Spontaneous and CRISPR/Cas9-induced mutation of the osmosensor histidine kinase of the canola pathogen Leptosphaeria maculans

Alexander Idnurm*, Andrew S. Urquhart, Dinesh R. Vummadi, Steven Chang, Angela P. Van de Wouw, Francisco J. López-Ruiz

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

56 Citations (Scopus)
14 Downloads (Pure)


Background: The dicarboximide fungicide iprodione has been used to combat blackleg disease of canola (Brassica napus), caused by the fungus Leptosphaeria maculans. For example, in Australia the fungicide was used in the late 1990s but is no longer registered for use against blackleg disease, and therefore the impact of iprodione on L. maculans has not been investigated. 

Results: Resistance to iprodione emerged spontaneously under in vitro conditions at high frequency. A basis for this resistance was mutations in the hos1 gene that encodes a predicted osmosensing histidine kinase. While loss of the homologous histidine kinase in some fungi has deleterious effects on growth and pathogenicity, the L. maculans strains with the hos1 gene mutated had reduced growth under high salt conditions, but were still capable of causing lesions on B. napus. The relative ease to isolate mutants with resistance to iprodione provided a method to develop and then optimize a CRISPR/Cas9 system for gene disruptions in L. maculans, a species that until now has been particularly difficult to manipulate by targeted gene disruptions. 

Conclusions: While iprodione is initially effective against L. maculans in vitro, resistance emerges easily and these strains are able to cause lesions on canola. This may explain the limited efficacy of iprodione in field conditions. Iprodione resistance, such as through mutations of genes like hos1, provides an effective direction for the optimization of gene disruption techniques.

Original languageEnglish
Article number12
Pages (from-to)1-12
Number of pages12
JournalFungal Biology and Biotechnology
Issue number1
Publication statusPublished - 16 Dec 2017
Externally publishedYes

Bibliographical note

Copyright the Author(s) 2017. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.


  • Agrobacterium-mediated transformation
  • Canola
  • Gene editing
  • HOG pathway


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