Rice Blast Fungus (Magnaporthe oryzae) Infects Arabidopsis via a Mechanism Distinct from That Required for the Infection of Rice
Rice Blast Fungus (Magnaporthe oryzae) Infects Arabidopsis via a Mechanism Distinct from That Required for the Infection of Rice
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DOI：
10.1104/pp.108.129536
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发表时间：
2009-01-01
期刊：
影响因子：
7.4
通讯作者：
Lee, Yong-Hwan
中科院分区：
文献类型：
--
作者：
Park, Ju-Young;Jin, Jianming;Lee, Yong-Hwan
稻瘟病菌是引起水稻稻瘟病的一种半活体营养型病原真菌。虽然M.该菌作为一个整体侵染单子叶植物的寄主范围很广，尚未有双子叶植物作为寄主的报道。结果表明，两株水稻致病菌M. KJ 201和70-15与16种生态型的拟南芥（Arabidopsis thaliana）存在差异互作。菌株KJ 201以不同程度的毒力感染所有生态型，而菌株70-15在某些生态型中不引起症状。在高度感病的生态型，小褪绿病变出现在感染叶片接种后3天内，随后扩大整个受影响的叶片。该真菌在敏感生态型中产生孢子，但在抗性生态型中不产生孢子。从坏死病变中恢复的真菌培养物在健康植物中引起相同的症状，满足科赫假设。组织化学分析表明，真菌感染导致活性氧的积累和最终的细胞死亡。与水稻的侵染过程相似，该真菌在拟南芥中分化形成附着胞，直接侵入叶表。然而，在拟南芥中的致病机制似乎不同于在水稻中的致病性;在水稻中致病性所必需的三个真菌基因在引起拟南芥中的疾病症状中仅发挥有限的作用，并且真菌似乎通过分泌植物毒性化合物（包括9，12-十八碳二烯酸）作为坏死营养体在拟南芥中定殖。PR-1和PDF1.2的表达被诱导响应于真菌感染，这表明水杨酸和茉莉酸/乙烯依赖性信号通路的激活。然而，这些信号通路在M.目前还不清楚。结合M.因此，这个新建立的病理系统允许在两个研究充分的模式植物的发病机制和宿主防御的分子和细胞机制进行比较。
Magnaporthe oryzae is a hemibiotrophic fungal pathogen that causes rice (Oryza sativa) blast. Although M. oryzae as a whole infects a wide variety of monocotyledonous hosts, no dicotyledonous plant has been reported as a host. We found that two rice pathogenic strains of M. oryzae, KJ201 and 70-15, interacted differentially with 16 ecotypes of Arabidopsis (Arabidopsis thaliana). Strain KJ201 infected all ecotypes with varying degrees of virulence, whereas strain 70-15 caused no symptoms in certain ecotypes. In highly susceptible ecotypes, small chlorotic lesions appeared on infected leaves within 3 d after inoculation and subsequently expanded across the affected leaves. The fungus produced spores in susceptible ecotypes but not in resistant ecotypes. Fungal cultures recovered from necrotic lesions caused the same symptoms in healthy plants, satisfying Koch's postulates. Histochemical analyses showed that infection by the fungus caused an accumulation of reactive oxygen species and eventual cell death. Similar to the infection process in rice, the fungus differentiated to form appressorium and directly penetrated the leaf surface in Arabidopsis. However, the pathogenic mechanism in Arabidopsis appears distinct from that in rice; three fungal genes essential for pathogenicity in rice played only limited roles in causing disease symptoms in Arabidopsis, and the fungus seems to colonize Arabidopsis as a necrotroph through the secretion of phytotoxic compounds, including 9,12-octadecadienoic acid. Expression of PR-1 and PDF1.2 was induced in response to infection by the fungus, suggesting the activation of salicylic acid- and jasmonic acid/ethylene-dependent signaling pathways. However, the roles of these signaling pathways in defense against M. oryzae remain unclear. In combination with the wealth of genetic and genomic resources available for M. oryzae, this newly established pathosystem allows comparison of the molecular and cellular mechanisms underlying pathogenesis and host defense in two well-studied model plants.