9种蕨类植物丛枝菌根真菌侵染的结构观察

蕨类植物普遍能与丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)形成稳定的共生关系,并显著增强其获取养分和抵抗环境胁迫的能力,为了明晰AMF在不同蕨类植物体内的侵染特征,该研究对广东封开黑石顶自然保护区内的蕨类植物进行野外调查取样,并利用光镜和透射电镜对蕨类植物—AMF共生体的显微和亚显微结构进行观察分析,以明确不同蕨类植物与AMF的共生特征,从而进一步保护和开发利用华南地区蕨类植物资源。结果表明:(1)研究区的AMF对不同蕨类植物的侵染形式均以菌丝为主,而丛枝侵染率最低;不同蕨类植物之间的AMF总侵染率存在显著差异,其中团叶鳞始蕨(56.03%)均显著高于其他物种(P<0.05)。(2)显微观察显示,菌丝是AMF定殖于各种蕨类植物根系中最常见的形式,在9种蕨类植物根皮层细胞中均有发现,但不存在于中柱细胞。(3)观察发现,AMF菌丝主要由2~3层厚薄不一的薄壁细胞组成,多呈椭圆形和扁平形状。(4)AMF菌丝及泡囊中包含许多小液泡和脂质类物质,这可能是菌根结构储存能量的重要方式。研究认为,陆地生态系统中AMF对蕨类植物普遍具有侵染的能力,但其在不同蕨类植物根系中的赋存形式具有显著差异,这可能归因于植物自身生理特征以及生境条件的相互作用。

Structural Observation on Arbuscular Mycorrhizal Fungal Infection of Nine Species of Pteridophytes

Pteridophytes can establish stable symbiotic relationship with arbuscular mycorrhizal fungi (AMF), and significantly enhance their ability to obtain nutrients and resistance to environmental stress. To clarify the AMF colonization characteristics of different pteridophytes, a field survey and sampling of pteridophytes were conducted in Fengkai Heishiding Nature Reserve, Guangdong province. Furthermore, the microscopic and submicroscopic structures of pteridophytes-AMF symbionts were observed and analyzed by light microscope and transmission electron microscope, so as to illustrate the symbiosis characteristics between them. This study can provide valuable information for protecting and exploiting the resources of pteridophytes in South China. The results show that: (1) Hypha was the main infection form, but with the lowest infection rate of arbuscule among different pteridophytes. There were significant differences in the total AMF colonization rate among different pteridophytes. The top three highest colonization rate of AMF was Selaginella japonicum, Lepidopteris sclerotifolia and Pteris chinense, which was significantly higher than other species (P < 0.05). (2) Microstructures observation showed that hypha colonization was the main form of AMF colonization in the roots of all pteridophytes. Hypha could be found in the root cortex cells of all 9 pteridophytes, but not in the stele cells. (3) The hypha of AMF was composed by 2 to 3 layers of thin-walled cells with different thicknesses and shapes (i.e., oval and tabular). (4) AMF hypha and vesicles contained many vacuoles and lipids, which may be regarded as an important pathway for mycorrhiza to store energy. According to this study, we confirmed the widespread colonization of AMF in pteridophytes in terrestrial ecosystems. However, our study also found that the present forms of AMF in different root cells of pteridophytes were significantly different, probably due to plant physiological characteristics and interaction among habitat conditions.