Molecular cytogenetic characterization of parental genomes in the partial amphidiploid Triticum aestivum x Thinopyrum ponticum

Abstract

The wheat line PF 839197 and six hybrid derivatives from a cross between PF 839197 and Thinopyrum ponticum were cytologically characterized by fluorescent in situ hybridization (FISH). Probes for the 5S and 45S rDNA genes (pTa794 and pTa71, respectively), a highly repetitive rye sequence (pSc119.2), the synthetic oligonucleotide (AAG) 5 , and total genomic DNA from Th. ponticum and rye were used. In the wheat line, a 1RS.1BL translocation was revealed by the labeling patterns produced with pSc119.2 and (AAG) 5 , and confirmed by genomic in situ hybridization (GISH) using rye genomic DNA as a probe. Analyses of partial amphiploids confirmed previous results indicating mitotic instability, with a tendency to stabilize at 2n = 42 or 56. GISH with Th. ponticum genomic DNA showed that in one hybrid derivative, with lower chromosome numbers (2n = 42-45), chromosomes were not labeled, whereas in the hybrids with 2n = 48-56 up to 14 chromosomes were labeled. These data suggest that the original chromosome set of these hybrids was 2n = 56, and that chromosomes from both genomes were lost by mitotic instability. FISH using the rDNA probes and GISH with Thinopyrum genomic DNA suggested that cells with 2n = 56 contained an entire wheat genome plus two monoploid chromosome sets of Th. ponticum.

Chromosome and genome composition of a Triticum × Thinopyrum hybrid by classical and molecular cytogenetic techniques

“…The pSc119.2 probe hybridized to several species of the tribe Triticeae (Heslop-Harrison 2000), being one of them Thinopyrum (Brasileiro-Vidal et al 2005;Sepsi et al 2008). Although Kosina and Heslop-Harrison (1996) found that the composition of repetitive DNA sequences was extremely similar in the E and J genomes of Thinopyrum, Lapitan et al (1987) discriminated between both genomes using the pSc119.2 probe.…”

“…A volume containing 100 ng of the labeled probe was then added to 30 ll of this hybridization mixture for each slide. In some cases, a blocking procedure (Anamthawat-Jónsson et al 1990;Bennett 1995) was applied by adding 30 parts of unlabeled total genome DNA from wheat to 1 part of labeled total DNA probe from Thinopyrum, based on the optimum proportion of 30:1, as established by Brasileiro-Vidal et al (2005). The hybridization mixture was denatured for 15 min at 75°C, loaded onto the slide preparation, and covered with a plastic coverslip.…”

Cytomixis-like chromosomes/chromatin elimination from pollen mother cells (PMCs) in wheat-rye allopolyploids

“…There are also few evidences for complete uniparental chromosome elimination in hybrids containing closely related genomes [21,33,76] or remotely related genomes [10, 36, 37, 49-51, 67, 85]. Biparental chromosome loss is less frequent, but it was noted for example in Triticum aestivum x Thinopyrum ponticum hybrids [9]. Following interspecific hybridization between Hordeum vulgare and H. bulbosum the H. bulbosum chromosomes are selectively eliminated during mitotic divisions of the developing embryo.…”

Review Genomic in situ hybridization in plants

“…This translocation of the chromosome arm 1RS of rye in cultivars of wheat positively affects its performance and confers resistance against insects and the attack of pathogens (Brasileiro-Vidal et al, 2005). In the wheat line ZT, it was possible to determine the presence of two resistance genes deriving from Thinopyrum intermedium: one involving the translocation of chromosome 7D, called T7DS.7DL-7Ai#1L, carrying the Bdv2 gene that confers resistance to BYDV-PAV, and the chromosome 2 pair, called 2Ai#z, which also carried the resistance gene to BYDV-PAV (Jahier et al, 2009).…”