P-656 - Mycoparasitism of Hansfordia pulvinata against tomato leaf mold is facilitated by red light via phytochrome

   Cladosporium fulvum (syn. Fulvia fulva) is a well-studied filamentous pathogen that causes leaf mold of tomato. This fungus enters leaves through stomata and colonizes the apoplastic space. C. fulvum frequently evolves new races that overcome tomato Cf resistance cultivars. Additionally, this pathogen has developed tolerance to chemical fungicides, highlighting the need for sustainable alternatives like biocontrol agents. Coincidentally, we found that mycoparasitic fungus Hansfordia pulvinata growing over C. fulvum legion on leaves and disease
progression was inhibited on these leaves. As this fungal interaction occurs on leaves, we focused on the role of light in mycoparasitism of H. pulvinata.

　When H. pulvinata and C. fulvum were incubated under different light conditions, sporulation was induced in both fungi under red light and in the dark conditions. The mycoparasitic activity of H. pulvinata against C. fulvum was facilitated only under red light (630 nm) irradiation. In plants, a photoreceptor phytochrome is sensitive to light in the red and far-red region. We identified a phytochrome gene HpFph1 in genome sequence of H. pulvinata, and obtained HpFph1 protein via expression system in E. coli and affinity purification. The maximum absorption wavelength of HpFph1 protein measured by a spectrophotometer was 635.5 nm, which was almost identical to the red wavelength (630 nm) that facilitates the mycoparasitic activity of H. pulvinata. These results suggested that H. pulvinata parasitizes C. fulvum through the phytochrome HpFph1 during the day when red light is abundant.