Mapping Genetic Factors Associated with Winter Hardiness, Fall Growth, and Freezing Injury in Autotetraploid Alfalfa

Abstract

trolling these traits interact with each other and variable environmental stresses to determine winter hardiness. Winter hardiness is a complex trait and one of the most importantThe severe winters necessary to evaluate winter hardiadaptations for alfalfa (Medicago sativa L.) grown in northern cliness only occur every 3 to 4 yr, on average, in the upper mates. In the absence of winter hardiness data, alfalfa breeders predict the potential of genotypes with component traits related to winter Midwest (Shaeffer et al., 1992) further complicating hardiness. This research was undertaken to identify and compare breeding for winter hardiness. some of the genomic regions that control winter injury (WI) and twoIn the absence of direct measurements of winter harcomponent traits, fall growth (FG) and freezing injury (FI). Two diness, the winter hardiness potential of genotypes and plants, B17 and P13, representing the extremes for each trait were cultivars has been predicted from related traits that are crossed, and a F1 plant was backcrossed to each parent to create two believed to represent components of winter hardiness. populations of 101 individuals each. Each population was scored forFall dormancy has traditionally been the primary com-82 single dose restriction fragment loci, and 17 or 19 two-allele loci ponent used to predict winter hardiness in alfalfa. Short and evaluated for FG, FI, and WI in 2 yr of replicated field trials. days and cool temperatures trigger the fall dormancy Trait measures over the 2 yr were significantly correlated (r ϭ 0.71, response (Nittler and Gibbs, 1959), which can be scored r ϭ 0.42, and r ϭ 0.76 for FG, FI, and WI, respectively). Significant easily by measuring vertical regrowth following the last correlations also existed between WI and FG (r ϭ 0.50 and 0.56) and FI (r ϭ 0.34 and 0.58) for each year. One to six single dose restriction

A Unified Framework for Mapping Quantitative Trait Loci in Bivalent Tetraploids Using Single-dose Restriction Fragments: A Case Study from Alfalfa

“…Each backcross obtains 101 progenies used for mapping. Two hardiness traits, freezing injury measured by electrical conductivity and winter injury, were measured in two successive years (Brouwer et al 2000). Because the two original parents are not pure inbred lines, the two-way backcrosses virtually present a full-sib family in which many different marker types may be segregating (Wu et al 2002).…”

Applied Genetics and Genomics in Alfalfa Breeding

“…Major QTL related to yield and morphological traits [37,38], fall dormancy and winter-hardiness [69,70], persistence [71], viability [53], self-fertility [72], resistance to Stagonospora melioti [68], resistance to C. trifolii [73], aluminum tolerance [57,74] and water use efficiency [75] have been mapped in alfalfa, primarily in tetraploid populations (Table 1). Several factors potentially limit the precision and power of mapping in tetraploid alfalfa.…”

Establishment and Early Yield Development of Five Possible Alternatives to Trifolium repens as a Grassland Legume

“…A good establishment (Finch-Savage, 1995) of legumes associated with sufficient winter tolerance (Brouwer, Duke, & Osborn, 2000) is the basis for a good yield and sufficient yield contribution in a mixture in the first main production year. In our experiments, T. repens and M. lupulina but also L. corniculatus showed a good www.ccsenet.org/jas Journal of Agricultural Science Vol.…”