It is believed that unreduced gametes with
somatic chromosome numbers play a predominant
role in natural polyploidization. Allohexaploid bread
wheat originated from spontaneous hybridization of
Triticum turgidum L. with Aegilops tauschii Coss.
Unreduced gametes originating via meiotic restitution,
including first-division restitution (FDR) and
single-division meiosis (SDM), are well documented
in triploid F1 hybrids of T. turgidum with diploid Ae.
tauschii (genomic constitution ABD, usually with 21
univalents in meiotic metaphase I). In this study, two
T. turgidum lines known to carry genes for meiotic
restitution were crossed to tetraploid Ae. tauschii.
The resulting F1 hybrids (genomes ABDD), had
seven pairs of homologous chromosomes and regularly
formed 14 univalents and seven bivalents at
metaphase I. Neither FDR nor SDM were observed.
The distribution of chromosome numbers among
progeny obtained by self pollination and a backcross
to T. turgidum showed the absence of unreduced
gametes. These results suggest that high homologous
pairing interfered with meiotic restitution and the
formation of unreduced gametes. This may be related
to asynchronous movement during meiosis between
paired and unpaired chromosomes or to uneven
distribution of chromosomes in anaphases, resulting
in nonviable gametes.
The research has been published on Euphytica (2010) 175:323–329
DOI 10.1007/s10681-010-0173-4
Chun-Jie Wang • Lian-Quan Zhang •
Shou-Fen Dai • You-Liang Zheng •
Huai-Gang Zhang • Deng-Cai Liu