[Screening of plant growth-promoting rhizobacteria and its effect on seed germination of Polygonum multiflorum].

In this study, the rhizobacteria and actinomycetes of Polygonum multiflorum were screened for the strains with indole acetic acid(IAA)-producing capacity by Salkowski method, the siderophore-producing strains by Chrome Azurol S(CAS) assay, and the strains with inorganic phosphorus-solubilizing capacity by PKO inorganic phosphorus medium. The strains were identified by morphological identification, physiological and biochemical characteristics, and 16 S rDNA sequences. Furthermore, the effect of growth-promoting strains on the seed germination and development of P. multiflorum was tested. The results showed that among 196 strains, two strains F17 and F42 were found to be capable of producing IAA and siderophore and solubilizing inorganic phosphorus simulta-neously. For F17 and F42, the results are listed below: 38.65 and 33.64 mg·L~(-1) for IAA production, 0.85 and 0.49 for siderophore-producing capacities(A_s/A_r), and 1.35 and 1.70 for inorganic phosphorus-solubilizing capacities(D/d), respectively. Comprehensive analysis revealed that strains F17 and F42 were identified as Pseudochrobactrum asacharolyticum and Bacillus aryabhattai, respectively, and both could significantly promote the seed germination of P. multiflorum.

[Reference gene screening for Real-time quantitative PCR in Polygonum multiflorum].

To select suitable references gene of Polygonum multiflorum for gene expression analysis in different tissues, five candidate reference genes like Actin,GAPDH,SAND,PP2A,TIP41 were selected from the transcriptome data of P. multiflorum, then the specific primers were designed. The expression stability of the five reference genes in different tissues of P. multiflorum was analyzed by Real-time quantitative PCR through avilable analysis methods such as geNorm, NormFinder, BestKeeper, Delta CT and RefFinder, to ensure the reliability of the analysis results. The results showed that there were significant differences in the expression levels and stability of candidate genes in different tissues of P. multiflorum. Ct distribution analysis of the expression levels of candidate genes showed that the expression levels of Actin and GAPDH genes were relatively high in different tissues, while the expression levels of SAND, PP2A and TIP41 were lower. The stability of each candidate gene was analyzed by different methods. The results of geNorm analysis showed that the expression of PP2A and GAPDH was the most stable, the expression stability of SAND was the worst, the stability of PP2A was the highest in both NormFinder and Delta CT, the stability of SAND was the lowest, and the stability of Actin was the most stable in BestKeeper analysis. Through the comprehensive evaluation and analysis of the stability of candidate genes by RefFinder, it is concluded that the stability of PP2A gene is the highest, followed by GAPDH, Actin, TIP41, SAND, and SAND gene is the worst. Therefore, the PP2A gene is an ideal reference gene for the analysis of gene expression in different tissues of P. multiflorum.