Study On Diversity Of AM Fungi In Microorganisms And Roots

Belonging to the genus of Elaeagnus, family of Elaeagnaceae, Elaeagnus angustifolia L. is a perennial deciduous shrub or small tree. Through previous survey, E. angustifolia that can survival in arid and saline-alkaline land can entirely be attributed to the endophytes that located within its roots. The interior of E. angustifolia root nodules associate with nitrogen-fixing bacteria and actinomycetes, and the root system harbor mycorrhizal fungi that bestow the plant with drought tolerance. The main contributor inside of the nodules for nitrogen-fixing is Frankia, a kind of actinomycetes who can get association with non-legume and form nodules for fixing atmospheric nitrogen; while strains that play a major role in conferring the plant with tolerance to drought and can get inside the root system of E. angustifolia are arbuscular mycorrhizal fungi (AMF), which are widely distributed in soil and a class of typical endophyte that can form mutualism with host plant. These two kinds of endophytes can form well symbiotic relationship with the roots of E. angustifolia, with the ability of promoting the growth of E. angustifolia, enhancing the absorption of trace elements by roots, elevating yield and stress resistance, as well as improving soil structure and soil fertility.This study focused on the E. angustifolia that cultivated on saline-alkaline land of Zhaodong City, Heilongjiang Province, traditional cultural method was employed to isolated the microorganisms inside the nodules, totally,4 actinomycetes,14 bacteria and 9 fungi were successfully isolated and identified. Of them, two actinomycetes of Frankia were subjected to physiological type test and assigned to A type and AB type; the salt tolerance test results showed that they could grow under 5% NaCl and with the optimum culture condition was at pH value of 7.5 under 32 ℃。The rhizosphere soil of E. angustifolia was got through mesh using wet sieving decanting-sucrose centrifugation method for detecting the spores of AM fungi and 8 AM fungal spores were obtained. Meanwhile, the microbial diversity in root nodules and root system was obtained through molecular informatics analysis, using Paired-End method to construct small fragment library followed by sequence alignment.The isolated strains and the spores would provide the lab with materials for next stage research, and the results would lay the foundations for in-depth research on root nodules and root system of E. angustifolia. Besides, a further understanding of the previous theory documented by literates was obtained, which would help to develop mixed beneficial endophytes agents used for improving stress resistance of E. angustifolia, expending the applications of its seedling cultivation, as well as improving the soil structure and soil fertility of saline-alkaline land. These would meanwhile accelerate the grow speed of other plants in saline-alkaline land, aiding the ecological restoration of the damaged and pullulated environmental, which plays an very important role on the development of sustainable green agriculture and forestry.