THE MAT-ALLELE OF PODOSPORA-ANSERINA CONTAINS 3 REGULATORY GENES REQUIRED FOR THE DEVELOPMENT OF FERTILIZED FEMALE ORGANS

In the filamentous fungus Podospora anserina, mating type is specified by a single locus with two alternate alleles, termed mat- and mat+. A previous study has shown that the mat- sequence consists of 3.7 kb an d contains a single gene relevant to the sexual cycle. This gene, call ed FPR1, encodes a protein with a HMG DNA-binding domain and is requir ed for fertilization and for the development of the fertilized fruitin g body. The mat-sequence, which is 4.7 kb in length, displays a more c omplex structure. We present here the characterization of two genes, c alled SMR1 and SMR2, which are present in the mat- allele along with t he FMR1 gene. FMR1, whose role in the sexual cycle has been already pa rtially described, encodes a protein with an alpha 1-domain and was sh own to control fertilization. We demonstrate that these three genes ar e required for the developmental events that occur in the female organ after fertilization. The additional role of FMR1 requires a region of unknown function that is distinct from the alpha 1-domain. SMR1 encod es a protein with a putative acidic/hydrophobic alpha-helix, which has been proposed to be a feature common to transcriptional activators. T he protein sequence deduced from SMR2 contains an HMG motif suggesting that it is a transcription factor.