Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 26, 2004
Publication Date: December 26, 2004
Citation: Jensen, K.B. 2004. Cytology and fertility of advanced populations of elymus lanceolatus (scribn. & smith) gould x elymus caninus (l.) l. hybrids. Crop Science 45:1211-1215. Interpretive Summary: Within the wheatgrasses and wildryes, hybrids are frequently made to combine desirable traits from two different species. This study reports on the chromosome behavior of a hybrid between two species Elymus lanceolatus from the New World and E. caninus from the Old World and advanced generations. Chromosome pairing in the hybrids suggests a close relationship between the two parents from different origins. After multiple generations of harvesting available seed each generation, an increase in chromosome pairing regularity, viable pollen, and seed set was observed in the advanced generations when the chromosome number was 28. However, when the chromosome number was 56, chromosome pairing was less regular and the hybrids had lower viable pollen and reduced seed set. Based on five morphological characters including [plant height (cm), leaf width (mm), leaf length (cm), number of leaves per culm, and number of internodes per culm] the 28 chromosome hybrids could be separated from the 56 chromosome hybrids.
Technical Abstract: Within the wheatgrasses and wildryes, amphiploids are frequently made as a mechanism to introgress desirable traits and restore 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, 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 from the parents and advanced F-generations. Cluster analysis was able to separate the parents and the different hybrid populations.