白皮松天然林外生菌根土壤繁殖体库

Soil propagule bank of ectomycorrhizal fungi in natural forest of Pinus bungeana

为更好地恢复和保存白皮松天然林,在陕西省白皮松残存林地采集根际土壤,采用幼苗检测法获取土壤外生菌根真菌繁殖体,用形态观察分类与ITS-PCR-sequencing相结合的方法进行菌根鉴定,研究白皮松林地外生菌根真菌土壤繁殖体库的组成.结果表明:在白皮松幼苗菌根中共获得73个特异性序列;按照97%的相似度阈值,将序列划分为12个可操作分类单元(OTUs);稀疏曲线分析表明,本研究基本获得了白皮松土壤外生菌根繁殖体库的多样性.常见种有土生空团菌、Tomentella sp.、Tuber sp.等.出现频率最高的一个OTU(80%)与已知种类相似度较低(75%),说明其可能是一个新的菌根菌种类.白皮松残存天然林地的外生菌根繁殖体库中具有其他松科植物土壤繁殖体库常见的种类,但是频率最高的种类未能鉴定到已知属或科,说明白皮松菌根繁殖体库具有其宿主特异性.这种群落特异构成也说明研究和利用白皮松土壤外生菌根真菌繁殖体库具有特殊性和重要性.

To conserve and restore the forest of Pinu bungeana,we investigated the soil propagule bank of ectomycorrhizal（ECM） fungi in a severely disturbed natural forest of P.bungeana in Shaanxi Province,China.We used a seedling-bioassay method to bait the ECM fungal propagules in the soils collected from the forest site.ECM was identified by combining morph typing with ITSPCR-sequencing.We obtained 73 unique sequences from the ECM associated with P.bungeana seedlings,and assigned them into 12 ECM fungal OTUs at the threshold of 97% based on the sequence similarity.Rarefaction curve displayed almost all ECM fungi in the propagule bank were detected.The most frequent OTU（80%） showed poor similarity（75%） with existing sequences in the online database,which suggested it might be a new species.Cenococcum geophilum,Tomentella sp.,Tuber sp.were common species in the propagule bank.Although C.geophilum and Tomentella sp.were frequently detected in other soil propagule banks of pine forest,the most frequent OTU was not assigned to known genus or family,which indicated the host-specif of ECM propagule banks associated with P.bungeana.This result confirmed the importance of the special ECM propagule banks associated with P.bungeana for natural forest restoration.