Detection and Molecular Phylogenetic-Morphometric Characterization of Rhizoctonia tuliparum, Causal Agent of Gray Bulb Rot of Tulips and Bulbous Iris

Journal of Fungi

Annie DeBauw¹  Katie Coats¹  Gary Chastagner¹  Daniel P. Roberts²  Adnan Ismaiel²  Dilip K. Lakshman² 

[1] Department of Plant Pathology, Washington State University Research & Extension Center, 2606 West Pioneer, Puyallup, WA 98371, USA;Sustainable Agricultural Systems Laboratory, USDA-ARS, 10300 Baltimore Avenue, Beltsville, MD 20705, USA;

关键词: Sclerotium tuliparum;    Ceratobasidium;    quantitative PCR;    soil-borne pathogen;    sclerotia;    ITS2 secondary structure;   

DOI  :  10.3390/jof8020163

来源: DOAJ

【 摘 要 】

Gray bulb rot of tulips and bulbous iris is caused by the soil-borne fungal pathogen, Rhizoctonia tuliparum (Rtul). Sclerotia present in infected bulbs, as well as overwintering sclerotia in soil and field debris, are the primary sources of infection. A method for accurate and sensitive detection of Rtul from soil and infected bulbs, and estimation of inoculum threshold levels, is needed for the management of disease caused by this pathogen. We designed a unique set of primers targeting the ITS2 region of the Rtul genome and developed a highly sensitive quantitative PCR (qPCR)-based method for Rtul identification using these primers, where the threshold of detection was approximately 1 fg Rtul DNA. The assay was more sensitive with sclerotia collected from the field (natural) than with those grown in the lab, and more sensitive with natural-light than natural-dark sclerotia. Also, the detection method was more sensitive when sclerotia were extracted from soil than from bulb tissue. The qPCR method was highly specific, as no PCR amplification was detected when genomic DNA from 62 non-Rtul Rhizoctonia isolates from a wide range of anastomosis groups were tested. To understand the evolutionary relationships and genomic diversity of Rtul, we performed phylogenetics of the ITS1-5.8S-ITS2 region and ITS2-molecular morphometric characterization (MMC) of Rtul isolates. The three Rtul isolates whose ITS sequences were available in GenBank formed a distinct phylogenetic clade with Ceratobasidium anceps as the nearest relative. Furthermore, MMC analysis revealed genetic divergence among these three Rtul isolates.

【 授权许可】

Unknown