| Arbuscular mycorrhizal (AM) fungal is a very important microorganisms in the soil。It can form arbuscular mycorrhizal mutualistic symbionts with most of the land plants.So it is play an important role in the linking above and below ground ecosystem.AM fungal can promote plant growth by supplying nitrogen and phosphorusto plant roots in return for plant assimilates. Also it can improve the disease resistance of plants. At the same time, AM fungi can change the secondary metabolism of plants and the diversity of plants community. The environmental remediation is influenced by the AM fungal. On the other hand altitude, season and other environmental factors will impact on the diversity of AM fungi. The Qinghai-Tibet Plateau studied in the experiment is a special ecosystem. Few studies are about the AM fungi in this area. The experiment is on the AM fungi which forms symbiotic associations with different Dracocephalum heterophyllum in the Qinghai-Tibet Plateau. The diversity of AM fungi which forms mutualistic associations with the roots of Dracocephalum heterophyllum is studied by the method of PCR-RFLP. The results elaborate the diversity of AM fungi of the roots of Dracocephalum heterophyllum in the Qinghai-Tibet Plateau, as well as the adaptability of AM fungi for different type of environments. And it provides a good theoretical guidance for the protection and recovery of the ecosystem of the Qinghai-Tibet Plateau.The main findings are as follows:1. In this study, a total of13sampling sites, environmental factors was measured and results are as follows:soil available nitrogen, the largest is7.57±1.79mg/kg and the smallest is2.53±0.41mg/kg; soil available phosphorus, the minimum value of1.83±0.22mg/kg, and a maximum value of7.86±1.86mg/kg; Available N:available P2.88±0.71up to0.69±0.16; pH ranging8.65±0.04to6.77±0.03; soil organic carbon vary from0.05±0.001%to1.98±0.13%; soil total nitrogen, the highest level of0.19±0.02%, the lowest level of0.05±0.001%; plant shoot nitrogen minimum value of19.65±1.83mg/kg, the maximum value of37.18±1.62mg/kg; plant shoot phosphorus the top is2.41±0.15mg/kg and the bottom is1.50±0.11mg/kg.2. Twenty-six AM fungal species were found in the roots of Dracocephalum heterophyllum of thirteen different sampling sites in this experiment. They belong to seven families. In these seven families, there are fifteen belong to Glomerceae, two to Acaulosporaceae,one to Entrophosporaceae, three to Diversisporaceae,two to Claroideoglomeraceae, two to Archaeosporaceae and one to Paraglomeraceae.And Glomerceae is the biggest groups in the roots of Dracocephalum heterophyllum of all samples, followed by Claroideoglomeraceae and Diversisporaceae. Other families are all rare and only found in the roots of Dracocephalum heterophyllum of some sampling points. Ten species in twenty phylotypes are similar to the known AM fungi.3. The richness of AM fungi in the different sampling sites changed to2.8±0.49to5.4±0.51. three families six genus nine species in Wudaoliang, three families five genus six species in Beluhe, three families four genus five species in Tuotuohe, four families six genus nine species in Namucuo, five families seven genus eight species in Nalongcun, three families six genus seven species in Luomazhen, three families six genus six species in Anduola-guozuxiang, four families six genus eight species in Anduo, four families five genus nine species in Yanshiping, three families five genus six species in Fenghuoshannan, five families six genus seven species in Budongquan, three families five genus seven species in Xidatan, four families eight genus thirteen species in Qinghaihu. AM fungal community Shannon Wiener index is0.58±0.11to1.24±0.21.4. NMDS ordination analysis and fitting of the environmental factors found that elements affecting AM fungal in the roots of Dracocephalum heterophyllum are altitude, soil available nitrogen, plant shoot nitrogen plant shoot phosphorus ratio, of plant shoot nitrogen.5. The pH, soil available phosphorus, soil available nitrogen, the ratio of available nitrogen and phosphorus, soil organic carbon, soil total nitrogen, altitude, latitude and longitude are selected in different point as indicators. We classified environment by K-means. The13sampling sites are divided into four environmental groups, ENV1to ENV-4. ENV-3is the largest environmental group, the AM fungal molecular species in this group is maximum, and the endemic species are greater. |
