The Diversity Of Endophyte Fungi In Leymus Chinensis And Its Effects On Host's Resistance To Saline-alkali In Songnen Grassland

In nature,there are complex microbe communities in most of plants.In those communities,the fungi which have symbiosis with their hosts are called endophyte fungi.Interaction between microbe and plant is one of the most important topics in ecology and there are lots of studies illustrate that the endophyte fungi have varieties of interactions with their hosts.Most of these interactions are beneficial to their hosts on the tolerance ability of habitats.In Songnen grassland,the Leymus chinensis is a constructive specie which has great adaption to Saline-alkali soil.Previous studies on this adaption are focused on the Physiological changes of L.chinensis itself and the interaction between the underground parts with arbuscular mycorrhizal fungi(AMF),but they ignore the effects of interaction between endophyte fungi with its host.So we want to reveal the diversity and distribution of endophyte fungi in L.chinensis.Meanwhile,we also want to do research on its effects on host's resistance ability to Saline-alkali.In our research,we do field experiments and then use the high throughput sequencing technology to study the community construction of endophyte fungi in L.chinensis along Saline-alkali gradient under natural conditions.At the same time,we determine the physical and chemical properties of soil in the sample plots to analyze the factors that influence the community construction of endophyte fungi in L.chinensis.Besides,we also do Three-Factor pot cultured experiment to study the effects of single and multi-endophyte fungi on their host ability of resistance to saline-alkali.It is illustrated by our study that:(1)There are many kinds of endophyte fungi in L.chinensis in Songnen grassland,totally 105 genera.The composition of advanced genus between plots is similar,but the relative abundance of each advanced genus is different.The Alternaria is the most advanced genus in whole Songnen grassland and it has stable symbiosis with L.chinensis.(2)Physical and chemical properties of soil are important factors which can influence the endophyte fungi construction.The pH,electrical conductivity,moisture,total nitrogen and total organic carbon of soil all have effects on community construction of endophyte fungi in L.chinensis.Among these factors,moisture,total nitrogen and total organic carbon of soil are the main factors.(3)The effects on L.chinensis'resistance to saline-alkali are varied by the kind of endophyte fungi.Both Alternaria and Cladosporium can significantly expand L.chinensis'tolerance range of Na~+.Sporobolomyces can significantly decrease production of peroxide in L.chinensis to protect membrane system.Meanwhile,it also can significantly increase the osmotic adjustment substance content to maintain cell osmotic pressure.When different endophyte fungi are in the host at the same time,there are significant interaction effects between them.Totally,we first identify the complex endophyte fungi community construction of L.chinensis in Songnen grassland and find the main factors which affect the community construction are soil total nitrogen and total organic carbon.Then we find that kinds of endophyte fungi can work together to improve host's resistance to Saline-alkali,this may be a new prospective to explain why L.chinensis can survive in Saline-alkali soil.Last but not least,the endophyte fungi we isolated can be made into biological agents,which may help cultivation of L.chinensis on Saline-alkali soil.