广西典型高砷区蜈蚣草根围丛枝菌根真菌多样性研究

丛枝菌根真菌(arbuscular mycorrhizal fungi,AM真菌)在提高超富集植物蜈蚣草(Pteris vittata L.)修复砷污染土壤方面具有巨大的应用潜力,但是中国砷污染地区的AM真菌的分布和资源调查还不够全面。为探明砷污染地区AM真菌的多样性状况,采用野外调查和室内分析相结合的方法,通过形态学特征分离鉴定AM真菌种属,对广西南丹县高砷矿区及周边地区蜈蚣草根围土壤中AM真菌的多样性及群落组成进行调查研究。结果表明,不同程度砷污染土壤中生长的蜈蚣草均能被AM真菌侵染,随着砷浓度的增加物种多样性总体呈下降趋势。无污染土壤中的AM真菌侵染率和孢子密度主要受土壤磷和海拔的影响。低磷促进孢子萌发和菌丝生长,从而提高侵染率,而海拔升高会导致孢子密度降低。但随着土壤砷污染水平的增加,砷浓度逐渐成为主要影响因子,使侵染率上升,孢子密度下降。孢子密度和物种丰富的变化趋势一致。鉴定出4属10种AM真菌,其中7种属于球囊霉属(Glomus),近明囊霉属(Claroideoglomus)、管柄囊霉属(Funneliformis)和盾巨孢囊霉属(Scutellospora)各1种,球囊霉属是该调查区域的优势属。AM真菌孢子的形态直接影响其适应能力,颜色深、表面网纹间隔致密的AM真菌抗逆性更好,近明球囊霉(C.claroidem)、团集球囊霉(G.glomerulatum)和地表球囊霉(G.versiforme)等适应性较强的菌种分离频度达到了100%,相对丰度也较高。研究结果将会对砷污染地区AM真菌优良菌株的筛选及超富集植物-AM真菌联合修复重金属污染土壤提供有益的指导。

The Diversity of Arbuscular Mycorrhizal Fungi in Rhizophere of Pteris Vittata L. Around the High as Areas in Guangxi

Arbuscular mycorrhizal fungi(AM fungi)has great potential for improving As extraction efficiency of Pteris Vittata L.applied to As contaminated soil remediation,but little is known about the distribution and resource of AM fungi in high-As areas.We investigated the diversity and community composition of AM fungi in rhizophere of P.Vittata grown on As polluted sites with different As contaminated levels.It was found that all of the investigated plants of P.Vittata were infected by AM fungi.With the increase of soil As content,the mycorrhizal infection rate decreased first and then increased,while the species diversity of AM fungi showed a downward trend.The infection rate and spore density of AM fungi in non polluted soil were mainly affected by soil phosphorus and altitude.Low phosphorus promoted spore germination and mycelial growth,which increased the infection rate,while the increase of altitude would lead to the decrease of spore density.However,with the increase of As pollution level in soil,As concentration gradually became the main influencing factor,which increased the infection rate and decreased the spore density.The variation trend of spore density and species richness was consistent.A total of 10 species belonging to 4 genera of AM fungi were isolated and identified,including 7 species of Glomus,1 species of Claroideoglomus,1 pecies of Funneliformis,and 1 pecies of Scutellospora.Glomus was the dominant genus of AM fungi in the 5 investigated sites.The AM fungi strains with deep color and dense surface reticular spacing,such as C.claroidem,G.glomerulatum and G.versiforme,have better resistance to adverse environment and achieved 100%isolation frequency and relatively high relative abundance.The results will provide a theoretical basis for further screening of AM excellent strains and application of AM fungi on remediation of As polluted soils.