Apothecial Production, Compatibility and Sex in Botryotinia squamosa

Abstract

SUMMARYApothecia of Botryotinia squamosa were produced in compatible matings on a wheat macerate medium or on sand culture under programmed changes of temperature and light. Sclerotial development, dormancy, spermatization, and fructification occurred in approximately 3 months. Apothecial initials did not expand and form mature apothecia in the absence of light or when exposed to incandescent or fluorescent irradiation alone, but expanded normally when exposed to a combination of these light sources.Compatibility in B. squamosa is controlled by a single locus with two alleles, A and a. Wild-type isolates were hermaphroditic, self-sterile, and cross-fertile. They formed a sclerotial stroma, partially enveloped by a pigmented rind, from which apothecia arose when spermatized by isolates of opposite mating type. Of 742 random monoascosporic isolates from four crosses, 353 were A and 389 were a. Of 106 monoconidial isolates from Orange County, New York, 49 were A and 57 a.Wild-type isolates were intergroup fertile but some sclerotial isolates of compatible matings did not produce apothecial initials. This suggests that a factor(s) other than A and a also controls apothecial ontogeny. Strains deficient in their ability to produce apothecial intials were either sclerotial or asclerotial and functioned as males.Structures resembling apothecial initials were produced on sclerotia treated with a crude cell-free extract of homogenized mycelia and/or sclerotia of the same or opposite mating type. Conidia from aborted apothecial initials were of the maternal mating type. Interspecific crosses between Botryotinia squamosa and B. fuckeliana were unsuccessful.