Abstract:

The purpose of the study is to identify the species and host range of powdery mildew on Polygonum persicaria L. by microscopic observation and phylogenetic relationship analysis, and to provide a reasonable basis for the control of powdery mildew. The powdery mildew on P. persicaria was used as test material. The conidia, ascus and ascospore were morphologically observed and described by microscopic observation. Genome DNA of the pathogen was extracted by kit method and amplified by ITS. The microscopic observation showed that the conidia of powdery mildew on P. persicaria were columnar. The asci were dark brown, mostly aggregated or near aggregated, and most of them were oblate spherical. Most of the asci were in various irregular oval shapes, containing 2 to 4 oval ascospores. Combined with other powdery mildew base sequence alignment and the analysis of genetic relationship, the powdery mildew on P. persicaria was confirmed to have the closest genetic relationship with Polygonum aviculare (LC328322.1) and Polygonum erectum (KX826856.1) from GeneBank, the sequence similarity was up to 99%. It was preliminarily determined that the pathogen of P. persicaria powdery mildew belonged to the same genus with these two species.

Key words: Polygonum persicaria L., powdery mildew, microscopic observation, ITS, phylogenetic analysis