Screening Of Affinity Rhizosphere Phosphate-Solubilizing Bacteria From Wheat And The Growth-Promotion Effects On Wheat

The aim of this paper is to screen the affinity of wheat phosphate-solubilizing bacteria(PSB)and investigate the promote effect of PSB on the growth of wheat.The study preliminary screened PSB by the method of phosphate solution medium and secondly screened by the method of lectin which was labeled by fluorescein(FITC),acquired a many of affinity PSBs.Through the study of the growth promoting ability of these strains,two strains which have excellent growth promoting properties were choosed and were labeled by light emitting enzyme lux AB gene.By the method of root bag test,tracked two labeled strains' time and space characteristics of colonization,and the development of root system.The aim of the study is to provide a theoretical basis and experimental materials for the development of bio-fertilizer for wheat.According to the method of grinding and sieving,acetone extraction,petroleum ether degreasing,PBS extraction,ammonium sulfate precipitation,65 °C hot water treatment and micro filtration in 4 °C layer cabinet to extracted wheat germ agglutinin.The methods of phosphate-solubilizing bacteria culture and tobacco lectin were applied,and 22 wheat germ affinity PSB strains with a high potential for growth-promotion were selected from healthy wheat seedlings rhizosphere soil.P12's ability to dissolve phosphorus was the strongest.The screening PSBs were detected by the method of study on growth promoting characteristics.wheat germ affinity PSB strains were detected phosphate-solubilizing capability by the method of molybdenum blue colorimetry.Test results prove that,Total 7 PSBs strains' phosphorus concentration in the culture medium was more than 100?g/ml,at the level of 179.3 ?g/ml;the test of producing iron carrier showed that,total 22 PSBs have the ability of producing iron carrier,there are 11 PSBs strains' capacity of producing iron carrier at the level of 5+;the test of producing IAA showed that,total 20 PSBs have the ability of producing IAA,the IAA concentrations of broth of 18 strains were more than 10?g/ml,P3' ability of producing IAA was the strongest,reached the level of 42.99 ?g/ml.P23's ability to solved phosphorus was the strongest,reached the level of 130.1?g/ml.Plate confrontation test to investigated the inhibitory effect of Wheat Rhizosphere on 5 plant pathogens,the result showed that 4 PSBs have the inhibitory effect on 5 plant pathogens,P15 and P20 have inhibitory effect on Rhizoctonia cerealis and Gaeumannomyces graminis effect.In order to identified 22 wheat germ affinity PSBs species,adopted the method of combining the morphology experiment,physiological and biochemical tests,and 16 SrDNA,22 wheat germ affinity PSBs were identified to belong to 6 genera.Bacillus sp.,Pseudomonas sp.,Arthrobacter sp.,Mucilaginibacter sp.,Massilia sp.,and Telluria mixta sp..According to the above test results,two outstanding PSBs were selected to label luxAB gene by the method of electrotransformation,acquired labeled P34-L and WS32-L,after successive transplantation,it was prove that plasmid DNA can be stably inherited.The ability of dissolving phosphate and producing iron carrier were determined to check the difference of the original strains and labeled strains,and found the difference is very small,the exogenous plasmid DNA transformed did not change the growth promoting characteristics.Using root bag to grow wheat,two labeled strains were inoculated into the root of wheat,and were used to detect the time and space characteristics of colonization,and the development of root system.The test showed that 2 labeled strains had different colonization levels in different time and space,on the 6th day of wheat growth,P34-L and WS32-L have reached the depth of 8 cm with the growth of wheat root and kept high density colonization in various parts of the root;on the 12 th day of wheat growth,on the 12 th,18th,30 th day of wheat growth,because of the external environment factors,caused the colonization number of 2 labeled strains in different root segments showed a dynamic level.On the 36 th day,the density of the 2 labeled strains was increased at 8 cm,The colonization densities of P34-L and WS32-L respectively reached 1.1×107 CFU·g-1?1.3×106 CFU·g-1.Two labeled strains significantly promoted root growth and dry matter accumulation of wheat,significantly promoted the ground dry weight,root dry weight and total dry weight of plant accumulation,significantly promoted the total root length,number of branches and extreme significantly promoted the number of root tips cross.Total two strains had strong ability of colonization,they can live long settle down in the rhizosphere of wheat,can promote dry weight of plant accumulation and root development,play an positive impact on the wheat growth and development.