Identification of gene-controlled steps of ascospore development in Podospora anserina

Abstract

Twenty-seven genes necessary for sporulation were identified in Podospora anserina. The structural characteristics of these sporulation-deficient mutants ( spo) compared to wild type were examined by light and electron microscopy. Several features of the interplay of sporulation events emerge from this study: (1) Any disturbance of the postmeiotic mitosis (PMM) spindle arrangement leads to abnormal sporulation. (2) Initiation and development of the double ascospore-delimiting membranes are independent from nuclear division and spindle plaques, but their lack leads to the occurrence of supernumerary PMM. In wild type, PMM are inhibited from the end of the first PMM until ascospore maturity. (3) Most mutants have a pleiotropic phenotype suggesting that some altered functions involved in the sporulation process are also involved in vegetative growth and/or meiosis. The order and dependence of the respective gene functions of some of the mutations were determined by the behavior of double-mutant strains. The data obtained indicate that spo mutants are useful tools for probing the genetic control of developmental events.