First report of pink root rot caused by <i>Setophoma (Pyrenochaeta) terrestris</i> on canola

Abstract

Diseased canola plants which failed to produce pods and were shorter than healthy plants in the same field were submitted to the Alberta Plant Health Laboratory in September 2016. The predominant symptom on infected plants was root rot, resembling a pink root rot. The objective of this study was to confirm the occurrence of canola pink root rot in Alberta. Two of the fungal strains isolated from symptomatic root samples were subjected to DNA barcoding that targeted three genomic regions, namely the internal transcribed spacer (ITS) region, the translation elongation factor-1α gene (EF1) and the β-tubulin gene. By similarity search (BlastN) using the resultant sequences as queries against GenBank accession sequences, both isolates were identified as Setophoma terrestris. Experiments were conducted to fulfil Koch’s postulates to demonstrate that this fungal species is a pathogen of canola. After inoculation, the two strains could cause pink root rot on canola. The fungal strains were re-isolated from the inoculated canola and their identity confirmed as S. terrestris. This is the first report of pink root rot on canola and on any Brassica host in the world.