关键词: 芍药, 红斑病, 病原鉴定, 链格孢属, rDNA-ITS

Abstract: Red spot has been one of the most serious diseases in herbaceous peony production. Identification of the pathogen causing the disease is necessary for the determination of effective treatment options. In the present study，firstly，the fungi were isolated and purified from the infected leaves and the pathogenicity was detected by artificial inoculation. Then the morphological characteristics and rDNA-ITS sequence of the pathogens causing red spot disease was studied. The results demonstrated that two kinds of suspected fungi，A and B，were isolated from the disease-infected samples，with the isolation ratio of 4.8︰1. Both fungi were further confirmed pathogenic and therefore determined as the pathogens. The morphological characteristics revealed that these two pathogens were Alternaria alternate and A. tenuissima，which was validated by further rDNA-ITS analysis. ITS1-5.8S rDNA-ITS2 sequences of pathogen A and pathogen B were respectively highly homogenic with those of KF380822.1 and HM467832.1 in GenBank database，hence they were respectively identified as A. alternate and A. tenuissima. The sequences of these two pathogens have been submitted to GenBank，and the accession numbers are KR912224 and KR912225. Based on the above results，it was concluded that red spot diseaseon herbaceous peony in Shandong province was caused by both A. alternate and A. tenuissima.

Key words: Paeonia lactiflora, red spot, pathogen identification, Alternaria；rDNA-ITS