Meiotic Stability of Intersubspecific Hybrids of Snake River × Thickspike Wheatgrasses
- Thomas A. Jones ,
- Richard R-C. Wang and
- Li-Hui Li
Based on genomic makeup and partial hybrid fertility, Snake River wheatgrass (proposed name Elymus lanceolatus ssp. wawawaiensis) has been recognized since 1986 as a subspecies of E. lanceolatus (Scribn. & J.G. Smith) Gould. Thus it is conspecific with thickspike wheatgrass [E. lanceolatus ssp. lanceolatus (Scribn. & J.G. Smith) Gould]. However, these two wheatgrasses display distinct morphological features, physiological traits, geographical distributions, and habitat preferences. Hybridization of the two subspecies generates valuable germplasm with considerable heterosis, but the hybrids are partially male sterile. Our objective was to determine the degree and nature of hybrid male sterility. Mean chromosome pairing (and pollen stainability) was 0.11 I + 13.90 II + 0.02 IV (84%) for ‘Secar’ Snake River wheatgrass and 0.10 I + 13.83 II + 0.01 III + 0.05 IV (78%) for ‘Bannock’ thickspike wheatgrass, the parents in the original cross, 0.60 I + 13.61 II + 0.01 III + 0.04 IV (55%) for three F1 hybrid populations, and 0.09 1 + 13.92 II + 0.01 III + 0.03 IV (80%) and 0.441 + 13.66 II + 0.01 Ill + 0.05 IV (64%) for backcross populations to Bannock thickspike wheatgrass and BBR-syn Snake River wheatgrass, respectively. The low frequency of multivalents in the hybrids indicated that male sterility resulted from some degree of genetic incompatibility rather than a major chromosomal rearrangement. Because hybrid and backcross populations possessed reasonable levels of pollen stainability and chromosome abnormalities were absent, they should respond readily to selection for high pollen stainability.
Copyright © 1995.