Study on the Effect of Rhodococcus rhodochrous NB1 on the Tolerance to Salt and Growth-promoting of Maize and Its Whole Genome
[Objective]To study the salt tolerance and growth-promoting characteristics of Rhodococcus rhodochrous NB1,analyze its whole genome information,and explore the salt tolerance promoting genes of NB1 strains.[Method]NB1 strain were identified using morphological observations and 16S rRNA gene sequence analysis.The nitrogen fixation,phosphorus lysis and ACC deaminase production were identified by modified medium,Pikovaskaia's medium,DF liquid medium and ADF liquid medium.The NB1 strain was inoculated to NB solid concentrations of 0,5％,10％and 15％on the trophic base,the tolerable concentration of the strain was determined after 48 h of incubation.Maize seeds treated with and without the NB1 strain were inoculated onto 1/2 MS medium,and the plant height,root length,fresh weight and root weight were determined after 15 d of continuous culture.Growth indicators of maize seedlings watered and untreated with NB1 broth were measured in the form of pot experiments under the same salt concentration stress.Whole gene analysis of NB1 strain was conducted using Illumina second generation sequencing and PacBio third generation sequencing.[Result]The NB1 strain belongs to Rhodococcus rhodochrous,it may produce ACC deaminase,has the ability of fixing nitrogen and dissolving phosphorus,and may tolerate the salt concentration of 5％.Under soil-free culture conditions,the plant height,root length,fresh weight and root weight of maize seedlings treated with NB1 strain increased significantly.After pot planting,the plant height and fresh weight were significantly higher than that of CK.The NB1 strain has 5 259 coding genes,the total length of coding genes is 5 230 674 bp,and the average GC content is 68.30％.They are annotated to 5 235,4 379,4 195,3 758,3 263,and 2 449 genes in NR,Pfam,COG,Swiss-Prot,GO,and KEGG databases,respectively.The protein structures encoded from 178 genes in NB1 strain belongs to the CAZy family and containing genes of chitinase,sucrase and other enzymes.Mean while,it is predicted that there are 14 secondary metabolite gene clusters,457 virulence factors and 324 resistance genes in NB1 strains,and related genes such as tetrahydropyrimidine and tetracycline antibiotics with salt resistance and promoting properties were found from the NB1 genome.[Conclusion]Rhodococcus rhodochrous NB1 has salt resistance and growth promoting effect on maize,which provides new strain resources for plant salt resistance.
万方数据
维普
