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Hybrids of South American Elymus agropyroides with Agropyron caespitosum, Agropyron subsecundum, and Sitanion hystrix

Douglas R. Dewey
Botanical Gazette
Vol. 131, No. 3 (Sep., 1970), pp. 210-216
Stable URL: http://www.jstor.org/stable/2473569
Page Count: 7
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Hybrids of South American Elymus agropyroides with Agropyron caespitosum, Agropyron subsecundum, and Sitanion hystrix
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Abstract

South American Elymus agropyroides Presl, 2n = 28, behaved cytologically as an alloploid with more-than-normal meiotic irregularity. Five unemasculated spikes of Asian Agropyron caespitosum Koch, 2n = 14, pollinated by E. agropyroides, yielded 12 viable hybrid seeds. The hybrids, 2n = 21, were completely sterile and bore a close resemblance to A. caespitosum. Chromosome pairing in 135 hybrid cells at metaphase I averaged 11.62I, 4.54II, and 0.11III. One E agropyroides genome appears to be partially homologous with the A. caespitosum genome. Natural hybrids with North American A. subsecundum (Link) Hitchc., 2n = 28, and Sitanion hystrix (Nutt.) J. G. Smith, 2n = 28, occurred in open-pollination progenies of E. agropyroides. The natural hybrids were morphologically intermediate between their putative parents. The E. agropyroides x A. subsecundum hybrid averaged 3.44I, 10.79II, 0.33III, and 0.33IV to VIII in 58 metaphase-I cells; and the E. agropyroides x S. hystrix hybrids averaged 5.08I, 11.40II, and 0.04III in 96 cells. All hybrids were completely sterile. Both genomes of E. agropyroides, A. subsecundum, and S. hystrix apparently have considerable homologies. These three tetraploids share the basic S genome of diploid A. caespitosum and A. spicatum (Pursh) Scribn. & Smith, and their second genome may have come from Hordeum.

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