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  • Author or Editor: M. Molnár-Láng x
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The multicolour genomic in situ hybridization (mcGISH) method was improved in order to visualize the U b and M b genomes of Aegilops biuncialis Vis. (2n=4x=28, U b U b M b M b ). Hybridization probes prepared from the diploid U and M genome donors, Ae. umbellulata and Ae. comosa , resulted in clear hybridization signals on the U and M chromosomes in Ae. biuncialis . The random primed labelling method made it possible to decrease the blocking ratio to 1:30. McGISH allowed the simultaneous discrimination of individual Ae. biuncialis genomes and wheat chromosomes in γ-irradiated Triticum aestivum-Ae. biuncialis amphiploids (2n=70; AABBDDU b U b M b M b ). Dicentric chromosomes, terminal and interstitial translocations and centric fusions were detected in the irradiated generation. The irradiation-induced wheat- Ae. biuncialis intergenomic translocations will facilitate the successful introgression of useful agronomic traits into bread wheat.

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Several molecular markers have been reported for the detection of the 1RS chromosome arm. The aim of the present experiments was to study the reliability and reproducibility of six molecular markers specific to the 1RS rye chromosome (GPI, Bmac213, 5S, IAG95, SCM9 and RMS13) in distinguishing between wheat genotypes with and without the 1BL.1RS or 1AL.1RS translocations. In the course of the analysis, PCR products of the expected size were obtained with all the markers, which were found to give a reliable indication of the presence of the 1RS chromosome arm in the wheat genome.

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The present study was focused on the selection of S. cereale cultivars of different geographic origin showing polymorphism detectable by fluorescent in situ hybridization on their 1RS chromosome arms. One perennial and four annual genotypes were tested. FISH was carried out with the DNA probes pSc119.2 and (AAC) 5 . The pSc119.2 probe gave hybridization signals different from that of the rye ‘Petkus’ on the 1RS arms of all five rye cultivars examined. Differences were manifested mainly in the intensity of the labelling, but the complete lack of FISH signals and double signals were also observed.

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Six different 1RS-specific molecular markers (RMS13, Bmac213, GPI, 5S, SCM9, IAG95) were tested in twenty rye cultivars of various origin. The aim of the experiments was to choose rye cultivars which give polymorphic PCR products with these 1RS-specific markers compared to the wheat cultivar Mv Magdaléna, which contains the 1BL.1RS translocation. The polymorphic rye cultivars can be presumed to differ from the 1BL.1RS translocation originating from the Petkus rye cultivar and will hopefully carry effective resistance genes which can be incorporated into the 1BL.1RS translocation in wheat. Twenty rye cultivars (at least two plants per cultivar) were analysed with these markers. Of fifty-two rye samples analysed, three plants were found to be polymorphic, one (Kisvárdai Alacsony from Hungary), for the 5S marker, one (Kriszta from Hungary) for the RMS13 marker and one (Porto from Portugal) for the SCM9 marker. The polymorphic plants were grown to maturity in the phytotron.

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Fluorescence in situ hybridization (FISH) is the most versatile and accurate molecular cytogenetic technique for determining euchromatic-heterochromatic boundaries and the locations of repetitive and single-copy DNA sequences and of chromosome-specific BAC clones on chromosomes. The combination of cytogenetic and genetic methods yields a highresolution physical map. FISH allows direct mapping of specific DNA sequences inside the cell (interphase nuclei), along meiotic pachytene chromosomes and isolated chromatin (DNA fibres). The increased sensitivity of the technique and its ability to detect gene locations provide a powerful research tool for genetic and pre-breeding studies. FISH-based physical mapping plays an important role and is increasingly used for studies at the cytological level on the chromatin organization that controls gene expression and regulation. The present minireview describes some of the benefits of alternative FISH-based techniques and their application for studying plant chromosomes and genomes.

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One way of incorporating useful traits from Aegilops biuncialis (2n=4x=28, U b U b M b M b ) into wheat ( Triticum aestivum L. 2n=6x=42, AABBDD) is to develop first addition then translocation lines. The 2M b , 3M b , 7M b , 3U b , 5U b and 5U b /6U b wheat- Ae. biuncialis addition lines were produced in Martonvásár. To facilitate the exact identification of the addition lines, it was necessary to analyse the fluorescence in situ hybridisation patterns of the parental wheat genotype, Ae. biuncialis and its diploid progenitors ( Ae. umbellulata 2n=2x=14, UU and Ae. comosa 2n=2x=14, MM). The great genetic variability of the Aegilops species causes polymorphism in the fluorescence in situ hybridisation (FISH) patterns of the individual chromosomes. Due to the high level of FISH polymorphism, it is advisable to confirm the identification of the Ae. biuncialis chromosomes with the help of molecular (microsatellite, SSR) markers, so 119 wheat SSR markers were tested on Aegilops biuncialis , on Ae. geniculata (2n=4x=28, U g U g M g M g ), on five wheat- Ae. biuncialis addition lines (2M b , 3M b , 7M b , 3U b , 5U b ) and on an addition series of wheat- Ae. geniculata in order to select SSR markers specific to the U and M genomes of Ae. biuncialis and Ae. geniculata .

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The safety of wheat production in Hungary requires the propagation of droughttolerant cultivars because of the regular occurrence of water deficiency. Hybridization between related species makes it possible to transfer desirable traits from one species to another. Introgression lines developed from wheat/barley hybrids were investigated together with the parental wheat and barley cultivars to determine how the added barley chromosome (segment) influences drought tolerance in wheat. The plants were grown in the field at the UP Georgikon Faculty, Keszthely. Sowing and harvest were done by hand. Half the length of the 12 m rows was covered with a plastic rain shelter on 2 nd April (EC: 30–31) to protect the plants from rain, resulting in a 163 mm difference in water supplies between the control (not covered) and stressed (covered) treatments. Data were obtained for anthesis and maturity date, plant height, root/shoot ratio, leaf water potential, grain yield and grain yield components. The plants adapted to water deficiency by increasing the root/shoot ratio and decreasing the water potential and the duration of grain filling. The grain yield was reduced by 12%, averaged over the genotypes, mainly due to a decrease in the number of spikes per plant.

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The aim of the present study was to test the efficiency of gamma irradiation in inducing translocations between wheat and barley genomes using addition lines. The Martonvásári 9 kr1-Igri disomic addition set, previously produced in Martonvásár, was irradiated with gamma rays. The pattern of irradiation-induced intergenomic chromosome rearrangements was analysed in the mutagenized (M0) generation by genomic in situ hybridization (GISH). Centric fusions and a wide variety of reciprocal, terminal and interstitial translocations were frequently induced. The intergeneric translocations produced here are expected to be stabilized in later backcross progenies as a set of introgression lines carrying few but distinct rearrangements.

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The photosynthetic responses induced by NaCl were investigated in the 7H Asakaze komugi/Manas wheat/barley addition line developed in the Agricultural Research Institute, Martonvásár, Hungary, in the wheat (Triticum aestivum L.) cv. Asakaze komugi (Akom) and wheat line Martonvásári 9 kr1 (Mv9kr1) and in the barley (Hordeum vulgare L.) cv. Manas. An increase in the NaCl concentration of the nutrient solution to 200 mmol L−1 resulted in considerable stomatal closure and a decreased net CO2 assimilation rate (A) in the wheat genotypes, while the changes in these parameters were less significant for barley and the 7H addition line. Parallel with this, a relatively high non-stomatal limitation (L m) of A was observed in wheat genotypes, which was not significant in Manas or the wheat-barley addition line at this level of salt stress. At severe stress (300 mM L−1 NaCl concentration) A and stomatal conductance were strongly inhibited in all the genotypes examined; however, L m was less significant in the addition line and its parental wheat genotype. These preliminary results suggest that the 7H Akom/Manas addition line might be a good candidate for improving the salt tolerance of wheat in the future, and encourage further detailed physiological analysis of this addition line.

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