| Chemical fertilizer overapplication and plant disease are serious problems in Aconitum carmichaelii Debeaux cultivation.Therefore,it is urgent to find efficient and green approaches such as bio-fertilizers and biocontrol materials to improve planting efficiency,in this study,Culturable endophytic bacteria were isolated from surface sterilized healthy plants of A.carmichaelii,and their IAA-producing capacities were measured by Salkowski spectrophotometry.The genetic diversity and phylogenetic status of high IAA production bacteria were studied via 16 S r DNA-restriction fragment length polymorphism（16S r DNA-RFLP）and 16 S r DNA full-length sequence.The effects of IAA-producing endophytic bacteria on the seed germination rate of rice were tested by semi-solid culture method after the seeds were immersed in bacterial liquids for 30 min.The effects of the endophytic bacteria on rice seedling growth were investigated by hydroponic experiment in our laboratory.The antagonistic endophytic bacteria of A.carmichaelii white rot and root rot were screened by plate antagonistic method and the effects of antagonistic endophytic bacteria on growth and disease resistance of A.carmichaelii were verified by field test.The main results are as follows:（1）A total of 285 endophytic bacteria strains were isolated from different tissues and organs of healthy A.carmichaelii from main growing areas of Sichuan,Shaanxi and Yunnan,including 114 strains（52 in root,37 in stem and 25 in leaf）from Sichuan,70 strains（37 in root,31 in stem and 2 in leaf）from Shanxi and 101 strains（45 in root,40 in stem and 16 in leaf）from Yunnan.（2）Among the endophytic bacteria isolated from Sichuan,Shaanxi and Yunnan,162 strains could secrete IAA,among which 24 strains had high production of IAA in Sichuan.The 16 S r DNA analysis indicated that identification included Enterobacter,Klebsiella,Pantoea,Pseudomonas,Microbacterium,Bacillus and sphingosphenol and Chryseobacterium;which has ten bacteria isolate from Shaanxi province belonged to Pseudomonas,Serratia,Priestia and Bacillus.The six strains in Yunnan province belonged to the genera Novosphingobium,Agrobacterium,Pseudomonas and Bacillus.The endophytic bacteria JY-1-1S,JY-3-6S and JY-10-1L were screened from the above endophytic strains with high yield of IAA in A.carmichaelii,which showed good effect on seed germination and seedling growth.（3）Among the endophytic bacteria isolated from A.carmichaelii,the endophytic bacterium JY-7-2L screened by plate confrontation method showed the strongest antagonistic activity against pathogens,and it could significantly reduce the disease incidence of A.carmichaelii after inoculation in the field.It was identified as Bacillus subtilis by 16 S r DNA.The results showed that the endophytic bacteria in A.carmichaelii were rich in resources.It also has the ability to produce indole acetic acid and antagonize aconitum white rot and root rot.In this study,three endophytic bacteria significantly promoted the seed germination and seedling growth of rice and one endophytic bacteria significantly inhibited the disease of A.carmichaelii.It provides high-quality strain resources for the development of related microbial fertilizers and biological bacteria agents of A.carmichaelii,and provides scientific and technological support for the green and sustainable development of A.carmichaelii cultivation in genuine producing areas. |
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