Effects of an Intercultivaral Chromosome Substitution on Winterhardiness and Vernalization in Wheat

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During a study on the genetic control of winterhardiness in winter wheat (Triticum aestivum L. group aestivum), a gene that affected vernalization was found on chromosome 3B in the winter wheat cultivar `Wichita.' When chromosome 3B from Wichita was substituted into the winter wheat cultivar `Cheyenne,' the resultant substitution line exhibited a spring growth habit. This is unusual since a cross between the cultivars Wichita and Cheyenne results in progeny that exhibit the winter growth habit. The F(2) plants from a cross of the 3B substitution line to Cheyenne, the recipient parent, segregated 3:1 for heading/no heading response in the absence of vernalization (χ(2) = 2.44). Earliness of heading appeared to be due to an additive effect of the 3B gene as shown by the segregation ratio 1:2:1 (early heading-later heading-no heading) (χ(2) = 2.74). This vernalization gene differs from previously described vernalization genes because, while dominant in a Cheyenne background, its expression is suppressed in Wichita. The gene may have an effect on winter hardiness in Wichita. In a field test for winter survival the 3B substitution line had only 5% survival, while Wichita and Cheyenne had 50 and 80% survival, respectively. No other substitution line significantly reduced winter survival. The difference between Wichita and Cheyenne in winterhardiness may be due to the vernalization gene carried on the 3B chromosome.

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