Infection of wheat spikes by Fusarium avenaceum and alterations of cell wall components in the infected tissue
Infection of wheat spikes by Fusarium avenaceum and alterations of cell wall components in the infected tissue
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DOI：
10.1007/s10658-004-1983-9
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发表时间：
2005-01-01
影响因子：
1.8
通讯作者：
Buchenauer, H
中科院分区：
文献类型：
--
作者：
Kang, ZS;Zingen-Sell, I;Buchenauer, H
应用电镜和细胞化学标记技术，研究了燕麦镰刀菌（Fusarium avenaceum）在小麦生长期（GS）65（开花中期）喷雾接种后，对小麦穗部的侵染过程和侵染组织细胞壁成分的变化。大分生孢子在接种后6-12 h在寄主表面萌发，萌发时具1 ~数个芽管。芽管并不立即穿透寄主组织，而是在寄主表面延伸和分支。接种后3-4天（dai），颖片、外稃和内稃背面的菌丝生长很少，没有观察到直接穿透小穗的外表面。在颖片、外稃、内稃和子房的内表面上形成密集的菌丝网络。侵染菌丝仅在颖片、外稃、内稃和子房上部的近轴面侵入寄主组织36 h。真菌穿透角质层，菌丝在表皮下或表皮壁层之间延伸。表皮下生长阶段，其次是穿透表皮壁，菌丝迅速蔓延间和细胞内的颖片，外稃，内稃和子房。在麦穗坏死营养型定殖阶段，寄主组织发生了一系列变化，如细胞质和细胞器的退化、寄主细胞的崩解和寄主细胞壁的解体。免疫金标记技术表明，穗组织的细胞壁含有减少量的纤维素，木聚糖和果胶细胞间菌丝或感染钉附近相比，健康的宿主组织的墙壁。这些研究表明，F.燕麦促进小麦穗的快速定殖。这是由于该菌对小穗组织远轴面和近轴面的不同侵入特性以及在寄主组织上的两种不同定殖策略所致。avenaceum进行了讨论。研究了F. avenaceum在小麦小穗中的分布与F. culmorum和F.禾谷镰刀菌（F. graminearum）产生的真菌毒素，avenaceum与后两种镰刀菌不同。
The infection process of Fusarium avenaceum on wheat spikes and the alteration of cell wall components in the infected host tissue were examined by means of electron microscopy and cytochemical labelling techniques following spray inoculation at growth stage (GS) 65 (mid-flowering). Macroconidia of the pathogen germinated with one to several germ-tubes 6-12 h after inoculation (hai) on host surfaces. The germ-tubes did not penetrate host tissues immediately, but extended and branched on the host surfaces. Hyphal growth on abaxial surfaces of the glume, lemma and palea was scanty 3-4 days after inoculation (dai) and no direct penetration of the outer surfaces of the spikelet was observed. Dense mycelial networks formed on the inner surfaces of the glume, lemma, palea and ovary 36-48 hai. Penetration of the host tissue occurred 36 hai by infection hyphae only on the adaxial surfaces of the glume, lemma, palea and upper part of ovary. The fungus penetrated the cuticle and hyphae extended subcuticularly or between the epidermal wall layers. The subcuticular growth phase was followed by penetration of the epidermal wall, and hyphae spread rapidly inter- and intracellularly in the glume, lemma, palea and ovary. During this necrotrophic colonization phase of the wheat spike, a series of alterations occurred in the host tissues, such as degeneration of cytoplasm and cell organelles, collapse of host cells and disintegration of host cell walls. Immunogold labelling techniques showed that cell walls of spike tissues contained reduced amounts of cellulose, xylan and pectin near intercellular hyphae or infection pegs compared to walls of healthy host tissues. These studies suggest that cell wall degrading enzymes produced by F. avenaceum facilitated rapid colonization of wheat spikes. The different penetration properties of abaxial and adaxial surfaces of the spikelet tissues as well as the two distinct colonization strategies of host tissues by F. avenaceum are discussed. The penetration and colonization behaviour of F. avenaceum in wheat spikelets resembled that of F. culmorum and F. graminearum, although mycotoxins produced by F. avenaceum differed from those of the latter two Fusarium species.