Nutrient Medium Developed for the in vitro Demonstration of Sexual Reproduction by Cryphonectriaparasitica
Steven Jakobi, Amy Werner, Mark Double

Abstract
Eighteen agar-based nutrient media were evaluated for their ability to support sexual reproduction (perithecia and viable ascospore formation) by the chestnut blight fungus, Cryphonectriaparasitica. Preliminary screening of each medium involved pairings of four sexually compatible isolates. If a medium appeared to support ascospore production, conidia (asexual spores) of 10 sexually compatible isolates of the pathogen were paired in 29 different combinations. Isolates were either recipients of conidia from a sexually compatible strain, or acted in reverse as the "male" donor of conidia. The most successful preparation was Leonian agar amended with 1 percent "light" coconut milk. Twenty-five of 29 pairings yielded ascopores in as few as 13 d (average 29 d) after establishment of crosses. Four isolates failed to develop ascospores when they were recipients of sexually compatible conidia, but were successful as spermatizing agents. These isolates most likely exhibited female sterility.

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