Study Of Plant-Growth Promoting Rhizobacteria In Growth Promotion, Biocontrol And Stress Resistance Screened From Different Stressed Soils By Using Oil Rape Bating Cycling

By using a combination of baiting and rhizosphere colonization cycling assays with oil rape seed as host in different stressed soils,110,139,141and228bacteria colonies were isolated from heavy metal polluted, recalcitrant organic contaminated and petroleum semeary and saline zone of plant rhizosphere in China, respectively, and15.5%,15.1%,36.2%,24.6%of isolates inhibited Sclerotinia sclerotiorum accordingly. Randomly selected414colonies were conducted1-aminocyclopropane-l-carboxylic acid (ACC) Deaminase-containing rhizobacteria screening, about17%of selected colonies showed positive activity.We investigated12rhizobacterial isolates representing3dominant morphotypes, Pseudomonas sp., Bacillus sp., and Micobacterium hydrocarbonoxydans. Phylogenetic analysis of phlD, prnD, pltC, phzF and acdS genes sequences in Pseudomonas showed that P. protogens KY1502, TY1508containing key gene in biosyntheses of2,4-diacetylphloroglucinol (Ph1or2,4-DAPG) and pyoluteorin (PLT), which tightly clustered to well known Pseudomonas strains Pf-5; and P. brassicacearum TY1205, P. brassicacearumTY1210, P. brassicacearum KY5404, P.fluorescens TY3101, KY3201contained the gene in biosyntheses of ACC deaminase, the P. brassicacearum strains showed tigh clustering to P. brassicacearum Q8r1-96.All12strains were tested for their abilities of growth promotion under gnotobiotic condition oil rape seed elongation assay, the ability of phosphate solubilization and stress resistance in heavy metal and salt stresses. All P. brassicacearum strains containing ACC deaminase and P. protegens strains increase the length of root significantly and consistently, in comparison with the negative control. Based on biocontrol assays and heavy metal test, ACC Deaminase-containing isolates showed more highly effective suppression of S.sclerotiorum and resisted higher concentration heavy metal. ACC Deaminase-containing PGPR P. brassicacearum KY5404indicated stable inhibition of S. sclerotiorum in greenhouse treatment and increased oil rape seed growth significantly.