|Williams, Norman - RETIRED ARS|
Submitted to: Plant Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 11, 2002
Publication Date: June 30, 2003
Citation: KLINDWORTH, D.L., WILLIAMS, N.D. A DEMONSTRATION AND SUGGESTED USES FOR THE MULTIPLOID MUTANT IN INTERSPECIFIC HYBRIDIZATION. PLANT BREEDING. 2003. VOL. 122:213-216. Interpretive Summary: When crossing wild species to durum wheat, four generations of plants are normally required to add a single chromosome from the wild species to durum. We investigated a mutant of durum wheat which has abnormal cell division. Because of this abnormal division, when the mutant is used in crosses to wild species, we can produce one of the intermediate generations more quickly than by conventional techniques. The result is that breeding time is reduced from four generations to three. We tested this process in crosses to rye and three wild wheats. We were able to speed the breeding process in three of the four crosses. We observed that, compared to using a standard durum cultivar, the mutant did not cross as easily to rye. However, this problem was offset by the fact that we could visually select seeds that had the desired chromosome complement by selecting plump seeds in crosses to rye and thin seeds in crosses to one of the wild wheats. We also determined that 50.5 florets must be pollinated to recover one of the desired seeds in the crosses to rye but only 15.1 florets needed to be pollinated to recover a desired seed in the cross to the wild wheat. This translates to one desirable seed for every 2-3 heads of the mutant pollinated with rye and one desirable seed for every head pollinated with wild wheat.
Technical Abstract: Genotypes that form unreduced gametes, such as the multiploid mutant of durum wheat (Triticum turgidum L.), may accelerate wide hybridization by enabling manipulation of the genomic content of the egg mother cell. Our objective was to study the mutant's crossability to diploid alien species, and to test the frequency of recovery and viability of pentaploid hybrids. The diploid species were rye (Secale cereale L.), Triticum monococcum L., Triticum tauschii (Coss.) Schmal., and Triticum speltoides (Tausch) Gren. ex Richter. The mutant/rye cross had a two-thirds reduction in percent seed set when compared to T. turgidum L. cv Langdon/rye crosses. This reduced crossability did not hinder recovery of pentaploid hybrids due to an association of pentaploid hybrids with plump; viable seeds of the mutant/rye cross, and with shriveled seeds of the mutant/T. monococcum cross. Mature, plump seeds from the mutant/rye cross were germinated and pentaploid hybrids were recovered. Altering the endosperm balance number ratio explains the association of pentaploids with differing endosperm types in the rye and T. monococcum crosses. The frequency of pentaploid hybrids was one for 50.5 florets pollinated with rye, and one for 15.1 florets pollinated with T. monococcum. Fertilization of unreduced gametes in the multiploid mutant will facilitate interspecific hybridization by reducing the time to produce pentaploid plants.