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Oregon State University (2001)

Association between dehydrin proteins and drought stress tolerance in seven wheat cultivars adapted to the Pacific Northwest of the USA

Lopez, Cesar

Titre : Association between dehydrin proteins and drought stress tolerance in seven wheat cultivars adapted to the Pacific Northwest of the USA

Auteur : Lopez, Cesar

Université de soutenance : Oregon State University

Grade : Doctor of Philosophy (Ph. D.) in Crop Science 2001

Résumé
The Pacific Northwest (PNW) is an important region for winter wheat production in the USA, where water deficits are often present at sowing and during grain filling. Consequently, improving the genetic adaptation of wheat cultivars to drought stress represents one of the main objectives in breeding programs. An observed biochemical response to dehydrative stress is the accumulation of a family of proteins called dehydrins, which are believed to protect membranes and macromolecules against denaturation. Seven cultivars, ’Connie’, ’Gene’, ’TAM105’, ’Rod’, ’Hiller’, ’Rhode’, and ’Stephens’, were evaluated in four experiments under progressive drought stress to characterize the accumulation of dehydrin proteins and their association to stress tolerance at adult plant (during grain filling) and seedling stages. In the adult plant experiments, a 24 kDa dehydrin was present in all leaves sampling dates and cultivars studied. Differences in the accumulation of this dehydrin protein were observed between cultivars in the third sampling date (four days of stress). This differential accumulation was associated to stress tolerance characterized by a lower reduction in yield and in the rate of decrease in leaf water potential in Connie, TAM105, Gene and Stephens. In contrast to leaves, an increasing number of dehydrin bands 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. A 24 kDa dehydrin was also observed in the seedling experiments on sampling dates fourth, fifth and sixth, when cultivars were subjected to stress. No dehydrins were present in the non-stress treatment. Connie, TAM105, and Gene started to accumulate dehydrins at the fourth sampling date, while other cultivars showed dehydrins only in the sixth sampling date. The presence of dehydrin proteins observed in leaves of seedlings was related to drought stress tolerance characterized by a lower reduction in the shoot dry matter production in the most tolerant cultivars Connie, TAM105, and Gene. Although the specific role of these proteins remains unknown, their association with stress tolerance suggests that dehydrins might be used to improve the adaptation to drought

Mots clés : Winter wheat — Effect of drought on — Northwest, Pacific — Wheat — Effect of stress on — Genetic aspects

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