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  • Author or Editor: É. Szakács x
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The relationship between ultrastructural changes in the anthers caused by cold pretreatment and the haploid induction capacity of different maize genotypes was investigated. The degeneration of the tapetal cells appears to be genotype-dependent, but the extent of the degeneration is not correlated with the androgenetic ability of the given genotype. Based on the stainability of the cytoplasm, two microspore types were found. The results suggest that the “dense” microspores take part in pollen embryogenesis.

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Colchicine is a plant alkaloid, known for thousands of years and currently used widely for the doubling of the genome in plant and animal cells due to its antimitotic effect. The aim of the present experiments was to develop stable autodiploid pollen grains in vitro in diploid lines of rye (Secale cereale L.) and barley (Hordeum vulgare L.) and to use these in intra- and interspecific crosses. Spikelet cultures of one rye and one barley variety were subjected to colchicine treatment in different stages of development and under differing in vitro conditions. Exposure to colchicine led to a drastic reduction both in the number of fertile pollen grains and in the percentage seed-setting, which was only observed in cultures inoculated in the early binuclear microspore stage. On medium containing colchicine the seed-setting percentage was 1.6% for barley and 0.1% for rye. Flow cytometry and root tip analysis revealed that all the progeny barley plants were diploid, while in the case of rye one was tetraploid, indicating that the egg cell may also be diploidised by colchicine treatment.

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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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The 4H(4D) wheat/barley substitution line was crossed with the ‘Chinese Spring’ ph1b mutant genotype in order to induce wheat-barley homoeologous recombinations. F3 and F4 seeds of the 4H(4D) × ‘Chinese Spring’ ph1b mutant cross were analysed using genomic in situ hybridization, and a Robertsonian translocation was detected in monosomic form. Disomic centric fusions were selected among the self-fertilized progenies. The presence of the long arm of 4H was confirmed with SSR markers. The long arm of the 5D wheat chromosome in the Robertsonian translocation was identified using fluorescent in situ hybridization with the help of three DNA probes: pSc119.2, Afa family and pTa71. The wheat/barley centric fusion was identified as a 4HL.5DL translocation. This line exhibited supernumerary spikelet character, but the number of seeds/plant did not increase. The 4HL.5DL centric fusion line is suitable genetic material to study the expression of genes located on 4HL in a wheat genetic background.

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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 aim of the experiments was to develop translocation lines by inducing homoeologous chromosome pairing in a 4H(4D) wheat-barley substitution line previously developed in Martonvásár. It was hoped to incorporate various segments of the barley 4H chromosome from the 4H(4D) substitution into wheat. Observations were made on the frequency with which wheat-barley translocations appeared in the F 2 progeny grains from a cross between the line CO4-1, which carries the Ph suppressor gene from Aegilops speltoides and thus induces a high level of homoeologous chromosome pairing, and the 4H(4D) wheat-barley substitution line, and on which chromosome segments were involved in the translocations. The translocations were identified by means of genomic in situ hybridisation. Of the 117 plants examined, three (2.4 %) were found to contain translocations. A total of four translocations were observed, as one plant contained two different translocations. The translocations consisted of one centric fusion, two dicentric translocations and one acrocentric chromosome. Plants carrying translocations were raised in the phytotron and the selection of homozygous translocation lines was commenced from the F 3 progeny grains.

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