Allelic variations at Dhn4 and Dhn7 are associated with frost tolerance in barley

Abstract

The sequences of the closely linked barley dehydrin genes Dhn4 and Dhn7 are both known to vary allelically. Here we associated allelic constitution at Dhn4/7 with frost sensitivity across a panel of 30 diverse barley varieties. The combined presence of a 6 bp insertion in exon1 of Dhn4 and a 30 bp deletion in exon1 of Dhn7 was restricted to six-rowed winter and intermediate varieties characterised by relatively higher frost tolerance (12 genotypes; LT₅₀ from –14.2°C to –15.6°C). The alternative combination was present with one exception (sixrowed winter variety Alissa) only in spring and two-rowed winter varieties (17 genotypes; LT₅₀ from –10.0°C to –14.3°C). The genetic linkage between Dhn4 and Dhn7 identified e.g. in Dictoo and Morex varieties was verified by segregation analysis of F₂ plants from a cross between two genotypes carrying different allelic combination of Dhn4 and Dhn7 genes (two-rowed spring variety Akcent × six-rowed winter variety Okal). The potential of the former allelic combination as a marker for enhanced frost tolerance was tested in a sample of F₅ derivatives of a cross between the two-rowed winter type variety Monaco (Akcent allele combination) and the six-rowed winter type variety Okal. Plants with the Okal allele combination showed significantly higher frost tolerance than those with the alternative growth habit. The effect of ear type on frost tolerance was insignificant.