rDNA-ITS and 28 S rDNA D1/D2 sequence analysis of downy mildew pathogen from Aconitum carmichaeli / 中草药

ABSTRACT

Objective: To define sequences about rDNA-ITS and 28 S rDNA D1/D2 of Peronospora aconiti separated from cultivated Aconitum carmichaeli in Jiangyou area of Sichuan province and provide a theoretical basis for the diagnosis and prevention of downy mildew disease. Methods: Spores and hyphae of P. aconiti from diseased plants were collected and total genomic DNA of pathogen were extracted and then rDNA-ITS and 28 S rDNA D1/D2 fragment were amplified and sequenced. According to the above results, the abutment (Neighbor-joining, NJ) phylogenetic tree of pathogen was constructed and analyzed. Results: The rDNA-ITS and 28 S rDNA D1/D2 sequences of P. aconiti were sequenced and compared according to the database from NCBI. Compared that with P. pulveracea and P. aparines, the similarity of rDNA-ITS sequences of P. aconiti was 94%. The similarity of 28 S rDNA D1/D2 sequences of P. aconiti was 97% compared that with P. pulveracea, P. ficariae and P. bulbocapni. Conclusion: The results of morphological identification of downy mildew pathogen separated from A. carmichaeli are consistent with those from molecular identification (rDNA-ITS and 28 S rDNA D1/D2 sequences) and the pathogen of Aconitum downy mildew should be P. aconiti. Therefore, rDNA-ITS and 28 S rDNA D1/D2 sequences constructed in this paper can be used to identify downy mildew pathogen from Aconitum carmichaeli Debx.