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sur le développement des zones arides et semi-arides

Titre : ECO-PHYSIOLOGICAL CHARACTERIZATION OF NEW GRAPEVINE ROOTSTOCKS UNDER DROUGHT STRESS

Auteur : GROSSI Danielle

Université de soutenance : Università degli Studi di Milano

Grade : Tesi di dottorato 2015

Résumé partiel
The objectives of grapevine rootstock breeding selections have undergone a continuous evolution over the years. From the first American vine species introduced to face the invasion of phylloxera and the mildews through Europe, recent breeding programmes aims to obtain plants which are also tolerant to biotic and abiotic stresses such as nematodes, drought and salt stress. Furthermore, the main present interest is on rootstocks that show good performance in different places and in favorable years, but that maintain a good efficiency in difficult conditions. The selection of grapevine rootstocks for resistance to drought conditions is particular important across the activities of modern breeding. Water stress tolerance but above all the water use efficiency (WUE) is becoming more and more important cause the variability of the environmental factors such as limited availability and irregular distribution of water resource. The achievement of the objectives of selection is closely linked to the efficiency and quality of characterization of the phenotype under stress conditions. Traditional phenotyping techniques, although consolidate and widespread, showed considerable limitations like time-consuming and destructive methods. Current technologies allow the development of new systems named high-throughput phenotyping techniques. Thermography, detecting heat patterns in the infrared-wavelength spectrum, is one of the techniques applied in viticulture to assess the plant water conditions. In addition to phenomics techniques, the detection of changes at the molecular level related to the ability to modify the phenotype under stress also play key roles. The analysis of the changes in gene expression induced by water stress is part of this evolution and the analyses of the transcriptional regulation of some genes involved in the responses to water deficiency shown particular interests. The present work aims to characterize the eco-physiological responses of new grapevine rootstocks under water stress in comparisons with the most widespread commercial rootstocks and other genotypes of Vitis spp. In particular the study focuses on the strategies in response to water stress and how these modifications can be transmitted to the scion by the rootstock. The first goal achieved has been the validation of the methods used in high-throughput phenotyping. Thermography has proven a valuable tool in order to assess the water condition of the plant and its evolution during the experiments. The effects of water stress on the variation of stomatal conductance and the rate of growth of the plants have been confirmed allowing the acceleration in phenotyping. It was also possible classify the different behaviors in response to water stress conditions providing a database of phenotypic information to be associated with genotypic data.

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