Effects Of Soil Type And Plant Genotype On The Community Of Arbuscular Mycorrhizal Fungi

The Karst ecosystem, with special geo-ecological environment, is fragile and sensitive:In Karst landscape, it showed mainly that soil water-holding capacity is low on the surface, soil layer is shallow and soil is discontinuous. Because of the increase in population, the Karst ecosystem degraded seriously. Although closing hillsides to facilitate afforestation could afforest degraded habitat, combining with economic benefit is necessary to realize sustainability of ecological restoration. The high benefit economical plant survived difficultly, by reason of lack of water and soil in degraded habitat. Therefore, improving seeding survival rate is the key for sustainable recovery of degraded ecological system in Karst region. Arbuscular mycorrhizal (AM) fungi are widely distributed in nature which can establish a symbiotic association with 80% terrestrial plants. They can help to activate the mineral elements in soil around the roots, promote nutrients-absorption of roots, enhance the stress tolerance of plants and improve their growth. These features AM fungi own demonstrate that AM fungi have the potential value for maintaining the stability of Karst ecosystem and vegetation recovery. However, the absence of research about the effects of soil type and plant genotype on the AM fungi in rhizosphere soil and root reduced the understanding about distribution and influencing mechanism of AM fungi, liminited artificial controls to improve sustainable recovery of degraded ecological habitat by utilizing AM fungi in Karst.In this research, three kinds of typical woody plants, the Celtis biondii Pamp, Castanopsis hystrix and Kmeria septentrionalis Dandy were selected, which are living in Mulun National Nature Reserve (Lime soil region) and Ninety Thousand Mountain National Nature Reserve (Yellow soil region) in Huanjiang County of Guangxi Zhuang Autonomous. We collected roots and rhizosphere soils respectively from these three plants. Both morphological and molecular identification methods (PCR-DGGE and RT-PCR) were used to analyze the diversity and communication structure of AM fungi in roots and rhizophere soils. The aim is to understand the key factors which lead to the distribution of AM fungi in Karst region. The main inclusions including:(1) 14 species in 2 genera were isolated from all rhizosphere soils. There were 13 species AMF which belonged to 2 genera in Lime soil, while 9 species of 2 genera in Yellow soil. There were significant differences in distribution of AM fungi in two type of soil. Glomus etunicatum, Glomus geosporum, Glomus mosseae, Glomus caledonium and Glomus claroideum were all dominant species in Lime soil, while Glomus etunicatum was the only dominant species in Yellow soil. Glomus were the dominant AM fungi in all rhizosphere soils and roots through morphology and molecular biological technique.(2) Soil type is the key factor which affected AM fungal diversity. Two factors analysis of variance showed that soil type affected AM fungi more significantly than host plant. UPGMA and RDA analysis also ignicated the similarities of AM fungi diversity lived in the same soil type are higher than which lived in the different soil type.(3) AM fungi are more suiltable for growth in the neutral soil, like Lime soil. Soil avalible phosphorus content is the key factor of nutrient to affect AM fungal diversity outside and inside the plant root. Soil total potassium is the key factor of nutrient to affect AM fungal diversity in rhizosphere soil. Soil organic carbon is the key soil factor to affect AM fungal diversity in host plant root.