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Poster: Molecular & Cellular Plant-Microbe Interactions: MPMI


Exploring the Monilinia vaccinii-corymbosi-blueberry pathosystem for the discovery of genes governing host-specificity.
K. BANSAL (1), J. Rollins (1) (1) University of Florida, U.S.A.

Monilinia vaccinii-corymbosi, a Sclerotiniaceae member, causes mummy berry disease on blueberries. Primary infection of vegetative tissues is caused by ascospores and secondary infection of flowers is caused by conidia. Fruit infection is highly specific as conidial germ tubes enter the host through flowers. Conidia germinate on stigma, traverse the stylar canal to colonize developing ovules, converting fruit into a mummy. To understand the underlying genetics of this specificity, we are developing standardized tools for generating inoculum, visualizing the course of infection, and collecting infected materials for transcriptomic analysis. A comparison of culture media and temperature conditions demonstrated that four day old cultures of M. vaccinii-corymbosi isolate RL1 (Mvc-RL1) grown on oatmeal agar medium, in the dark, at 22°C followed by a low temperature shift (15°C) induced sporulation most abundantly after 24 hours. For characterization of the gynoecium infection process, a protoplast-mediated genetic transformation system was utilized to produce constitutive GFP-expressing Mvc-RL1 strains. Floral inoculation of Southern High Bush variety Legacy with conidia of GFP-Mvc-RL1 documented germinating conidia and the course of hyphae traversing the stylar canal. Using these tools, floral infections will be utilized for comparison with uninoculated flowers for transcriptomic analysis and identification of genes underlying host specificity in M. vaccinii-corymbosi.