Homoeologous Chromosome Pairing: Frequency Differences in Inbred and Intraspecific Hybrid Polyploid Ferns

Science  01 Dec 1978:
Vol. 202, Issue 4371, pp. 982-984
DOI: 10.1126/science.202.4371.982


The homosporous fern Ceratopteris thalictroides (Parkeriaceae) has evolved a polyploid genetic system that serves to store and release genetic variability in spite of self-fertilization and Mendelian homozygosity. This is demonstrated by the segregation of a gametophyte mutant within two inbred tetraploid lines and in their intraspecific hybrid. The segregation behavior can be explained by a model involving a duplicated locus and regular homoeologous chromosome pairing. Homoeologous pairing occurs at low levels in the inbred lines and at a high level in the hybrid, indicating intraspecific differences in chromosome pairing affinities.