Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/30/2005
Publication Date: 1/10/2006
Citation: Santos, A.G., Livingston, D.P., Jellon, R.N., Wooten, D.R., Murphy, J.P. 2006. A cytological marker associated with winter hardiness in oat.. Crop Science 46:203-208. Interpretive Summary: During normal plant reproduction, pieces of chromosomes can become detached and then re-attach to other chromosomes. This is called a translocation. When translocations involve large portions of chromosomes they can be identified using standard cytogenetic techniques with a light microscope. Some oat genotypes have a translocation between chromosome number 17 and chromosome number 7C. We discovered a winter hardy oat cultivar which had the translocation and a non hardy cultivar that did not have the translocation. We hypothesized that genes for freezing tolerance may be located within the pieces of chromosome which had been translocated. To test this hypothesis we crossed the two cultivars and developed a population with and without the translocation. When we freeze-tested the population we found that freezing tolerance was associated with the translocation and have deduced that a group of genes for freezing tolerance are located within the piece of chromosome that is being translocated.
Technical Abstract: The intergenomic translocation T7C-17 occurs at different frequencies in fall- versus spring-sown hexaploid oat germplasm. The objectives of this experiment were to evaluate crown meristem freeze tolerance and winter field survival among 94 random F4-derived lines from the cross between the cultivars Wintok (T7C-17, winterhardy), and Fulghum (non-T7C-17, less winterhardy) and to examine the association between these winterhardiness traits and '7C-17. Crown meristem freeze tolerance was evaluated in a three replicate randomized complete block design in controlled environment growth cabinets. Field survival was evaluated in a three replicate randomized complete block design at Laurel Springs, NC during the 1999-2000 season. Greater crown meristem freeze tolerance and greater winter field survival were associated with the presence of T7C-17. Lines heterozygous for the translocation had similar levels of crown meristem freeze tolerance and field survival as lines homozygous for the translocation. Twenty two percent of the variation in crown meristem freeze tolerance and 27% of the variation in field survival was accounted for by translocation status. The observed frequencies of translocation homozygotes and heterozygotes did not fit the expected frequencies for single factor segregation in the F4 generation. There were almost three fold as many homozygotes with the translocation as homozygotes without the translocation which indicated preferential selection for T7C-17 during inbreeding. Our results suggested that T7C-17 might be isolating, in terms of recombination, either a dominant allele or a group of loci conditioning winterhardiness in our population.