Responses ofQuercus sapwood to infection with the pathogenic fungus of a new wilt disease vectored by the ambrosia beetlePlatypus quercivorus
Responses ofQuercus sapwood to infection with the pathogenic fungus of a new wilt disease vectored by the ambrosia beetlePlatypus quercivorus
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栎属边材对豚草甲虫鸭嘴兽传播的新枯萎病病原真菌感染的反应
DOI：
10.1007/bf00767893
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发表时间：
2001
影响因子：
2.9
通讯作者：
K. Kuroda
中科院分区：
文献类型：
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作者：
K. Kuroda
锯缘栎和 Q.日本海沿岸广大地区夏季出现卷曲枯萎病。在出现枯萎症状之前，树木会受到豚草甲虫（Platypus quercivorus）的大规模攻击。这项研究调查了在枯萎树木中专门检测到的真菌的致病作用。这种丝状真菌，Raffaeleasp.，其分布与称为伤口心材的变色木质部区域相关，在该区域中血管功能失调。菌丝周围形成菌丝表明血管功能障碍。在变色区域，真菌菌丝从血管腔侵入活射线薄壁组织细胞。作为一种保护性反应，射线细胞将黄色物质渗入血管中，但这些物质似乎对真菌活动无效，可能是因为真菌在足够的物质积累之前就沿着甲虫的通道分散了。它应该允许边材广泛变色。真菌周围的形成层没有坏死。宿主体内的细胞学过程如下：（1）在橡树真菌的刺激下合成次生代谢产物； (2)血管内有黄色物质渗出； (3)血管和伤口心材形成的功能障碍。对于树木枯萎，真菌的致病性应通过其阻止树液流动的能力来评估。
Quercus serrataandQ. crispulawilt during the summer in wide areas along the Sea of Japan. Mass attacks of trees by an ambrosia beetle (Platypus quercivorus) are characteristic before appearance of the wilting symptoms. This study investigated the pathogenic effects of a fungus detected specifically in the wilting trees. This hyphomycete fungus,Raffaeleasp., has a distribution that correlates with the discolored xylem area called wound heartwood in which vessels are dysfunctional. Tylosis formation around the hyphae indicates vessel dysfunction. In areas with discoloration, the fungal hyphae were invading living ray parenchyma cells from the vessel lumen. As a protective reaction the ray cells exuded yellow substances into the vessels, but these substances seemed ineffective against the fungal activity, probably because the fungus disperses along the beetle's gallery before enough substance can accumulate. It should allow wide discoloration in sapwood. Cambium was not necrotic around the fungus. The cytological process in the host was as follows: (1) synthesis of secondary metabolites by the stimuli of oak fungus; (2) exudation of yellow substances into vessels; and (3) dysfunction of vessels and wound heartwood formation. In regard to wilting of trees, the pathogenicity of the fungus should be assessed by its ability to stop sap flow.