Plant Growth-promoting And Stress Tolerance Effect Of Marine Habitat Bacillus Velezensis CT2628

In order to provide a theoretical basis for the application of microbial fertilizer,we studied the growth promoting and stress resistance effects of the Bacillus velezensis CT2628 isolated from sea mud.Through a series of physiological and biochemical reactions and pot experiments,the preliminary mechanism of the strain was revealed which were followed up:1.The physiologycal experiments of growth promoting and stress resistance were carried out,and the results showed that CT2628 have following characteristics that it can produce biofilm,fix nitrogen,degrade phosphorus,siderophore and the phosphorus degradation rate almost 161.9%,it produce IAA 43.67 mg/L,Drought experiment simulated by PEG6000 showed CT2628 can resist severe drought stress.The strain could still grow on LB medium which contain 15%salt.Therefore,it is preliminarily proved that CT2628 is a strain which can promote plant growth and induce plant resistance to salt and drought stress.2.Afterwards,the interaction between CT2628 and plants was explored,the results showed that 400times CT2628 wettable powder can promote plant growth,induce root volume increase 71.5%and increase 47.2%in root vigor.The CT2628 can slow down the rate of water loss and enhance the water retention capacity of plants and enhance photosynthesis of plants.The strain can also stimulate the increase of osmotic substances and ensure the normal growth of plants under drought conditions.,stabilize the endogenous hormone levels of IAA and ABA,and effectively induce drought resistance.The test of inducing plant salt resistance proved that the l antioxidant enzymes such as SOD,POD,and CAT increased by 119.8%,35.1%and 64.19,respectively,MDA decreased by 149.1%.Our research proved that CT2628 inoculation can promote plant growth and induce plant resistance to salt and drought stress.3.In order to persue the mechanism of growth promoting and stress resistance,we sequenced the whole genome.The results of the third generation sequuencing showed that total genome length of CT2628 is 4 122 800 bp,the G+C content is 38.09%.The total of 3358 genes are divided into 22 COG groups,most of genes are involed in amino acid metabolism,carbohydrate transportion,innorganic transportion,cell motility and metabolism.CT2628 contains genes related to growth promotion and stress resistance such as nitrogen-fixing gene(nif U),spermidine synthesis gene(spe A、spe B),Na~+/H~+retrorse transferring protein gene(mrp B),the results of prediction of secondary metabolites of CT2628showed that it can produce lipopeptides and siderophores and carotenoid in oder to involve process of growth promoting and stress resistance.The third generation sequuencing showed that CT2628 have many genes related to plant growth promoting and stress resistance.