A synthetic hexaploid (2n = 42) oat from the cross of Avena strigosa (2n = 14) and domesticated A. magna (2n = 28) |
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Authors: | Gideon Ladizinsky |
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Institution: | (1) Faculty of Agriculture, The Hebrew University, P.O. Box 12, Rehovot, 76100, Israel; |
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Abstract: | A synthetic hexaploid oat was produced by chromosome doubling of a sterile triploid hybrid between cultivated Avena strigosa (2n = 14) cv. Saia and a domesticated form of A. magna (2n = 28). The synthetic hexaploid was intermediate between its parents in panicle shape and lemma color, similar to the
tetraploid parent in spikelet structure, and to the diploid parent in having a single, albeit partially shriveled seed per
spikelet, and low protein content. By the third generation, plants with yellowish lemmas, mostly two seeds per spikelet and
better filled grains had been selected. Rust resistance of the diploid parent was retained in the synthetic hexaploid, but
not tolerance to barley yellow dwarf virus disease (BYDV). Chromosome associations at meiosis in the triploid hybrid was low,
with over 60% of them being univalents. Bivalent association was the rule in the synthetic hexaploid with an occasional one
or two quadrivalents. Regular meiosis with 21 bivalents was observed in further generations. The preferential pairing of homologous
chromosomes in the synthetic hexaploid was probably contributed by the A. strigosa genome which exhibits this tendency in artificial allopolyploid situations. Selection of yellow lemma color and two seeds
per spikelet suggests that the genes controlling these traits are located on the chromosomes involved in quadrivalents in
the synthetic hexaploid. The potential and limitations of utilizing the synthetic hexaploid in oat research and breeding are
briefly discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | Avena chromosome doubling interspecific hybridization preferential pairing |
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