入侵植物五爪金龙根系深色有隔内生真菌的侵染特征

Colonization characteristics of dark septate endophytes in roots of invasive Ipomoea cairica

深色有隔内生真菌(DSE)广泛侵染华南地区外来入侵植物五爪金龙。显微观察发现五爪金龙根系具有大量的泡囊,其最显著的特征是大量脂质的富集和被分解成小脂质体,并通过透明或深色菌丝转移,说明了五爪金龙和DSE之间进行碳转移。富含脂质的泡囊可产生透明菌丝和自我复制,说明泡囊具有繁殖功能。富含脂质的泡囊和透明菌丝等非典型结构没有可分辨的或具透明的细胞壁,是活跃的真菌结构。透明菌丝和富含脂质的泡囊主要定殖在生理活性强的根组织中。深色有隔菌丝和微菌核是DSE的典型结构,主要定殖在相对不活跃的根组织中。DSE定殖于五爪金龙根的维管柱、皮层、表皮细胞和表面,同时延伸到土壤,在宿主植物和土壤之间形成连续的系统的真菌网络。根据DSE的多态性质、庞大的真菌网络和脂质的富集及其分布,探讨了DSE和入侵植物五爪金龙潜在的互惠共生关系。

Dark septate endophytes(DSE)widely colonize invasive Ipomoea cairica in southern China.It was observed under light microscope that I.cairica roots were colonized by a large number of lipid-filled vesicles,and the most striking feature was that a great quantity of lipids were accumulated and decomposed into small lipid bodies which were transferred through hyaline or dark hyphae,demonstrating that carbon transfer between I.cairica and DSE.Lipid-filled vesicles could produce hyaline hyphae and self-duplication,indicating that vesicles had reproductive capacity.Atypical structures such as lipid-filled vesicle and hyaline hyphae without obvious wall or with transparent wall were considered to be active fungal structures.Hyaline hyphae and lipid-filled vesicles were mainly colonized in physiologically active roots.Dark septate hyphae and microsclerotia were typical structures of DSE,mainly colonized in relatively inactive roots.DSE colonizes the vascular cylinder and cortical and epidermal cells of I.cairica and extends to the soil,indicating that DSE forms a continuous and systematic fungal network between host plant and soil.The potential symbiotic relationship between DSE and I.cairica was discussed in the light of the polymorphic nature of DSE,the huge fungal network and accumulation and distribution of lipids.