Abstract Detail

Mycological Section

Hambleton, Sarah [1], Eggertson, Quinn [1], Liu, Miao [1].

The rust pathogens of Rubus in Canada – identification, nomenclature and DNA-barcoding.

Species in the genus Rubus are perennial herbs, shrubs or training vines found abundantly in north temperate regions. Several are cultivated for their edible fruits (especially red raspberry, black raspberry and blackberry) and many more are valued as a food source by foragers. They contribute to wildlife habitat in hedgerows and as understory plants but in some areas, introduced species have become invasive and require active pest management strategies. The use of rust fungi for biological control is one option being studied. Ten species in four rust genera, Gymnoconia, Kuehneola, Phragmidium and Pucciniastrum, have been documented as pathogens of Rubus in Canada. Three of these genera include species flagged by other countries for regulatory reasons or as invasive species causing diseases on Rubus and other host plants. As part of a large-scale DNA-barcoding project, representative specimens held in the National Mycological Herbarium in Ottawa (DAOM) were examined and sampled to generate DNA barcode sequences of both rust (ITS2 and partial 28S) and host (partial rbcL). The objective was to evaluate historical identifications and nomenclature and to accurately document host-pest associations. The species selected for sequencing in this study overlapped very little with those already represented in the public sequence database GenBank. DNA barcodes were generated for 20 additional species of Phragmidium and Pucciniastrum on Rubus, including five known in Canada. For the rusts, these data provided diagnostic resolution at the species level. Based on the topology of a preliminary tree, a few specimens labelled as Phragmidium violaceum, Pucciniastrum americanum and Pucciniastrum arcticum were re-determined as Kuehneola uredinis. The sequences for 19 representative specimens of Phragmidium rubi-idaei, the cause of raspberry yellow rust, separated into two groups suggesting two distinct taxa are involved. Gymnoconia peckiana and Gymnoconia nitens are treated as synonyms by some authors but our data supported these species as two taxa. Preliminary trees of the host DNA barcodes provided an overview of species groups at the sub-generic level, as was expected for the rbcL gene, but for species level resolution more variable gene regions are required.

1 - Agriculture and Agri-Food Canada, Biodiversity (Mycology), 960 Carling Avenue, Ottawa, ON, K1A 0C6, Canada

Keywords:
plant diseases
Molecular identification
DNA barcoding
taxonomy
Raspberry.

Presentation Type: Oral Paper:Papers for Sections
Session: 64
Location: Salon 1/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 11:15 AM
Number: 64005
Abstract ID:887
Candidate for Awards:None