Cold hardiness expression in interspecific hybrids and amphiploids of the Triticeae

Abstract

Gene expression for cold hardiness was investigated in a number of interspecific or intergeneric hybrids and amphiploids of wheat (Triticum aestivum L. em. Thell. or T. turgidum L.) and other members of the tribe Triticeae to assess the potential of alien species as donors of cold-hardiness genes for the improvement of wheat. Thinopyrum ponticum (Agropyron elongatum) hybrids with nonhardy T. aestivum had cold-hardiness levels similar to that of the more hardy Thinopyrum parent. Hybrids of Triticum cylindricum and both hardy and nonhardy T. aestivum were intermediate in cold hardiness with a tendency toward greater hardiness than the parental mean. Cold hardiness of hybrids between T. aestivum and Thinopyrum intermedium (Agropyron intermedium) was also close to the parental midpoint. Cold hardiness of T. aestivum – Secale cereale hybrids was greater than the less hardy parent. In contrast, cold-hardiness genes were not expressed beyond the level of the wheat parent in amphiploids combining wheat and the very hardy diploid species Agropyron cristatum and Secale cereale. The cold-hardiness level was also poor in an amphiploid produced from two relatively hardy tetraploid species (T. turgidum and T. cylindricum). These observations indicate that changes in ploidy level, relative to the parents, may influence the cold-hardiness potential of an interspecific combination by affecting gene dosage and possibly cell size. Poor expression of cold-hardiness genes from very hardy diploid genomes also indicated some degree of suppression, or homoeoallelic dominance of wheat cold-hardiness genes in amphiploids. Therefore, the performance of an interspecific hybrid or amphiploid of wheat may not give an accurate indication of the potential of alien species as gene donors for the improvement of wheat cold hardiness.Key words: gene expression, Triticum sp., triticale, Thinopyrum sp., Agropyron sp., Secale cereale.