Characterization of diazotrophic growth-promoting rhizobacteria isolated from ginger root soil as antagonists against Ralstonia solanacearum
2018
Jian Zhang | Tingting Guo | Pengcheng Wang | Hongmei Tian | Yan Wang | Jingyi Cheng
Bacterial wilt caused by Ralstonia solanacearum (RS) has become one of the most destructive plant diseases in agricultural crops. Obtaining effective strains with disease control activity is an urgent prerequisite for biological control efficiency. This study was performed to explore if the root-associated diazotrophic rhizobacteria in ginger plants have any potential to induce resistance to RS. Three bacterial strains named N10, SJN3 and SJN5 were obtained from the rhizosphere soil of ginger root and were further evaluated regarding their high inhibitory activity in the preliminary screening and in vitro antagonistic activity against RS. Inoculation with N10, SJN3 and SJN5 showed 47.61%, 49.33% and 43.15% relative disease incidence, respectively. N10 and SJN5 showed the most successful biocontrol efficacy and reduced disease incidence by 39.98% and 45.61%, respectively. Moreover, N10 and SJN5 promoted root length by 25.5% and 26.6%, shoot dry weight by 12.5% and 20.1% and root dry weight by 15.4% and 17.9%, respectively. According to the 16S rDNA partial sequence, N10, SJN3 and SJN5 belonged to the genus Pantoea, Burkholderia and Arthrobacter, respectively. Fluorescent in situ hybridization assay revealed that SJN5 cells were distributed on the root surface and formed a condensed biofilm. This result suggests that this strain, which shows nitrogen fixation and antagonism toward RS, not only can increase plant growth, but can also inhibit plant diseases. The findings of the present study expand our current understanding on the application of diazotrophs as a bacterial biocontrol agent, especially for Arthrobacter sp.
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