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Apolinarska B. 1996. Tetraploid rye with wheat genetic material. In: Plant Cytogenetics (Maluszynska J. ed.) Silesian Univ. Katowice: 206–209. Apolinarska B. 2003a. Chromosome pairing

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Durum wheat ( Triticum turgidum L., 2 n = 4 x = 28; AABB genomes) is an important cereal crop widely used for human consumption. Fusarium head blight (FHB), or scab, caused by the fungus Fusarium graminearum Schwabe, is a serious disease of durum wheat. Current durum cultivars have very little or no FHB resistance. A wild relative, diploid wheatgrass Lophopyrum elongatum (Host) Á. Löve (2 n = 2 x = 14; EE genome) is an excellent source of resistance. By crossing durum wheat with L. elongatum we produced F 1 hybrids that were male sterile. By backcrossing the F1 hybrids to the durum parent, followed by selfing, we obtained several fertile hybrid derivatives with FHB resistance. We isolated a disomic addition line (2 n = 28 + 2) with a pair of L. elongatum chromosomes. This alien addition line is meiotically regular and hence reproductively stable. The addition line is FHB-resistant with a mean infection of 6.5%, while the parental durum has 80% infection. Using various biochemical and molecular techniques — fluorescent genomic in situ hybridization (fl-GISH) and chromosome-specific markers — we have shown that the extra chromosome involved is 1E of L. elongatum . This is the first time that FHB resistance has been discovered on chromosome 1E.

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371 380 Fedak, G. : 1997. Increased homoeologous chromosome pairing in Hordeum vulgare × Triticum aestivum hybrids. Nature, 266: 529

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. Genetic induction of chromosomal structural changes of alien chromosomes in common wheat 40 43 Fedak, G. 1977: Increased homoeologous chromosome pairing

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In this study, we employed electron microscopy to investigate the cytogenetic and embryologic mechanisms of parthenogenesis induced in the 1BL/1RS male sterile lines of wheat. Analysis of the root tips and acid polyacrylamide gel electrophoresis indicated that all of the male sterile lines and their maintainer lines were 1BL/1RS translocation lines, whereas the restorer lines were non-1BL/1RS translocation lines. Furthermore, the chromosomes of 1BL/1RS wheat lines with T. aestivum cytoplasm and Aegilops cytoplasm (include Ae. kotschyi, Ae. ventricosa, Ae. variabilis) paired abnormally at different rates during meiotic metaphase I (MMI). The translocated segment size of the 1RS chromosome and the specific nuclear–alloplasm interaction impaired the pairing of homologous chromosome in the background of the specific Aegilops cytoplasm at MMI. In addition, the frequency of abnormal chromosomal pairing was directly affected by the frequency of haploid production induced by parthenogenesis. The results of this study provide significant insights into the mechanism of parthenogenesis, which is probably due to the abnormal fertilization of synergid cells in alloplasmic 1BL/1RS wheat.

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Biotechnology. Kurata, N. and Omura, T. (1978): Karyotype analysis in rice. I. New method for identifying all Chromosome Pairs. - Jap. J. Genet. 53 : 251

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Aegilops sharonensis (Sharon goatgrass) is a valuable source of novel high molecular weight glutenin subunits, resistance to wheat rust, powdery mildew, and insect pests. In this study, we successfully hybridized Ae. sharonensis as the pollen parent to common wheat and obtained backcross derivatives. F1 intergeneric hybrids were verified using morphological observation and cytological and molecular analyses. The phenotypes of the hybrid plants were intermediate between Ae. sharonensis and common wheat. Observations of mitosis in root tip cells and meiosis in pollen mother cells revealed that the F1 hybrids possessed 28 chromosomes. Chromosome pairing at metaphase I of the pollen mother cells in the F1 hybrid plants was low, and the meiotic configuration was 25.94 I + 1.03 II (rod). Two pairs of primers were screened out from 150 simple sequence repeat markers, and primer WMC634 was used to identified the presence of the genome of Ae. sharonensis. Sequencing results showed that the F1 hybrids contained the Ssh genome of Ae. sharonensis. The sodium dodecyl sulfate polyacrylamide gel electrophoresis profile showed that the alien high molecular weight glutenin subunits of Ae. sharonensis were transferred into the F1 and backcross derivatives. The new wheat-Ae. sharonensis derivatives that we have produced will be valuable for increasing resistance to various diseases of wheat and for improving the quality of bread wheat.

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Farooq, S., Iqbal, N., Shah, T.M. 1990. Intergenetic hybridization for wheat improvement. III. Genetic variation in Triticum species affecting homoeologous chromosome pairing. Cereal Res. Comm. 18 :233

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Apolinarska, B. 2003b. Chromosome pairing in tetraploid rye with monosomic-substitution wheat chromosomes. J. Appl. Genet. 44 :119–128. Apolinarska B. Chromosome pairing in tetraploid

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Colas, I., Shaw, P., Prieto, P., Wanous, M., Spielmeyer, W., Mago, R., Moore, G. 2008. Effective chromosome pairing requires chromatin remodelling at the onset of meiosis. Proc. Natl. Acad. Sci. 105 :6075

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