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This article in CS

  1. Vol. 22 No. 3, p. 657-660
    Received: Mar 19, 1981

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A Hybrid Between Agropyron trachycaulum and A. desertorum1

  1. K. V. Napier and
  2. P. D. Walton2



An interspecific hybrid between Agropyron trachycaulum (2n = 28) as female and A. desertorum (2n = 28) was obtained by controlled crossing in a greenhouse, followed by embryo culture. The purposes of this study were to describe the morphology and cytology of this new hybrid. Most vegetative and spike characteristics of the hybrid were intermediate between those of the parent species. The allopolyploid A. trachycaulum, designated SSHH, regularly formed 14 bivalents at meiotic Metaphase I, and A. desertorum, designated CCCC, behaved as an autotetraploid, with an average configuration of 8.4II and 2.8IV. The hybrid, 2n = 28, represented by the formula SHCC provided a new genome combination and genetic background in which to study pairing of the three genomes. An average of 9.24I, 8.62II, 0.47III and 0.031V per cell was observed with a range of 6 to 12 bivalents (47% closed). Seven bivalents were attributed to autosyndetic pairing of A. desertorum genomes. Trivalents may have been formed from S chromosomes associated with a CC bivalent. Additional bivalents must have been formed by associations between the S and H genomes of A. trachycaulum. This indicates that these chromosomes may be sufficiently homologous (homoeologous) to enable pairing to occur in certain genetic backgrounds.

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