Cytogenetic and protein studies in hexaploid wheat

Giemsa N-banding is a method that facilitates the identification of chromosomes with the use of the light microscope. The heterochromatic regions which contain repetitive DNA sequences are stained. A distinctive banding pattern for the stained chromosomes is produced. Five of the 21 wheat (Triticum aestivum) chromosomes do not display N-bands; chromosomes 1A, 3D, 4D, 5D and 6D. Somatic chromosomes were identified and compared for the \u27Chinese Spring\u27, \u27Nap Hal\u27 and \u27Atlas 66\u27 cultivars. The overall banding patterns were similar for the three cultivars. In the A genome, chromosomes 6A and 7A showed dissimilar banding patterns. The B genome had the greatest number and dissimilarity of bands. The D-genome chromosomes of the three cultivars were very similar. An investigation was under to determine the chromosomes involved in the heterozygous reciprocal translocation in the Atlas 66 cultivar. Atlas 66 was crossed to a set of Chinese Spring double ditelosomic plants. F$\sb1$ plants from 19 crosses produced a meiotic configuration of 18 bivalents, a translocation chain of 4 chromosomes, a trivalent containing the two telochromosomes and a standard chromosome. It was concluded that the homoeologous chromosomes 2A and 2D were involved in the translocation because the F$\sb1$ configurations were either 19 bivalents, one unpaired telochromosome and a chain consisting of three whole chromosomes and the other telochromosome or 20 bivalents and a trivalent containing the two telochromosomes. This suggests Atlas 66 gametes contained only one translocated chromosome. The reverse-phase high-performance liquid chromatography (RP-HPLC) method was used to characterize gliadin proteins from four F$\sb4$-derived high-protein bulk populations and their parental lines. Gliadins are one of two major seed storage proteins in wheat flour. Each population had at least one high-protein parent. Seed was analyzed for protein quality by the mixograph, and grain and flour protein by Kjeldahl nitrogen. Chromatogram peaks showed a lack of strong, consistent correlations with the quality parameters, but some trends were seen. Similarity coefficients, used to quantify the resemblance between progeny and parents for gliadin composition, were weak indicators of progeny end-use quality, although some expected effects were indicated