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Reproduction in Crested Wheatgrass Pentaploids 1
Author(s) -
Dewey Douglas R.
Publication year - 1974
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/cropsci1974.0011183x001400060028x
Subject(s) - biology , hybrid , ploidy , polyploid , chromosome , loss of heterozygosity , agropyron cristatum , botany , metaphase , reproduction , cytogenetics , genetics , gene , allele
Pentaploid, 2n=35, crested wheatgrasses [ Agropyron cristatum (L.) Gaertn.] and related taxa., were derived by crossing natural and induced tetraploids, 2n=28, with hexaploids, 2n=42. The pentaploids backcrossed readily to tetraploids and hexaploids, but they crossed only rarely with diploids, 2n=14. Chromosome numbers in 5x‐2x, 5x‐4x, 5x‐5x, and 5x‐6x hybrids ranged from 2n=21 to 25, 2n=28 to 35, 2n=28 to 42, and 2n=35 to 60, respectively. Three hyperoctoploid hybrids—2n=58, 59, and 60—from 5x‐6x crosses probably resulted from union of unreduced male gametes, n=42, and reduced eggs, n=16 to 18. The pentaploids produced functional reduced gametes with n=14 to 21 chromosomes, and the gametic chromosome numbers were distributed somewhat normally, with a mean between n=17 and 18. High multivalent associations at metaphase‐I in some hybrids were caused by a combination of autoploidy and structural heterozygosity. Fully fertile tetraploid and hexaploid hybrids were recovered immediately from 5x‐4x and 5x‐6x crosses, respectively. Grass breeders should not find it difficult to transfer genes, chromosomes, or even whole genomes between tetraploid and hexaploid crested wheatgrasses. Genetic transfer between diploid and polyploid races is somewhat more difficult.