毛乌素沙地樟子松外生菌根真菌多样性特征

【背景】外生菌根真菌(ectomycorrhizal fungi，ECMF)侵入林木根系形成外生菌根，是樟子松(Pinus sylvestris var. mongholica)适应环境变化和环境胁迫的重要途径。【目的】深入理解沙地樟子松人工林外生菌根真菌群落组成和多样性。【方法】以毛乌素沙地3个林龄(27、33和44 a)沙地樟子松人工林为研究对象，采用rDNA ITS区段PCR扩增测序方法鉴定分析沙地樟子松外生菌根真菌群落组成并计算多样性指数。【结果】毛乌素沙地樟子松共获得56个外生菌根真菌OTU，隶属于2门3纲8目15科21属，优势属为棉革菌属(Tomentella)、地孔菌属(Geopora)和阿太菌属(Amphinema)。27 a人工林外生菌根真菌丰富度指数最高，33 a人工林ECMF的α多样性指数最高，但不同林龄之间不存在显著差异(P>0.05)。不同林龄沙地樟子松ECMF群落组成存在差异，地孔菌属、棉革菌属、Delastria和Mallocybe的动态变化是造成群落组成差异的主要原因。【结论】毛乌素沙地樟子松人工林外生菌根真菌群落组成较为丰富，该研究区的群落组成可能比多样性更能体现外生菌根真菌群落随林龄的动态变化，伴随着林木的生长成熟，部分功能性外生菌根真菌的动态变化可能与沙地樟子松人工林退化存在密切联系，有待进一步研究。

Diversity characteristics of ectomycorrhizal fungi associated with Pinus sylvestris var. mongolica in the Mu Us sandy land

Background] Ectomycorrhiza is a symbiosis between ectomycorrhizal fungi and host plant by mycelium infection. It is an important approach for Pinus sylvestris var. mongolica to adapt environmental change and stress. Objective] To explore a deeply insight on the ectomycorrhizal fungal community composition and diversity in P. sylvestris plantations. Methods] A chronosequence of plantations (27 years old, 33 years old and 44 years old) were selected in the Mu Us Sandy Land. The community composition of ectomycorrhizal fungi associated with P. sylvestris were identified using the rDNA ITS segment PCR amplification sequencing, and diversity index was calculated. Results] The 56 obtained OTUs were assigned to 2 phyla, 3 classes, 8 orders, 15 families and 21 genera. The predominant genera were Tomentella, Geopora and Amphinema. The highest richness and alpha diversity index were detected in the 27 and 33 years old plantations, respectively. However, no significance occurred in the three plots (P>0.05). The community composition of ectomycorrhizal fungi was quite different in the plantations affected by the variations in Geopora, Tomentella, Delastria and Mallocybe. Conclusion] Ectomycorrhizal fungi associated with P. Sylvestris are abundant in the Mu Us Sandy Land. Community composition rather than diversity may indicate the dynamic changes of ectomycorrhizal fungi community with age in the Mu Us Sandy Land. With the sang ageing, the variations in functional ectomycorrhizal fungi potentially contribute to the P. sylvestris plantations degradation. This knowledge gap needs future exploration.