Genetic Control of Cold Hardiness and Vernalization Requirement in Winter Wheat

Abstract

A high level of cold hardiness is essential to ensure consistent overwintering of wheat (Triticum aestlvum L.) in the Northern Great Plains region of North America. Consequently, a clear understanding of the genetic control of cold hardiness would facilitate plant breeding efforts directed at cultivar improvement for this area. Although several genetic studies have been conducted, there is not a general consensus on the mode of gene action controlling the expression of cold hardiness in wheat. This study used one spring and four winter cultivars representing a wide range of cold hardiness potential to investigate the mode of inheritance and interaction of cold hardiness, determined in a controlled environment that allowed for maximum expression of cold hardiness potential, and vernalization requirement in wheat. Differences in growth habit between parental cultivars were controlled by the Vrn~ gene. Cold hardiness, estimated as the temperature at which 50% of the plant population was killed (LT5o), was controlled by genes with either dominant or additive effects. At least one dominant gene was associated with cold hardiness differences between spring and winter wheat, while genes with mainly additive effects determined differences in cold hardiness among cultivars with the winter growth habit. Broad sense heritability estimates for LT5o in the controlled environment considered ranged from 0 to 88% with most estimates exceeding 50%. In the F2-derived F 3 generation, hardy transgressive segregates were most common in crosses between relatively nonhardy cultivars, but no segregates were significantly hardier than the hardiest parental cultivar. Lack of a vernalization requirement did not hinder the development of cold hardiness; however, distribution of F2-derived F 3 lines provided evidence of possible genetic linkage or pleiotropism between the gene segregating for growth habit and a gene or genes controlling cold hardiness. C OLD HARDINESS iS a complex quantitative trait conditioned by the plant genotype and the environment in which the plant is grown (Rohde and Pulham, 1960). Although several genetic studies have

Dehydrins: genes, proteins, and associations with phenotypic traits

“…3; Bezant et al, 1996). The Vrnl gene might be pleiotropic, affecting both the growth habit and low temperature tolerance in wheat (Brule-Babel & Fowler, 1988) making it difficult to separate clearly Vrnl from the Frl gene for frost tolerance. However, Galiba ci al (1995) found that Vrnl and Frl are indeed separate genetic determinants on wheat 5A.…”

Cold hardiness of wheat near-isogenic lines differing in vernalization alleles

“…Segregating progeny of crosses from winter wheat parents of differing cold hardiness typically exhibit a continuous range of hardiness between the parental extremes, and the freezing tolerance of hybrids typically is near the midpoint of the parents, indicating additive effects (Brule-Babel and Fowler 1988;Limin and Fowler 1993;Sutka 1994). Dominant and additive genetic effects have been found in crosses between spring and winter wheats (Sutka 1981(Sutka , 1984Brule-Babel and Fowler 1988;Limin and Fowler 1993;Askel 1994). The heritability of cold hardiness is estimated to be 63% to 70% (Limin and Fowler 1993).…”

Regulation of Freezing Tolerance and Flowering in Temperate Cereals: The VRN-1 Connection

“…The first major locus affecting freezing tolerance and winter hardiness on homeologous group 5 was designated FROST RESISTANCE-1 (FR-1; Sutka and Snape, 1989). However, since FR-1 cosegregates with VRN-1 in most genetic studies, it is still not clear if FR-1 is an independent gene or just a pleiotropic effect of VRN-1 (Brule-Babel and Fowler, 1988;Sutka and Snape, 1989;Roberts, 1990;Hayes et al, 1993;Francia et al, 2004;Galiba et al, 2009).…”