Detection of intergenomic chromosome rearrangements in irradiated Triticum aestivum - Aegilops biuncialis amphiploids by multicolour genomic in situ hybridization

摘要

The frequency and pattern of irradiation-induced intergenomic chromosome rearrangements were analysed in the mutagenized (Mo) and the first selfed (M 1 ) generations of Triticum aestivum L. – Aegilops biuncialis Vis. amphiploids (2n = 70, AABBDDUbUbMbMb) by multicolour genomic in situ hybridization (mcGISH). mcGISH allowed the simultaneous discrimination of individual Ae. biuncialis genomes and wheat chromosomes. Dicentric chromosomes, fragments, and terminal translocations were most frequently induced by y-irradiation, but centric fusions and internal exchanges were also more abundant in the treated plants than in control amphiploids. Rearrangements involving the U b genome (Ub-type aberrations) were more frequent than those involving the M b genome (Mb-type aberrations). This irradiation sensitivity of the Ub chromosomes was attributed to their centromeric or near-centromeric regions, since U b-type centric fusions were significantly more abundant than Mb-type centric fusions at all irradiation doses. Dicentrics completely disappeared, but centric fusions and translocations were well transmitted from Mo to M i . Identification of specific chromosomes involved in some rearrangements was attempted by sequential fluorescence in situ hybridization with a mix of repeated DNA probes and GISH on the same slide. The irradiated amphiploids formed fewer seeds than untreated plants, but normal levels of fertility were recovered in their offspring. The irradiation-induced wheat – Ae. biuncialis intergenomic translocations will facilitate the successful introgression of drought tolerance and other alien traits into bread wheat.