title: Characterization of freezing tolerance and vernalization in Vern-, a spring-type Brassica napus line derived from a winter cross.
abstract: Exposure of winter brassicas to periods of low temperature decreases the transition required from vegetative to reproductive growth. This low-temperature exposure also results in the acquisition of freezing tolerance. To investigate the relationship between vernalization and freezing tolerance, homozygous microspore-derived (DH) lines were developed from reciprocal crosses between two winter cultivars of Brassica napus L., cv. Cascade and cv. Rebel. A resulting line, termed Vern-, expressed a high degree of freezing tolerance and was selected for study. Analysis of growth and development revealed that Vern- is a true spring type, having completely lost the vernalization requirement. Using markers previously mapped in B. rapa, it was concluded that Vern- inherited freezing-tolerance alleles from Cascade. With regard to vernalization and flowering time, Rebel, although traditionally classified as a winter type, carries spring alleles at the major and some of the minor loci. Vern- inherited these alleles from Rebel, in addition to one spring allele from Cascade. Thus, spring alleles from both parents were critical in establishing the spring phenotype observed in Vern-.
authors.affiliation: Department of Agriculture Food and Nutritional Science, 4-10, Ag/For Center, University of Alberta, Edmonton, Alberta, T6G 2P5, Canada. glen.hawkins@ualberta.ca
authors.forename: Glen P
authors.initials: GP
authors.lastname: Hawkins
authors.forename: Zhanao
authors.initials: Z
authors.lastname: Deng
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Kubik
authors.forename: Anne M
authors.initials: AM
authors.lastname: Johnson-Flanagan
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics / Q000502:physiology*; D000483:Alleles; D029688:Brassica napus / Q000235:genetics / Q000254:growth & development*; D003433:Crosses, Genetic; D005615:Freezing; D005819:Genetic Markers; D010641:Phenotype; D012621:Seasons
chemical_list: D005819:Genetic Markers