高磷土壤中丛枝菌根真菌的分离鉴定

【背景】丛枝菌根(arbuscular mycorrhiza，AM)真菌具有广泛的寄主范围、环境适应性和优良的植物促生能力。然而，土壤的高磷水平严重抑制了AM真菌生长及AM形成。【目的】分离鉴定出耐较高有效磷含量的华南土著AM真菌菌株，为菌根学研究工作提供新颖材料。【方法】采用经典形态学和分子系统学方法鉴定高磷土壤中AM真菌。【结果】从有效磷含量为53-131 (平均值±标准差为88.2±17.6) mg/kg的根区土壤中鉴定出7属25种AM真菌，包括无梗囊霉属(Acaulospora) 12种、球囊霉属(Glomus) 7种、隔球囊霉属(Septoglomus) 2种、近明球囊霉属(Claroideoglomus) 1种、根孢囊霉属(Rhizophagus) 1种、硬囊霉属(Sclerocystis) 1种和类球囊霉属(Paraglomus) 1种，其中幼套近明球囊霉(Claroideoglomus etunicatum)和蜜色无梗囊霉(Acaulospora mellea)是优势种。在(87.7±8.0) mg/kg的高磷水平下，AM真菌仍能形成丛枝和泡囊。但当有效磷含量达到(99.7±1.2) mg/kg时，菌根侵染率和丛枝丰度显著下降，但仍能够形成泡囊。【结论】从广州市南沙区有效磷含量为(88.2±17.6) mg/kg的耕地植物根区土壤中，鉴定出具有耐高磷潜力的7属25种AM真菌，幼套近明球囊霉和蜜色无梗囊霉等分离株可作为后续高磷抑制机制解析及耐高磷AM真菌菌剂研发工作的试验菌株。

Isolation and identification of arbuscular mycorrhizal fungi from high phosphate soils

Background] Arbuscular mycorrhizal (AM) fungi have a wide range of host species, environmental adaptation and remarkable plant growth-promoting capability. However, high phosphate level in soils has seriously inhibited the growth of AM fungi and the AM formation. Objective] This study aimed to isolate and identify indigenous AM fungal strains resistant to high phosphate in south China, and to provide novel materials for mycorrhiza research. Methods] The AM fungi from high phosphate soils were identified by classical morphology and molecular systematics. Results] Twenty-five AM fungi species belonging to 7 genera were identified from root-zone soils with the available phosphorus concentration of 53-131 (88.2±17.6 as average±SD) mg/kg, including 12 species in Acaulospora, 7 in Glomus, 2 in Septoglomus, 1 in Claroideoglomus, 1 in Rhizophagus, 1 in Sclerocystis and 1 in Paraglomus, among which Claroideoglomus etunicatum and Acaulospora mellea were dominant. At the high phosphate level of (87.7±8.0) mg/kg, AM fungi still formed arbuscules and vesicles. However, when the phosphate level reached (99.7±1.2) mg/kg, total colonization frequency and arbuscular abundance were significantly decreased in mycorrhizal roots, but vesicles were still be formed. Conclusion] In this study, 25 AM fungi belonging to 7 genera that might be resistant to high phosphate concentration were identified from root-zone soils containing (88.2±17.6) mg/kg phosphate in cultivated land in Nansha district of Guangzhou city. The isolated strains such as C. etunicatum and A. mellea could be used as experimental strains in further studies on the high phosphate inhibition and the production of high-quality AM fungal inocula resistant to high phosphate.