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Bridging Ploidy Differences in Crested Wheatgrass with Hexaploid ✕ Diploid Hybrids 1
Author(s) -
Asay K. H.,
Dewey D. R.
Publication year - 1979
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1979.0011183x001900040021x
Subject(s) - hybrid , biology , ploidy , agropyron cristatum , germplasm , botany , polyploid , meiosis , genetics , gene
Hybrids between hexaploid (2n = 6x = 42) and diploid (2n = 2x = 14) Agropyron cristatum (L.) Gaertn. were crossed with the 6x and 2x parents, with colchicine‐induced tetrapinid (C4x) A. cristatum (2n = 4x = 28), and with natural tetraploid (N4x) A. desertorum (Fisch. ex. Link) Schult. (2n = 4x = 28). Fertility and chromosomepairing relationships were studied in the triploid, tetraploid, and pentaploid progenies to evaluate ways that 6x‐2x hybrids could be used to combine the genetic resources of the three ploidy levels into one germplasm pool. Cytological data demonstrated that genomes from e three ploidy levels were similar, differing only by structural rearrangements. The (6x‐2x) ✕ C4x tetraploids were the most fertile hybrids, with an average seed set of 53 seeds per spike compared with 21, 9, and 0.2 seeds per spike for the (6x‐2x) ✕ N4x, (6x‐2x) ✕ 6x, and (6x‐2x) ✕ 2x hybrids, respectively. Some (6x‐2x) ✕ N4x hybrid tetraploids, with germplasm of all three ploidy levels represented, were fertile enough to be used directly in a breeding program. The (6x‐2x) ✕ C4x hybrid tetraploids should have merit in crosses with (6x‐2x) ✕ N4x hybrids and N4x tetraploids to produce breeding populations with germplasm from the three ploidy levels. The sterility and meiotic irregularity of the (6x‐2x) ✕ 6x triploid hybrids and (6x‐2x) ✕ 6x pentaploid hybrids seriously limit their direct use in breeding schemes.