Genome‐wide association analysis of freezing tolerance in soft red winter wheat

Abstract

Freezing tolerance is likely to be an important adaptation for both natural populations and crop cultivars like winter wheat (Triticum aestivum L.). In the United States, winter wheat represents 80% of the total wheat production. Understanding the genetic basis of freezing tolerance in wheat furthers our knowledge of abiotic stress tolerance in plants and may inform breeding programs aimed at adjusting the level of freezing tolerance for a given region. We examined freezing tolerance in a 267-line panel of elite soft red winter wheat that has previously been used for genome-wide association study (GWAS) on agronomically important traits. We were specifically interested in determining the extent of genetic variation for freezing tolerance within the panel, what the genetic basis of that variation is, and if there are correlations between freezing tolerance and other agronomically important traits. We found significant variation in freezing tolerance among the lines, measured as survival through three total days at −8 ˚C. We performed a GWAS on freezing tolerance and identified 13 candidate loci, with nearby candidate genes involved in different functions potentially associated with freezing tolerance. In addition, we found significant correlations between freezing tolerance and seven previously published yield related traits. In summary, we found considerable variation in freezing tolerance in this panel that is associated with yield related traits. Thus, these lines may be useful for breeding programs seeking to optimize freezing tolerance for present and future climatic conditions. INTRODUCTIONWheat (Triticum aestivum L.) is one of the most important crops worldwide. It is cultivated in ∼200 million ha (http: //www.fao.org/faostat/en/#data/QC/visualize) (Zhao et al., 2013) and provided about 20% of all dietary calories consumed globally (