Wheat dehydrin accumulation in response to drought stress during anthesis

The winter wheat (Triticum aestivum L.) producing region of the US Pacific Northwest (PNW) is often subject to water deficits at sowing and during grain filling. Improved genetic adaptation of wheat cultivars to drought stress is one objective of breeding efforts in the region. Consequently, there is interest in identifying molecular markers associated with drought tolerance. Dehydrins, a family of proteins that accumulate in response to dehydrative stress, may provide a suitable marker for use in breeding programs. Seven cultivars (Connie, Gene, TAM105, Rod, Hiller, Rhode and Stephens) were evaluated in two experiments in which dehydrin accumulation and their association to stress tolerance during grain filling were characterized during progressive drought stress. A24-kDa dehydrin was present in leaves at each sampling date in all seven cultivars. Quantitative differences in accumulation of this protein were observed between cultivars on the third sampling date (4 d of stress). This differential accumulation was associated with stress tolerance characterized by a lower yield reduction and a lowered rate of decrease in leaf water potential in Connie, TAM105 and Gene. In contrast to leaves, an increased number of dehydrins were observed in grains under stress and non-stress treatments. Despite the number of dehydrins detected, there was no apparent association between drought stress and dehydrin expression in grains. Although the specific role of these proteins remains unknown, their association with stress tolerance suggests that dehydrins have utility in improving adaptation to drought and as markers for drought tolerance.