Identification And Determination The Plant Growth Promoting And Biocontrol Properties Of Paenibacillus Polymyxa ZYPP18

In this study,a strain isolated from soil was identified as Paenibacillus polymyxa by morphological identification and molecular identification.The growth-promoting effect of the strain on wheat and the disease prevention of wheat sheath blight were analyzed.The results of the research are as follows:1.The strain was isolated from soil and the colony was white,opaque,uplifted,higher than the central part,and Gram stain was positive.16 S rRNA was obtained by cloning,and the accession number of 16 S rRNA sequence on NCBI was MF967209.The sequence was BLASTed with the known nucleotide sequence in NCBI(https://www.ncbi.nlm.nih.gov/).Phylogenetic tree was constructed by a with Mega 6.0 and the strain was identified as Paenibacillus polymyxa Which was named as ZYPP18.2.P.polymyxa ZYPP18 was cultured on Monkina organophosphorus medium and PKO inorganic phosphorus medium.After incubation at 37°C for 5 days,a transparent circle around the colony was found.The average diameter was 1.20 cm,2.07 cm respectively.Calculation of clear circle/colonial diameter(D/d)was 1.44,1.56 respectively and it was determined that the strain had phosphate-solubilizing activity.By measuring the pH of the culture fluid of the strain and the content of orthophosphoric acid,it was revealed that P.polymyxa ZYPP18 has the ability of dissolving phosphate.Salkowski colorimetric method was used to determine the content of IAA,which reached 2.74 mg/m L.In the medium supplemented with L-tryptophan,the IAA content of this strain reached 3.05 mg/mL.The results that the strain contains auxin synthesis-related genes was found.In the hydroponics experiment and potted experiment,through measuring the growth index of wheat,it was found that after P.polymyxa ZYPP18 treatment,the indicators of wheat growth were better than the control and it indicates that ZYPP18 has a promoting effect on the growth of wheat.3.The antagonistic experiment between P.polymyxa ZYPP18 and Rhizoctonia solani showed that ZYPP18 had a significant inhibitory effect on the growth of Rhizoctonia solani,and the inhibition rate reached more than 92%.ZYPP18 sterile filtrate by culturing can inhibit living of Rhizoctonia solani and different concentrations of fermentation filtrates have different inhibitory effects.By experiment of wheat in vitro,it was found that the incidence of wheat sheath blight in wheat leaves treated with ZYPP18 was significantly lower than that of wheat leaves treated with water.The mycelium of Rhizoctonia solani expanded on the surface of wheat leaves during 3 days and on the 3rd day,lesions appeared and expand in the leaves.By pot experiments and field experiments,we found that ZYPP18 has a good disease-preventing effect against wheat sheath blight.P.The control effect of polymyxa ZYPP18 on wheat sheath blight reached 56.30% in the pot experiment and 65.57% in the field experiment.4.Genes of P.polymyxa ZYPP18 related with the synthesis of antibacterial compounds by PCR was performed and found that it contain genes encoding polymyxin,Fusaricidins,?-glucanase,cellulase,and CEL44C-MAN26 A.That indicates that the strain has perfect biocontrol potential activity and possible mechanisms for the control of wheat sheath blight.