Identification of Intergenomic Translocations Involving Wheat, Hordeum Vulgare and Hordeum Chilense Chromosomes by FISH

Abstract

Interspecific and intergeneric hybrids in the Triticeae are valuable for transfers of genes from one species to another and to extend the range of genetic variation available to plant breeders. For a long time, one goal of cereal breeders has been the production of amphiploids between wheat and barley in order to combine desirable features from both species. Since the first success achieved by KRUSE (1973) crossing cultivated barley and wheat (Hordeum vulgure x Triticum aestivum, T. turgidum, and T, monococcum), numerous hybrid combinations between the two genera have been reported (see FEDAK 1992, for a review), mainly involving non-cultivated Hordeum species. Among these, H. chilense is a wild barley from Chile and Argentina with high cross-ability with other Triticeae genera (FEDAK 1992). Crosses between H. chilense and diploid, tetraploid and hexaploid wheats give rise to tetraploid, hexaploid and octoploid tritordeums, respectively (MARTIN and SANCHEZ-MONGE LAGUNA 1982;MARTIN et al. 1987; CABRERA and M A R T~N 1991).Hexaploid tritordeum (2n = 6x = 42, AABBHChHCh) is a subject for a breeding program with the goal of creating a new cereal crop (MART~N 1988) and in this way we intend to incorporate the genetic variability of cultivated barley, H. vulgare, into the gene pool of tritordeum. For achieving this objective hybrids between barley and tritordeum at the three ploidy levels have been produced (MARTIN et al. 1995). Another different approach is to cross barley addition lines in T. aestivum with hexaploid tritordeum. We present here the identification by fluorescence in situ hybridization (FISH) of intergenomic translocations involving barley, wheat and H. chilense chromosomes obtained from crosses between barley addition lines in hexaploid wheat and tritordeum. MATERIALS AND METHODSRoot tips were collected from germinating seeds of advanced lines from the cross between three disomic chromosome addition lines for chromosomes 2H", 3H", and 4H" of barley (Hordeum vulgure) in Triticum aestivum cv. Chinese Spring (CS) (ISLAM et al. 1975) and hexaploid tritordeum (2n = 6x = 42, AABBHchHCh). These root tips were pre-treated for 3 h in a 0.05 YO colchicine solution at 25°C and fixed in 100 % ethanol-acetic acid, 3: 1 (v/v), for at least a week at room temperature. Root tips were then stained in acetocarmine for 3 min, scraped out the meristems and squashed in 45 Y acetic acid on ethanol-cleaned slides. The preparations were frozen in liquid nitrogen, the cover slips subsequently removed and then dehydrated for 3 min each in 70 YO and absolute ethanol at room temperature. The air-dried slides were stored at 4°C until used. Probes used were total genomic H. vulgure DNA and total genomic H. chilense DNA and they were labelled by nick translation with biotin-1 1-dUTP (Roche Corporate, Basel, Switzerland) and digoxigenin-1 1-dUTP (Roche Corporate), respectively. Both probes were mixed to a final concentration of 5 ng/p1 in the hybridization mixture. The in situ hybridization protocol was performed according to CABR...

Development and cytogenetic characterisation of a double goat grass-barley chromosome substitution in tritordeum

“…The use of total genomic DNA as species-specific probes resulted in an efficient procedure to distinguish between different genomes in the material analysed. FISH, including the multi-colour combinations, has been successfully used for wheat and its relatives Prieto et al, 2001). In this study, the quality of hybridization was highly satisfactory and clearly differentiated between wheat, H. vulgare and H. chilense genomes without the use of blocking DNA.…”

“…Genomic in situ hybridisation (GISH) and fluorescent in situ hybridisation (FISH) are well-established and highly efficient techniques for chromosome identification. In situ hybridisation readily distinguishes H. chilense and H. vulgare chromosomes from those of wheat Prieto et al, 2001) and permits the assessment of the physical size of introgressed segments.…”

Cytogenetics of <i>Hordeum chilense:</i> current status and considerations with reference to breeding

“…The remaining translocation with no transgene integration was a Robertsonian translocation (Barro et al, 2003 (Fig. 2g) were most frequent, followed by wheat-H. chilense and wheat-H. vulgare intergeneric translocations (Prieto et al, 2001). These lines may be useful for introgressing characters of interest from H. vulgare into tritordeum.…”

Detection of alien genetic introgressions in bread wheat using dot-blot genomic hybridisation

“…The use of molecular markers combined with in situ hybridisation is very useful for finding exogenous genetic introgressions (Schwarzacher et al 1989; Calderón et al 2012; Zhao et al 2013), but the exogenous chromosome fragment needs to be previously identified and well characterised in order to choose specific molecular markers that will allow the alien sequence to be unequivocally distinguished from the equivalent chromosome region in wheat, which can sometimes be difficult. In addition, in situ hybridisation enables the determination of the exact chromosomal compositions in the descendence of genetic crosses between wheat and related species (Prieto et al 2001). However, although in situ hybridisation is an enormously informative genetic approach, it requires high expertise and is time consuming, making the cytogenetic approach expensive when there is a need to analyse hundreds of plants resulting from genetic crosses.…”