THE DYNAMICS OF GYNODIOECY IN PLANTAGO-LANCEOLATA L .2. MODE OF ACTION AND FREQUENCIES OF RESTORER-ALLELES

Male fertility in Plantago lanceolata is controlled by the interaction of cytoplasmic and nuclear genes. Different cytoplasmic male sterilit y (CMS) types can be either: male sterile or hermaphrodite, depending on the presence of nuclear restorer alleles. In three CMS types of P. lanceolata (CMSI, CMSIIa, and CMSIIb) the number of loci involved in m ale fertility restoration was determined. In each CMS type, male ferti lity was restored by multiple genes with either dominant or-recessive action and capable either of restoring male fertility independently or in interaction with each other (epistasis). Restorer allele frequenci es for CMSI, CMSIIa and CMSIIb, were determined by crossing hermaphrod ites with ''standard'' male steriles. Segregation of male steriles vs. non-male steriles was used to estimate overall restorer allele freque ncy. The frequency of restorer alleles was different for the CMS types : restorer alleles for CMSI were less frequent than for CMSIIa and CMS IIb. On the basis of the frequencies of male steriles and the CMS type s an ''expected'' restorer allele frequency could be calculated. The c orrelation between estimated and expected restorer allele frequency wa s significant.