摘要：Many species, including most flowering plants, are polyploid, possessing multiple genomes. During polyploidisation, fertility is preserved via the evolution of mechanisms to control the behaviour of these multiple genomes during meiosis. On the polyploidisation of wheat, the major meiotic gene
ZIP4 duplicated and diverged, with the resulting new gene
TaZIP4-B2 being inserted into chromosome 5B. Previous studies showed that this
TaZIP4-B2 promotes pairing and synapsis between wheat homologous chromosomes, whilst suppressing crossover between related (homoeologous) chromosomes. Moreover, in wheat, the presence of
TaZIP4-B2 preserves up to 50% of grain number. The present study exploits a ‘separation-of-function’ wheat
Tazip4-B2 mutant named
zip4-ph1d, in which the
Tazip4-B2 copy still promotes correct pairing and synapsis between homologues (resulting in the same pollen profile and fertility normally found in wild type wheat), but which also allows crossover between the related chromosomes in wheat haploids of this mutant. This suggests an improved utility for the new
zip4-ph1d mutant line during wheat breeding, compared to the previously described CRISPR
Tazip4-B2 and
ph1 mutant lines. The results also reveal that loss of suppression of homoeologous crossover between wheat chromosomes does not in itself reduce wheat fertility when promotion of homologous pairing and synapsis by
TaZIP4-B2 is preserved.
