Reduced metaphase I associations between the short arms of homoeologous chromosomes in a Hordeum vulgare L. � H. bulbosum L. diploid hybrid influences the frequency of recombinant progeny

Abstract

Hordeum vulgare (cultivated barley) x H. bulbosum (bulbous barley grass) hybrids have been used to obtain disease-resistant recombinant lines (RLs). The RLs contain chromatin transferred from the wild species mostly onto the long arms of recipient barley chromosomes. To determine whether differences in meiotic metaphase I (MI) associations between the long and short arms of homologous chromosomes can account for the preponderance of introgressions on the long arms, we carried out fluorescent in situ hybridisation on MI chromosome preparations obtained from pollen mother cells of a diploid interspecific hybrid. By using various probes, we established that MI associations between the long arms occurred more frequently than between the short arms for the five chromosomes tested.

The Effect of Homoeologous Meiotic Pairing in Tetraploid <b><i>Hordeum bulbosum</i></b> L. × <b><i>H. vulgare</i></b> L. Hybrids on Alien Introgressions in Offspring

“…This observation agrees with the work of Pickering et al [2006a] who investigated the chromosome pairing frequency of 2 diploid Hv × Hb hybrids. In contrast to our results regarding the frequency of Hv -Hb pairing of long and short arms of particular chromosomes, Pickering et al [2004] observed differences only in short-arm pairing. Frequencies of long-arm pairing were similar for Hv chromosomes 1H, 2H, 4H, 5H, and 6H.…”

“…Fig. 1e, f) as reported by Pickering et al [2004]. The chromosome 1Hv was identified by weak proximal FISH signals on the short arm (online suppl.…”

“…In meiotic cells, the Hv -Hb pairing configuration 5H was detected by a strong signal on the short arm of 5Hb ( Fig. 2 a, b, e, f) as described by Pickering et al [2004].…”

The use of cytogenetic tools for studies in the crop-to-wild gene transfer scenario

“…FISH with selected probes has also allowed identification of allosyndetic MI pairing for specific chromosomes (Pickering et al, 2004). This is highlighted by the study of Cuadrado et al (1997) who individually recognized the whole chromosome complement of wheat !…”

“…The whole chromosome complement of some crop species can be individualized by sequential FISH using appropriate sets of selected repeated DNA probes (Cuadrado et al, 1997;Irigoyen et al, 2002). However, only a few chromosomes are marked in most instances (e.g., Pickering et al, 2004). Combination of repeated and genomic probes has been demonstrated to be a great improvement in identification of particular chromosomes and chromosomal segments in multigenomic materials (Dong et al, 2001;Maluszynska and Hasterok, 2005;Cifuentes et al, 2006;Herrera et al, 2007) ( Figs.…”