortical cells of D. carota, correlating with the intracellular root colonization strategy of this plant. Ultrastructural analysis of these PPA-containing cells reveals intense membrane trafficking coupled with nuclear enlargement and remodeling, typical features of arbusculated cells. Taken together, these findings imply that prepenetration responses are both conserved and modulated throughout the AM symbiosis as a function of the different stages of fungal accommodation and the host-specific pattern of root colonization. We propose a model for intracellular AM fungal accommodation integrating peri-arbuscular interface formation and the regulation of functional arbuscule development.