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CYTOGENETICS OF AGROPYRON FERGANENSE AND ITS HYBRIDS WITH SIX SPECIES OF AGROPYRON, ELYMUS, AND SITANION
Author(s) -
Dewey Douglas R.
Publication year - 1981
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1981.tb12381.x
Subject(s) - biology , agropyron , hybrid , ploidy , elymus , meiosis , botany , polyploid , agropyron cristatum , genetics , poaceae , gene
Meiosis and mode of reproduction are described in Agropyron ferganense Drob., a perennial forage grass from Central Asia. This species is diploid (2 n = 14); it exhibits normal meiosis and reproduces by cross‐pollination. Hybrids were produced between A. ferganense and six species with known genome formulas: 1) North American A. spicatum (Pursh) Scribn. & Smith, an SS diploid (2 n = 14), 2) Middle Eastern A. libanoticum Hack., an SS diploid (2 n = 14), 3) North American A. dasystachyum (Hook.) Scribn., an SSHH tetraploid (2 n = 28), 4) Eurasian A. caninum (L.) Beauv., an SSHH tetraploid (2 n = 28), 5) North American Sitation hystrix (Nutt.) J. G. Smith, an SSHH tetraploid (2 n = 28), and 6) South American Elymus patagonicus Speg., an SSHHHH hexaploid (2 n = 42). Almost complete chromosome pairing in the A. ferganense x A. spicatum and A. libanoticum hybrids demonstrated that A. fergenanse is an SS diploid, but it is genetically isolated from the other SS diploids because of high sterility in the F 1 hybrids. S‐genome diploids form a network of species that extend from the Middle East through Central Asia to western North America. Frequent occurrence of seven univalents and seven bivalents at metaphase I in the triploid hybrids of A. ferganense x A. dasystachyum, A. caninum and S. hystrix was consistent with the proposed genome formulas of SS for A. ferganense , SSHH for the three tetraploid species, and SSH for the hybrids. Chromosome pairing was highly variable in the A. ferganense x E. patagonicus hybrids; however, some cells had almost complete bivalent pairing, an expected observation in an SSHH hybrid from a cross between an SS diploid ( A. ferganense ) and an SSHHHH hexaploid ( E. patagonicus ) . Various options were considered concerning the appropriate generic classification of the S‐genome diploids, which are now commonly placed in Agropyron. The inclusion of these species in the genus Eiytrigia , as advocated by some Soviet taxonomists, appears to be a reasonable decision.