Fluorescent AFLP technique was employed to investigate polymorphisms between Triticum aestivum cv. Chinese Spring (CS) and T. spelta var. duhamelianum (Splt). Of 2322 bands generated by 32 primer combinations, 286 were polymorphic between CS and SpIt. The polymorphism rate (0.123) was lower than that previously revealed by RFLP (0.174). Aneuploid analysis of those bands detected in CS indicated unequal distribution of AFLP markers within the wheat genome. Polymorphism. survey was also made in two CS derived gametocidal (Gc) lines having a Gc gene from Aegilops speltoides or Ae. sharonensis. Gc lines showed gain or loss of bands compared to CS.

A. Kawabe, S. Nasuda, and N. T. Miyashita (Grad. Schl. Agr., Kyoto Univ.)
An analysis of codon usage in common wheat (Triticum aestivum): a possibility of natural selection on synonymous substitution

Codon usage in 223 wheat nuclear genes was analyzed. Codon bias varied among genes. The frequency distribution of codon bias in wheat was similar to those of maize and barley. Codon bias was correlated with GC content at the third position of codon. Genes which showed high codon bias in wheat had high codon bias in maize and barley. Between wheat and maize, codon bias was significantly correlated with the number of synonymous substitutions per site i. e., high biased genes had low synonymous substitutions. This result suggested that synonymous substitutions were not selectively neutral in the Poaceae.

Getachew Belay (Fac. Agr., Gifu Univ.)
C-band polymorphism and chromosomal rearrangements in Ethiopian tetraploid wheats

C-band polymorphism was studied in seven tetraploid (2n=3D4x=3D28) wheat (Triticum turgidum L.) landraces of Ethiopian. origin, and an attempt was made to localize chromosomal breakpoints in five of them that carry one reciprocal translocation each, relative to the variety "Senatore CappelIi" (SC). Most chromosomes showed C-banding variation, which was not associated with spike morphology or collection locality. None of the genotypes showed a similar C-banding pattern to SC for chromosome arms 3BL, 5AL and 5BL. Unusual bands or banding patterns were observed on 2AS, 7AL, 5BL and 7BS. Generally, unequivocal localization of translocation breakpoints by C-banding alone proved difficult. Nevertheless, it is plausible that most of the translocations have non-centromeric breakpoints.

Kaz. Noda¹, Y. Amano², and T. Fukase³ (¹Res. Inst. Biores., Okayama Univ., ²Kitami Agr. Exp. Stn., ³Tokachi Agr. Exp Stn.)
Premature a-amylase production in de-embryonated seeds of wheat

Preharvest sprouting and seeds with high a-amylase activity without germination have been observed every three years in Japan and on average, 20 percent or more of the seeds are classified as out of the standard grade. Two periods during seed development are responsive to these phenomena. 1) Frequent rainfalls during the ripe stage of seeds. 2) Humid and cool temperature in the maturing stage (between yellow ripe and full ripe). In respect to premature a-amylase production, de-embryonated half seeds of some wheat lines showed to have a potential to synthesize alpha-amylase when imbibed.

H. Tsujimoto, T. Yamada, and T. Sasakuma (Kihara Inst Biol. Res., Yokohama City Univ.)
Leymus racemosus chromosome addition lines of common wheat (preliminary report)

Leymus racemosus (2n=4x=28, NNXX) was crossed as male with common wheat (Triticum aestivum) cultivar "Chinese Spring" (abbrev. CS). The hybrid was rescued by embryo culture and treated with colchicine for chromosome doubling. The amphidiploid was further crossed with CS, and a plant with genomes AABBDDNX was obtained. The offspring (26 plants) by the cross between the octoploid and CS carried from 41 to 52 chromosomes. Most of the L. racemosus chromosomes were distinguished from each other and from common wheat chromosomes by C-banding. Since all of the alien chromosomes appeared in the offspring, complete set of addition lines will be possibly bred.

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