Isolation And Plant Growth Promoting Properties Of Endophytic And Rhizosphere Soil Actinolycetes From Tetraena Mongolica

Actinomycetes are a group of mycelioid gram positive bacteria with highly(G+C)%content.They can also produce varieties of secondary metabolites,which makes them have important values in research and application.Endophytic actinomycetes are those which in their whole or partial life cycle colonized in the healthy plant tissue without causing any significant disease.In nature,a pair of cozy coevolutionary symbionts between plant and endophytics have been formed for a long time.,which makes endophytics can be beneficial for the host plants.Rhizosphere soil actinomycetes are living in the vicinity of plant rhizosphere soil and it can interact more direct with plants than any other soil isolates.Rhizosphere soil actinomycetes also have many excellent properties to promote plants growth.Tetraena mongolica is an arid and saline-tolerant Tethys flora relict plant,the endophytic and rhizosphere soil actinomycetes are still not unveiled.Tetraena mongolica and its rhizosphere soil are good resources for actinomycetes.Isolation and identification plants growth promoting actinomycetes from Tetraena mongolica have great potentials.Tetraena mongolica and its rhizosphere soil were collected from Wuhai region,Inner Mongolia,and then were used for isolation of endophytic actinomycetes and rhizosphere soil actinomycetes.The properties of plant growth promoting for isolates were studied.The results are as follows:1.11 strains with typical characteristics of actinomycetes were separated from Tetraena mongolica tissue samples and another 11 isolates were isolated from its rhizosphere soil.2.The properties for plant growth promoting for all the isolates were detected.All of the 22 isolates have different abilities for phosphate solubilization and can produce IAA,the solubilisation of inorganic phosphorous ranging from 4.68 to 214.5?g/100ml and the amount of indole-3-acetic acid(IAA)produced ranging between 0.006-0.933 ?g/ml.8 isolates can produce chitinase.18 isolates have the ability to produce siderophores.Ammonia,HCN and urease production can be detected in 12,2 and 21 different isolates,respectively.Then we conducted a comprehensive ranking according to their ability in plant growth promotion,RE4,RS7,FE1,FE3,FE4 were selected as top five isolatesfor the following tests.3.To gauging the potential antagonistic of top five isolates,the antimicrobial activities were tested against four fungal phytopathogens and four bacteria.Among the 5 isolates,all isolates showed inhibitory activity against at least one tested pathogen and RE4.RS7 couldinhibit all the microorganisms.All of 5 isolates showed significant inhibitory activity against two plant-pathogens,i.e.Fusarium oxysporwn and Verticillium dahliae Kleb.The five isolates also showed clear activity against Sclerotinia sclerotiorum,except FE4.All the isolates could inhibit the growth of Staphylococcus aureus.4.The germination experiment showed that compared with control group,five isolates showed different inhibitory effects on tomato seeds.The germination rate of the control group was 75%,and the germination rate in the experimental group was 61.67%as the highest rate(FE4)and the lowest rate(FEI)was only 38.33%.It showed a significant effect on the inhibition of seeds germination of tomato.The effect of RE4 and FE1 on the inhibition of germination were stronger than the other isolates.The inhibition was not only displayed in the germination rate,but also in the average sprout length after germination.The average shoot length of FEI group was the shortest and the germination rate was the lowest,and the germination inhibition effect of tomato seeds was the most obvious.5.Then the culture characteristics of the top five strains were detected.Strains RS7,FE3 and FE4 could grow at temperatures of 4? to 45?.and they grew better as the temperature increased.Strain FEI could only grow at 30? and RE4 could grow at temperatures upon 4?.In the pH tolerance test.The results showed that the strains RE4 could grow in the liquid nutrient medium with range of pH 5.0 to 12.0.IRS7 could growth under pH 3.0 to 12.0,FE4 could only growth under the pH 7.0 condition.RE4,RS7 and FE3 strains were extremely halophilic and could grow on medium with NaCl content of 15%to 20%.Meanwhile,in the heavy metal tolerance test,RE4 and RS7 could form colonies on the medium with zinc ion concentration of 100 mg L-1.6.The physiological and biochemical activity test showed that all the five actinomycetes could use mannitol,xylose,fructose,sucrose and arabinose as carbon source and all of them could produce cytochrome oxidase and H2S.All five strains could produced lipase and catalase,and also nitrate reduction activity.RE4 was positive for gelatin liquefaction.RE4,RS7 and FE4 had amylase activity.RE4,FEI and FE3 had cellulase activity.RS7 could make litmus milk fade,the remaining strains were as same as the blank control.