Seasonal patterns of growth, dehydrins and water-soluble carbohydrates in genotypes of Dactylis glomerata varying in summer dormancy |
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Authors: | Volaire F Norton M R Norton G M Lelièvre F |
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Institution: | 1 Institut National de Recherche Agronomique (INRA), LEPSE, 2 place Viala, 34060 Montpellier, France, 2 NSW Department of Primary Industries, PO Box 408, Queanbeyan, NSW 2620, Australia and 3 School of Land and Food Sciences, University of Queensland, St Lucia, Qld 4072, Australia |
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Abstract: | Background and Aims Summer dormancy in perennial grasseshas been studied inadequately, despite its potential to enhanceplant survival and persistence in Mediterranean areas. The aimof the present work was to characterize summer dormancy anddehydration tolerance in two cultivars of Dactylis glomerata(dormant Kasbah, non-dormant Oasis)and their hybrid using physiological indicators associated withthese traits. Methods Dehydration tolerance was assessed in a glasshouseexperiment, while seasonal metabolic changes which produce putativeprotectants for drought, such as carbohydrates and dehydrinsthat might be associated with summer dormancy, were analysedin the field. Key Results The genotypes differed in their ability tosurvive increasing soil water deficit: lethal soil water potential(s) was 3·4 MPa for Kasbah (althoughnon-dormant), 1·3 MPa for Oasis,and 1·6 MPa for their hybrid. In contrast, lethalwater content of apices was similar for all genotypes (approx.0·45 g H2O g d. wt1), and hence the greater survivalof Kasbah can be ascribed to better drought avoidancerather than dehydration tolerance. In autumn-sown plants, Kasbahhad greatest dormancy, the hybrid was intermediate and Oasishad none. The more dormant the genotype, the lower the metabolicactivity during summer, and the earlier the activity declinedin spring. Decreased monosaccharide content was an early indicatorof dormancy induction. Accumulation of dehydrins did not correlatewith stress tolerance, but dehydrin content was a function ofthe water status of the tissues, irrespective of the soil moisture.A protein of approx. 55 kDa occurred in leaf bases of the mostdormant cultivar even in winter. Conclusions Drought avoidance and summer dormancy arecorrelated but can be independently expressed. These traitsare heritable, allowing selection in breeding programmes. |
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Keywords: | Orchard grass drought tolerance avoidance dehydration dehydrins carbohydrates Dactylis glomerata summer dormancy |
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