Talk by M. Soledade C. Pedras – University of Copenhagen

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Talk by M. Soledade C. Pedras

Of Crucifers and Fungi, the Winters of our Discontent

Plants and their microbial invaders are involved in an arms race that continues to cause sustainability issues for agriculture. The use of fungicides and pesticides to prevent crop losses causes pollution and health hazards that make these agricultural practices unacceptable. Therefore, continuing efforts to develop methodologies that allow agriculture to become sustainable are critical. To devise sustainable methods to prevent and deter cruciferous pathogens, their molecular interaction with crucifers (Brassicaceae), both cultivated and wild, is under intense investigation.

Crucifers (e.g. canola, mustard, cauliflower, broccoli, turnip, thale cress) produce complex blends of secondary metabolites with diverse ecological roles, which include self-protection against microbial pathogens, pests and other sorts of stress, whereas their fungal pathogens produce phytotoxic metabolites and macromolecules that
facilitate plant invasion. Phytoalexins are natural products involved in elicited plant defence pathways operating against plant pathogens and abiotic stress.

The chemodiversity of phytoalexins correlates with the biodiversity of their sources. For example, within crucifers, cultivated Brassica species produce phytoalexins such as brassinin, brassilexin, and rutalexin, whereas wild crucifer species such as Arabidopsis thaliana and Thellungiella salsuginea produce camalexin and wasalexins, respectively. An overview of the phytoalexins and phytotoxins from crucifers and their fungi and
corresponding biosynthetic pathways will be presented.

Although some of these phytoalexins are detoxified by fungal pathogens, these fungal detoxifications can be stopped. That is, inhibitors (paldoxins) of these transformations could protect plants by boosting their natural chemical defenses and prevent pathogen growth. The fundamental aspects and challenges of such a strategy to treat plant fungal diseases will be presented. Knowledge of new phytoalexins and their biosynthetic and degradation pathways will facilitate the identification of plant defence genes and the breeding of plants producing more potent antifungal defenses.

About Prof. Pedras: M. Soledade C. Pedras is Professor of Chemistry at the University of Saskatchewan and Canada Research Chair in Bioorganic and Agricultural Chemistry. She has a B.Sc., Licentiate from the University of Porto, Portugal and did her PhD at the University of Alberta, Canada.

Her research group at the University of Saskatchewan is using bioorganic, biochemical and biological techniques to understand economically important diseases of cruciferous oilseeds (e.g. canola, rapeseed, and mustard), vegetables (e.g. rutabaga, broccoli, cauliflower, and turnip), and condiments (e.g. mustard and wasabi). In particular, the interaction of crucifers with blackleg, blackspot, root rot, stem rot, white rot, and white rust fungi is being investigated.

Reviews:
Pedras, M. S. C.; Yaya, E. E. 2015. Plant chemical defenses: Are all constitutive antimicrobial metabolites phytoanticipins? Natural Products Communications, 9, 209-216.

Pedras, M. S. C. 2014. Chemistry and biology of the cruciferous phytoalexins brassinin and cyclobrassinin. The Natural Products Journal, 4, 166-172.

Pedras, M. S. C. 2013. Metabolism and detoxification of phytoalexins from crucifers and application to the control of fungal plant pathogens. Biotechnology of Crucifers, S. Gupta, ed., Springer, 151-171.

Pedras, M. S. C.; Yaya, E. E.; Glawischnig, E. 2011. The phytoalexins from cultivated and wild crucifers: Chemistry and biology. Natural Product Reports, 28, 1381-1405.

Pedras, M. S. C.; Yu, Y. 2009. Phytotoxins, elicitors and other secondary metabolites from phytopathogenic blackleg fungi: structure, phytotoxicity and biosynthesis. Natural Product Communications, 4, 1291-1304.