B. cinerea deploys an enoyl-reductase to detoxify scopoletin and related coumarins by reducing them to their melilotic acid derivatives.
Phytopathogenic fungi must contend with host immune responses to successfully colonize plant tissues. These responses include the production of heterogenous antimicrobial compounds (phytoalexins), which plants deploy to intoxicate infecting microbes. Among these phytoalexins are the coumarins, a family of aromatic lactones widely present in dicotyledons. The fungus Botrytis cinerea is a necrotroph that infects a plethora of dicotyledonous hosts, causing considerable losses in the produce and cut flower industries. As a well-adapted pathogen, B. cinerea is capable of detoxifying or expelling numerous phytoalexins (i.e. rishitin, capsidiol, resveratrol, camalexin, and glucosinolates) to support its virulence. However, unlike the coumarins, these phytoalexins are phylogenetically restricted to a limited number of agriculturally important B. cinerea hosts. Here, we demonstrate that B. cinerea deploys an enoyl-reductase, BCIN14g01070 (Bcsaf1), to detoxify scopoletin and related coumarins by reducing them to their melilotic acid derivatives. We further show that Bcsaf1 is conserved amongst numerous members of the family Sclerotiniacea, and that an ortholog from another notorious phytopathogen, Sclerotinia sclerotiorum, possesses similar coumarin-degradation capacity. Finally, we construct ?Bcsaf1 mutants, which display compromised coumarin-degradation capacity, reduced virulence on Helianthus annuus (sunflower) and Nicotiana tabacum (tobacco), and enhances susceptibility to fungitoxic coumarins. Together, these studies identify Bcsaf1 as an important virulence factor that counters coumarin-phytoalexins to support B. cinerea infection.
Phytopathogenic fungi must contend with host immune responses to successfully colonize plant tissues. These responses include the production of heterogenous antimicrobial compounds (phytoalexins), which plants deploy to intoxicate infecting microbes. Among these phytoalexins are the coumarins, a family of aromatic lactones widely present in dicotyledons. The fungus Botrytis cinerea is a necrotroph that infects a plethora of dicotyledonous hosts, causing considerable losses in the produce and cut flower industries. As a well-adapted pathogen, B. cinerea is capable of detoxifying or expelling numerous phytoalexins (i.e. rishitin, capsidiol, resveratrol, camalexin, and glucosinolates) to support its virulence. However, unlike the coumarins, these phytoalexins are phylogenetically restricted to a limited number of agriculturally important B. cinerea hosts. Here, we demonstrate that B. cinerea deploys an enoyl-reductase, BCIN14g01070 (Bcsaf1), to detoxify scopoletin and related coumarins by reducing them to their melilotic acid derivatives. We further show that Bcsaf1 is conserved amongst numerous members of the family Sclerotiniacea, and that an ortholog from another notorious phytopathogen, Sclerotinia sclerotiorum, possesses similar coumarin-degradation capacity. Finally, we construct ?Bcsaf1 mutants, which display compromised coumarin-degradation capacity, reduced virulence on Helianthus annuus (sunflower) and Nicotiana tabacum (tobacco), and enhances susceptibility to fungitoxic coumarins. Together, these studies identify Bcsaf1 as an important virulence factor that counters coumarin-phytoalexins to support B. cinerea infection.