Cellulases Belonging to Glycoside Hydrolase Families 6 and 7 Contribute to the Virulence of Magnaporthe oryzae
Cellulases Belonging to Glycoside Hydrolase Families 6 and 7 Contribute to the Virulence of Magnaporthe oryzae
复制标题
DOI：
10.1094/mpmi-02-12-0043-r
复制
发表时间：
2012-09-01
影响因子：
3.5
通讯作者：
Nakayashiki, Hitoshi
中科院分区：
文献类型：
--
作者：
Ba Van Vu;Itoh, Kenji;Nakayashiki, Hitoshi
在感染后，植物病原真菌分泌一系列水解酶，可以降解宿主表皮的成分，包括蜡、角质层和细胞壁。纤维素酶，可以水解植物细胞壁中的结晶纤维素，是这些水解酶之一。在这里，我们提供了基于rnai的证据，表明属于糖基水解酶（GH）家族6和7的纤维素酶有助于植物病原真菌Magnaporthe oryzae穿透宿主表皮并进一步入侵。GH6和GH7纤维素酶可能包括M. oryzae中所有的纤维生物水解酶家族成员和一些内切葡聚糖酶。定量逆转录酶聚合酶链反应分析表明，半数以上的纤维素酶在感染过程中被高度诱导。我们使用之前报道的构建块方法构建了这些纤维素酶的敲低（KD）突变体。靶基因转录水平和纤维素酶活性在KD突变体中显著降低。与亲本菌株相比，KD突变体导致更少的病变，更少的渗透和更少的细胞感染。细胞学分析表明，高乳头形成率阻断了KD突变体对宿主细胞的入侵。这些结果表明GH6和GH7纤维素酶在M. oryzae的毒力中起作用。
Upon infection, phytopathogenic fungi secrete an array of hydrolytic enzymes that can degrade components of the host epidermis, including waxes, the cuticle, and cell walls. Cellulases, which can hydrolyze crystalline cellulose in the plant cell wall, are among these hydrolytic enzymes. Here, we provide RNAi-based evidence to show that cellulases belonging to glycosyl hydrolase (GH) families 6 and 7 contribute to the penetration of the host epidermis and further invasion by the phytopathogenic fungus Magnaporthe oryzae. The GH6 and GH7 cellulases likely include all members of the cellobiohydrolase family and some endoglucanases in M. oryzae. Quantitative reverse-transcriptase polymerase chain reaction analysis indicated that more than half of the cellulases were highly induced during infection. We constructed knock-down (KD) mutants of these cellulases using the building blocks method we reported previously. The transcript levels of the target genes and cellulase activity were considerably reduced in the KD mutants. The KD mutants resulted in fewer lesions, less penetration, and infection of fewer cells compared with the parent strain. Cytological analyses showed that a high rate of papilla formation blocked invasion of the KD mutants into host cells. These results suggest that the GH6 and GH7 cellulases play roles in the virulence of M. oryzae.