香蕉枯萎病菌侵染香蕉根系的组织学过程

Histological observation of banana root infected by Fusarium oxysporum f.sp. cubense

为探明香蕉枯萎病菌侵染香蕉根系的过程,利用绿色荧光蛋白标记的香蕉枯萎病菌4号生理小种(Fusarium oxyspo-rum f.sp. cubense race 4 tagged with green fluorescent protein,GFP-FOC4),接种香蕉根系以观察病原菌侵染香蕉根系的组织学过程。结果表明,接种1 d后病原菌以菌丝体、大型分生孢子和小型分生孢子的形式附着于根系表皮细胞,优先沿细胞胞间层生长。接种7 d后,观察到病原菌以菌丝体、大型分生孢子和小型分生孢子的形式直接侵染维管束,在维管束内以两种方式扩展繁殖,一种在维管束内横向扩展,菌丝体随机分支,逐步形成网状分布;另一种是菌丝体在维管束内纵向生长,倾向于呈束状沿维管束单侧生长繁殖,形成大量菌丝体。本研究首次从组织病理学的角度观察并分析了GFP-FOC4侵染香蕉根系的过程,为研究香蕉枯萎病菌的致病过程机理提供参考。

In order to observe the infection process of Fusarium oxysporum f.sp.cubense race 4（FOC4） in banana root,the green fluorescent protein（GFP） was transformed into FOC4.The histopathological observation was carried out following the inoculation of banana root with GFP-FOC4.The results showed that the hyphae and a few germinated conidia（including macroconidia and microconidia）of GFP-FOC4 attached the banana root epidermis cells at one day after inoculation.The preferential colonization sites on the root surface were observed,which were the grooves along the junctions of adjacent epidermal cells.Further observation showed that hyphae,macroconidia and microconidia of GFP-FOC4 appeared in xylem vessels of the banana root at seven days after inoculation.The massive infectious hyphae of the fungal pathogen was observed extensively in the xylem vessels of banana root.This is the first report on histological observation of the infection process of FOC4 in banana root.The results obtained play an important role in exploring the pathogenic mechanism of this pathogen.