Hybridization between diploid Centaurea pseudophrygia and tetraploid C. jacea (Asteraceae): the role of mixed pollination, unreduced gametes, and mentor effects

摘要: We studied hybridization between the diploid Centaurea pseudophrygia and tetraploid C. jacea by performing crossing experiments screening natural populations using flow cytometry. The confirm that species exhibit strong reproductive isolation. Interspecific hybrids were formed at a low frequency, including triploids (originating from reduced gametes) tetraploids (involving unreduced gametes of diploids). In contrast, almost absent among seeds adult plants mixed offspring experimental pollinations with mixture pollen both ploidy levels. found pollination is an important mechanism for preventing different levels sustaining reproduction tetraploids. A mentor effect (induced selfing in presence levels) was observed diploids tetraploids, reinforcing isolation cytotypes. Higher (pentaploid, hexaploid) involving identified. Notably, pentaploids discovered first time sect. Jacea. © 2011 Linnean Society London, Biological Journal Society, 2011, 104, 93–106.