Submitted to: Heredity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/1998
Publication Date: N/A
Interpretive Summary: Wild grass species have traits that could be used to improve cereal crop species, such as disease resistance and environmental adaptation. To transfer these traits into crops, chromosomes must pair and exchange genes. But wild grass chromosomes often do not pair with cereal crop chromosomes. Tissue culture, growing plant cells on nutrient agar in petri dishes, can change chromosome pairing. Canada wild rye has genes for barley yellow dwarf virus resistance, winter hardiness, and drought resistance. Hybrids between Canada wild rye and barley were put through tissue culture to see if chromosome pairing could be increased. Pairing in the plants derived from tissue culture was higher than in the original hybrids. Other chromosome changes were found. These results show that tissue culture has increased the chance of transferring desired traits from Canada wild rye into barley.
Technical Abstract: Canada wild rye (CWR; Elymus canadensis L.) expresses traits such as barley yellow dwarf virus resistance, winter hardiness, and drought resistance. Hybrids between CWR and barley (Hordeum vulgare L.) are sterile, precluding transfer of these traits into barley. Callus cultures were initiated from these hybrids to promote chromosome recombination and restore fertility. The objectives of this study were to (i) compare meiotic configurations of 17 of these intergeneric hybrids and 117 regenerants, (ii) compare chromosome pairing in regenerants with different cytoplasm, and (iii) examine meiosis in a BC1 plant. Meiotic abnormalities were common. Chromosome pairing in the hybrids was limited. The 2n=21 euploid regenerants had greater pairing and fewer micronuclei on average than the hybrids. Most aneuploid regenerants had fewer paired chromosomes than the euploid regenerants. Regenerants with partially or completely doubled chromosome complements (2n=36-42) showed chromosome instability. Hybrids and regenerants with CWR cytoplasm had more micronuclei than those with barley cytoplasm. The amount of chromosome pairing was not related to the micronuclei frequency. Barley pollination of a stably doubled (2n=42) regenerant resulted in a single BC1 plant that developed spikes. This plant had 28 mitotic chromosomes and showed meiotic chromosome number instability. Backcrosses to this plant produced small embryos for rescue, indicating it is partially female fertile. Attempts to recover BC2 plants are in progress. Results indicate that tissue culture increased chromosome pairing, providing additional opportunity for genetic recombination between the two species.