羊柴根围AM真菌群落结构和遗传多样性研究

Community composition and genetic diversity of arbuscular mycorrhizal fungi in the rhizosphere of clonal plants Hedysarum leave Maxim

为了探明受风蚀和水蚀双重影响下内蒙古荒漠地区羊柴（Hedysarum leave Maxim）根围AM真菌群落结构和遗传多样性特征,以内蒙古正蓝旗青格勒图具有代表性的梁地作为采样地点,按海拔高度在梁地选择梁底、梁中和梁顶3个样地,分0~10,10~20,20~30,30~40,40~50cm 5个土层采集羊柴根围土壤样品,通过Nested-PCR-DGGE技术,结合DGGE图谱分析、DNA克隆测序及系统发育分析进行研究。结果表明,不同样地和土层,AM真菌具有不同DGGE指纹图谱特征,AM真菌丰度、优势度及其多样性指数均有差异,其中梁中和梁顶样地0~10cm土层AM真菌丰富度最高,均为20;多样性指数梁中样地0~10cm土层最高,为2.88。DGGE条带测序和系统发育分析显示,全部序列归为5属15种,分别为Glomus属10种、Rhizophagus属1种、Funneliformis属2种、Paraglomus属1种、Septoglomus属1种;根据UPGMA算法绘制15个样品间AM真菌群落相似性图谱,全部序列归为3个类群,聚类分析显示羊柴根围AM真菌群落具有丰富的遗传多样性,相似性指数最高仅为0.54,说明梁地生境空间异质性对AM真菌遗传多样性有显著影响。受风蚀和水蚀影响,3个样地土壤速效氮差异明显,梁底受侵蚀作用最弱;梁中受侵蚀最强,土壤最贫瘠;球囊霉属Glomus和管柄囊霉属Funneliformis是内蒙古荒漠地区AM真菌优势属,这为进一步筛选高效优势AM菌种,促进荒漠植被恢复提供了依据。

In the present study,we expect to elucidate the genetic diversity and ecological distribution of AM fungi associated with clonal plants Hedysarum leave Maxim under synchronous stress of wind erosion and water erosion,at Qinggeletu in Inner Mongolia,China.Soil samples were collected from 0—50cm depth with an interval of 10 cm in the rhizospheres of H.leave Maxim at three different altitude gradients habitats：the foot-slop,middle-slop and top-slop of the terrace in October 2014.The community composition and genetic diversity of AMF were analyzed based on Nested-PCR-DGGE fingerprint and 18 SrDNA sequencing.The results of DGGE fingerprint revealed significant differences in the composition,richness,dominance and diversity of the AMF communities between different soil layers and habitats.Therichness of AMF community recorded in the 0—10cm layer at the middle-slop and top-slop of the terrace was 20,which was the highest among the sampling habitats.The highest diversity index reached 2.88,and was recorded in the 0—10cm layer at the middle-slop of the terrace.Sequencing and phylogenetic analysis showed that all the sequences were relegated to 15 species belonging to 5genus,which were Glomus（10species）,Funneliformis（2species）,Paraglomus（1species）,Rhizophagus（1species）,and Septoglomus（1species）.UPGMA clustering analysis showed that the sequences could be clustered into 3groups that greatly differed from each other as the highest similarity index was merely 0.54.This meant that the genetic diversity of AMF community in the rhizospheres of H.leave Maxim was significantly influenced by the heterogeneity of the three habitats.Because the synchronous stress of wind and water erosion was different at the three habitats,i.e.,the highest at the middle-slop of terrace and the lightest at the foot-slop,soil available N exhibited significant difference between the three habitats,which consequently significantly influenced the community composition and genetic diversity of AMF.Due to the dominance of Glomus and Funneliformisin the AMF communities in the deserts of Inner Mongolia,high-efficiency species or stains belonging to the two genuses may be selected for improving plant establishment and vegetation rehabilitation in this area.