Isolation And Identification Of Endophytic Diaotrophic Bacteria From Maize And Their Effect On Wheat Seedling Growth

Forty two strains of endophytic diazotrophic bacteria were isolated from root, stalk and leaf of maize using the grinding method. We analysed the nitrogenase activity of them, and then evaluated the plant-growth promotion ability by IAA production experiment, phosphate solubilization ability of isolates L1A1, L1A4, L1B9 and L2A2 which had higher nitrogenase activity. All the strains produce IAA more or less. Isolates L1A1 and L2A2 had phosphate solubilization ability. Curvulavia lunat, Valsa mali, Alternaria alternate, Botrytis cinerea, Fusarium graminearum and Fusarium oxysporum were utilized to study the antagonism ability. Three methods were taken: plate assay, filter paper method and Growth rate method. It shows that L2A2 had in vitro antagonistic ability on Curvulavia lunat, Valsa mali, Alternaria alternate, Botrytis cinerea and Fusarium oxysporum, well L1A4 only proform a feeble affect on Fusarium graminearum. L1A4 and L1B9 showed no antagonistic ability. By comparison, growth rate method was the best way to detect the bio-control characteristics of the endophytic diazotrophic bacteria.Four of them which had high nitrogenase activity were studied by way of morphological and physiological-biochemical properties. We sequencinged the PCR production of 16S rDNA, and then obtained the accession number to Genbank. L1A1 (HQ739094) was identified as Acinetobacter johnsonii as well as L1A4 (HQ739094) was Sphingomonas panni, L1B9 (HQ739094) was Sphingomonas yabuuchiae and L2A2 (HQ739094) was Staphylococcus pasteuri.We also analyzed the effect on wheat seeding by inoculated the isolates to wheat in the axenic condition by pot experiment. The group didn t inoculated the isolate was taken as negative control; The wheat watered with liquid nitrogenous fertilizer was taken as positive control group. The measuring results indicated that all the four isolates could increase the growth parameters of wheat seeding, such as shoot length, root lenth,fresh biomass and dry biomass with a differ significance(P<0.05). this demonstrated that the four strains had effect on wheat seeding growth and development and make the seeding stronger. At the same time the inoculation of endophytic diazotrophic bacteria could increase the soluble protein content and the activity of oxidation protective enzymes endow the resistance of wheat seeding.Conclusion:The endophytic diazotrophic bacteria isolated from maize had high biodiversity and growth-promoting effect on plants.