Study Of Screening, Identification And Growth-promotion Activity Of Endophyte Fungi JP4-1 Of Suaeda Salsa

Endophyte fungi are a kind of microbe that ubiquitously distributed in all kinds of tissues and organs of healthy plants. But they won’t cause diseases to healthy plants. The secondary metabolites produced by endophytic fungi have rich diversity in biological activities and were widely used, such as growth promotion and improving crops ability to resist stress and disease. The secondary metabolites have been the important source for discovery of new leading compounds. Suaeda salsa grows in high salinity soil. Endophytes isolated from Suaeda salsa have abundant diversity and special metabolic mechanism that is beneficial to adapt the living environment of the host. Endophytes also can produce unique active metabolites and a certain influence on the host. That study of the endophyte fungi of Suaeda salsa, analyzing the secondary metabolites, tracking the colonization characteristics and carrying out the kinetic study may have an important significance and potential application value to research the interaction mechanism between the endophytic fungi and host plants.Hydroponic experiments were carried out to screen the most growth-promotion fungi JP4-1 among 5 endophytic fungi which were isolated from Suaeda salsa. Endophytic fungi JP4-1 were identified by using morphological and molecular biological methods. The single factor test and orthogonal test were conducted to investigate the optimum fermentation condition of JP4-1. Some technical means such as filtering centrifuge, ultrasonic crushing and extraction etc. were used to research their metabolites. The expression vector pCT74 with gfp gene was transformed into the protoplasts by PEG-CaCl2 mediated method. Tansformant were detected by fluorescence microscope. Transformant were inoculated in rice seedlings to test its infection characteristics. The main results are as follows:1. Endophyte fungus JP4-1 had the most obvious growth-promotion activities among the 5 endophyte fungi which have growth-promotion activities in rice seedlings in hydroponic experiments.2. The endophyte fungi JP4-1 was identified as Glomerella sp. according to the morphological and molecular biological identification.3. The optimum fermentation condition of JP4-1 is pH 5.0, temperature 25 ℃, liquid volume 50% and fermentation up to 120 hours with 125 rpm, and potato-based liquid culture medium with 4% Sucrose, 0.15%(NH4)2SO4, 0.02% KCl, 0 MgSO4 and 0.2% K2HPO3 by single factor test and orthogonal test.4. The technology of filtering centrifuge, ultrasonic crushing and extraction and hydroponic experiment were used to study the effect of JP4-1 strains fermented liquid active ingredient on the growth of rice seedling. Shoot height, dry weight and the chlorophyll content of rice seedlings, which treated by small molecules extracellular extraction from n-butyl alcohol, were increase by 10.84%, 14.67% and 44.22%, respectively. The extraction component included GA, IAA and ABA by High Performance Liquid Chromatography(HPLC).5. The gfp gene was successfully transformed into strain JP4-1 and expressed stably by PEG-CaCl2 mediated method. The transformant were colonized in the roots and leaves of rice seedlings and have some motility.