Segmental Allopolyploidy in Tetraploid and Hexaploid Agropyron Species of the Crested Wheatgrass Complex (Section Agropyron)¹

Abstract

T HE crested wheatgrass complex is one of the least understood groups of taxa belonging to Agropyron. Biosystematic studies are presently being made in order to better understand this difficult species complex (17). 3 Beetle (1) states that the true answers to nomenclatural puzzles usually lie in the homeland of the species involved, and pending more detailed field studies in regions where these species are native, one would seem well advised to accept the concensus of the best Old World analysis available. The authors believe that Nevski's (14) classification suits this purpose best. Nevski listed 13 different species in the section Agropyron of Agropyron Gaertn. and described their morphology. These species are A.

Meiotic behaviour in natural diploid, tetraploid, and commercial diploid crested wheatgrass

“…So, the homology between the homologous chromosomes seems strong enough to synapse in the three crested wheatgrasses. These findings and those of other studies are in agreement with the hypothesis arguing that tetraploid crested wheatgrass is basically a natural autotetraploid (Dewey 1961b(Dewey , 1984Ray et al 1994) or allopolyploid not far from autoploidy (Schulz-Schaeffer et al 1963). Thus, the polyploid material of crested wheatgrass resembled an autotetraploid in its meiotic behaviour at diakinesis and MI.…”

A fertile amphiploid between diploid wheat (Triticum tauschii) and crested wheatgrass (Agropyron cristatum)

“…The two genomes in this case should be considered different, P1 and P2, one of them being derived from the other by reciprocal translocations. Schulz-Schaeffer et al (1963) proposed for an hexaploid A. cristatum accession, PI223323, a segmental origin throughout reciprocal translocations; one of the genomes differs from the others by 3 interchanges with 2 sets of homologues in common. The tetraploid accession we used to synthesise the amphiploid reported here could have the same genome structure but at the tetraploid level.…”

Meiotic Pairing in a Trigeneric Hybrid Triticum Tauschii-Agropyron Cristatum-Hordeum Chilense

“…cristatum plant used as male parental was a segmental allotetraploid (STEBBINS 1947). The major segmental changes from both genomes were attributed to reciprocal translocations, as SCHULZ-SCHAEFFER et al (1963) found in a hexaploid population of this species. Most probably the reason of the low survival rate of embryos found in the present experiment was the high production of unbalanced gametes of the T. tauschii-A.…”