Abstract:

【Objective】 Phylogenetic tree was constructed from 15 standard potato scab pathogen strains and 34 scab-causing strains isolated from 8 provinces in China based on the 16S rDNA gene sequences. 【Method】 16S rDNA sequences were obtained using Streptomyces genus universal primers and genomic DNA as amplified template by PCR technique. BLASTn algorithm was used to search alignment for the sequences of 16S rDNA gene from the 49 strains against GenBank nucleotide database. Among them, strains with higher sequence homology were used to construct a phylogenetic tree by Clustal X 1.8 and MEGA 2.1 softwares. 【Result】 Based on the results of phylogenetic analysis, the 34 scab-causing strains tested in this paper were attributed to the Streptomyces genus. Among them, 12 strains belong to S. scabies, 8 to S. galilaeus, 6 to S. bobili, 2 to S. diastatochromogenes, 1 to S. turgidiscabies, 1 to S. acidiscabies, 1 to S. setonii, and 3 to S. enissocaesilis. Moreover, S. galilaeus, S. bobili and S. enissocaesilis are identified as novel potato scab pathogens for the first report. Four strains were isolated from Shandong province, 3 from Inner Mongolia province and 3 from Shaanxi province, 2 from Hebei province, 2 from Shanxi province, 1 from Heilongjiang province. 【Conclusion】 Results suggested that genetic diversity and complex regional distribution existed for potato scab pathogens in China.

Key words: potato scab, Streptomyces, 16S rDNA sequence, genetic diversity