Cytology and Fertility of Advanced Populations of Elymus lanceolatus (Scribn. & Smith) Gould × Elymus caninus (L.) L. Hybrids
Within the wheatgrasses and wildryes, amphiploids are frequently made as a means for introgressing desirable traits and restoring fertility in hybrids between diverse species. This study reports the cytology, fertility, and morphological characteristics of Elymus lanceolatus (Scribn. & Smith) Gould, E. caninus (L.) L., their F1 hybrids, advanced generations (F7 and F8), and three generations of advanced amphiploid progenies (C1, C2, and C3). Meiotic chromosome associations of E. lanceolatus and E. caninus are typical of allotetraploids. Chromosome pairing in the F1 hybrids suggests a close relationship between the two parents. Bivalent associations most frequently observed in the F7 and F8 were 14 bivalents. After multiple generations of harvesting available seed each generation from 10 plants, an increase in meiotic regularity was observed in the advanced F generations. Aneuploidy in the amphiploids (C generation) was observed in the C2 and C3 generations with chromosome numbers ranging from 47 to 56. The C1 generation had significantly fewer univalents per cell than the C2 and C3 generations. Combined across chromosome numbers, there was a significant decrease in the number of bivalents from 22.48 to 21.36 to 20.27 in each succeeding C generation, respectively. After seven generations of seed increase, pollen stainability increased from less than 1% in the F1 hybrid to 87 and 85% in the F7 and F8 generations, respectively. Chromosome doubling significantly reduced pollen stainability in the C1, C2, and C3 generations as compared to the parents and advanced F generations. Cluster analysis was able to separate the parents and the different hybrid populations.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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