Isolation Of Endophytes From Sesbania Cannabina And Plant Growth-promoting Characteristics Of Endophyte

Endophytes are microorganisms that can be symbiotic with plants.Endophytes usually have special growth-promoting properties that can promote plant growth.Therefore,isolation of endophytes as growth-promoting bacteria can promote the development of environment-friendly agriculture.Reduce the impact of agricultural production on the environment and promote the bioremediation function of plants.There is more research on endophytes in cereals such as corn and rice,or tissues like root and stems,but the research about endophytes in seeds is lesser.In this study,Sesbania cannabina seeds were used as experimental objects.81 strains were isolated from LB medium and Gause?medium.Phylogenetic analysis was performed by amplifying 16 S r DNA sequences of bacteria and ITS sequences of fungi.The strains were tested for IAA production,phosphorus solubilization,siderophores and ACC deaminase activity.Based on the test of growth-promoting properties,the strains with potential for growth-promoting bacterias were screened by seed germination test,plate confrontation test,and pot experiment.The main results are as follows:(1)Isolation of endophytes in seeds and identification of growth-promoting characteristics:81 endophytes were isolated from Sesbania cannabina seeds,belonging to four generas.Their relative abundances are Azorhizobium at 46.9%,Bacillus at 45.7%,Rhodotorula and Cellulosimicrobium at4.9% and 2.5%,respectively.41.97% of endophytes had the ability to produce IAA,49.38% endophytes with phosphorus solubilization,69.14% endophytes had ACC deaminase activity,and only one endophyte could produce siderophores.(2)The detection of seed endophyte to promote seed germination:SC45,SC60,SC59,SC17 can increase the vigor coefficient of Sesbania cannabina seeds,which can increase 13.3%,14.1%,29.9%,26.7%,respectively.Soaking seed with SC60 and SC17 strains can significantly promote the development of radicle,and the proportion of radicle has increased by 29.5% and13%.Germination experiments prove that Bacillus SC60 has the ability to produce IAA,phosphorus solubilization and ACC deaminase activity,soaking seeds with endophytes can improve seed vigor,promote radicle development,and can be used as potential PGPB.(3)Antagonism of seed endophytes to plant pathogens:The antagonism rate of SC45 against Rhizoctonia solani was 60.38%,and the antagonism rate to Botrytis cinerea was 28.26%.And the fermentation broth has a certain inhibitory effect on Fusarium oxysporum.SC45 can be used to control plant diseases and applied to agricultural production.(4)Effects of endophytes on the resistance of plants to heavy metal stress:Inoculation with copper-tolerant bacteria SC35 can increase the chlorophyll content of plants under copper stress.Combined inoculation of SC35 and rhizobium Ensifer alkalisoli YIC4027 can promote the biomass of Sesbania cannabina.SC35 can be used to improve the growth and development of plants under copper stress,and combined inoculation with Ensifer alkalisoli YIC4027 was better than single incubation?...