Open AccessAllozyme segregation and inter‐cytotype reproductive barriers in the polyploid complex Centaurea jacea
Author(s) -
Hardy Olivier J.,
De Loose Marc,
Vekemans Xavier,
Meerts Pierre
Publication year - 2001
Publication title -
heredity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.441
H-Index - 118
eISSN - 1365-2540
pISSN - 0018-067X
DOI - 10.1046/j.1365-2540.2001.00862.x
Subject(s) - biology , selfing , ploidy , pollen , polyploid , gene flow , locus (genetics) , outcrossing , botany , evolutionary biology , genetics , population , genetic variation , gene , demography , sociology
In eastern Belgium, diploid and tetraploid knapweeds ( Centaurea jacea L. s. l. ) show a parapatric distribution with a contact zone. To compare the success of inter‐ and intra‐cytotype crosses, and to investigate the pattern of allozyme segregation, controlled crosses involving plants from this contact zone were performed. Polysomic inheritance at two loci was observed in tetraploids, suggesting an autopolyploid origin. Two crosses allowed the detection of double reduction events in tetraploids at one locus, but no such event was detected among the 217 progenies. Null alleles were detected in tetraploids at two loci. Both cytotypes were highly self‐incompatible. Inter‐cytotype crosses were much less successful than intra‐cytotype crosses in terms of seed set (five‐fold reduction) and germination rates (three‐fold reduction), suggesting a ‘triploid block’ effect. Progenies from inter‐cytotype crosses most often had the maternal cytotype and resulted from selfing or pollen contamination. However, six triploids were detected. The significance of these results for the understanding of the geographical distribution of the cytotypes and inter‐cytotype gene flow is discussed.