Selection of new grape rootstocks resistant to abiotic stresses through the development and validation of physiological and molecular markers
Progetto Phylloxera, an insect detrimental for the roots of Vitis vinifera, has been the main input to force viticulture to employ specific rootstocks. The grape rootstocks that are currently employed are generally hybrids of American species of the genus Vitis, constituted mainly between the end of the 19th century and the first decades of the 20th century. Due to the narrow genetic background and phenotypic selection based only on few traits (rooting ability, phylloxera resistance, scion-induced vigour and, in a few cases, tollerance to iron chlorosis). Italian rootstocks to date available show scarce resistance to environmental as well as soil (salt, drought, and limestone) stresses. Also in light of the dramatic climate-change events occurring in the last recent years, the selection of resistant rootstocks is a crucial factor for the development of sustainable agricultural models (moderate irrigation and fertilization and recovery of marginal soils) ~and for assuring optimal maturation profiles of grapes.
The selection of genotypes able to cope with stress conditions requires a thorough knowledge of the molecular, biochemical and physiological bases of stress resistance. The complexity of the features of interest and the interactions occurring among physical factors (e.g. seasonal variations) and the dynamic plant behaviour lead the research to rely only on multiple integrated approaches able to provide a wider range of information suitable for the interpretation of complex physiological processes. Aim of the present project will be the study of the responses of newly established rootstocks to abiotic stresses in both controlled and open field conditions, taking into account different soilclimatic environments and different rootstock-scion combinations. Genotypes previously selected for resistance to drought, salinity and calcareous soils will be characterized, in controlled and open field conditions, at the genetic and physiological levels. At the genetic level, a draft of their sequence will be obtained through the SOLiD DNA sequencer; at the physiologic level, genotypes will be characterized on the basis of the resistance by the evaluation, during the progression of stress, of stomatal/non-stomatal limitations of photosynthesis, possible variations in water conductance at the mesophyll, changes in maximum carboxylation capacity and ability to maintain an adequate water cellular balance. Once undoubtedly characterized, the plant material will undergo several kinds of analyses. In order to identify genes and proteins involved in the resistance to abiotic stresses and therefore useful as biomarkers, susceptibile and resistant rootstocks will be compared by the use of high-throughput transcriptomic and proteomic approaches. In addition, expression data will be accompanied by metabolomic analyses. These analyses, supported by a profitable multivariate statistical integration, will hopefully yield new insights on the processes involved in the plant responses to stress conditions and help in understanding the involvement of biochemical traits. Insights emerging from these activities will be further analyzed (e.g., by Western blotting and measurement of enzyme activities, etc.) in order to verify their reliability and gain a deeper insight on the biochemical framework. Many efforts will be devoted to the study of rootstock/scion communication, that implies the pioneering analysis aimed to the definition of the possible changes in chemical composition (phytoregulators, peptides and small RNAs) of the xylem sap during stress syndromes. Another critical point that will be considered in the present Project because of its relevance in limestone soils is Fe-deficiency. The proposed research will consider the Fe uptake mechanisms and the physiological and biochemical modifications which are elicited by plants in response to Fedeficiency in calcareous soil. The pa
The selection of genotypes able to cope with stress conditions requires a thorough knowledge of the molecular, biochemical and physiological bases of stress resistance. The complexity of the features of interest and the interactions occurring among physical factors (e.g. seasonal variations) and the dynamic plant behaviour lead the research to rely only on multiple integrated approaches able to provide a wider range of information suitable for the interpretation of complex physiological processes. Aim of the present project will be the study of the responses of newly established rootstocks to abiotic stresses in both controlled and open field conditions, taking into account different soilclimatic environments and different rootstock-scion combinations. Genotypes previously selected for resistance to drought, salinity and calcareous soils will be characterized, in controlled and open field conditions, at the genetic and physiological levels. At the genetic level, a draft of their sequence will be obtained through the SOLiD DNA sequencer; at the physiologic level, genotypes will be characterized on the basis of the resistance by the evaluation, during the progression of stress, of stomatal/non-stomatal limitations of photosynthesis, possible variations in water conductance at the mesophyll, changes in maximum carboxylation capacity and ability to maintain an adequate water cellular balance. Once undoubtedly characterized, the plant material will undergo several kinds of analyses. In order to identify genes and proteins involved in the resistance to abiotic stresses and therefore useful as biomarkers, susceptibile and resistant rootstocks will be compared by the use of high-throughput transcriptomic and proteomic approaches. In addition, expression data will be accompanied by metabolomic analyses. These analyses, supported by a profitable multivariate statistical integration, will hopefully yield new insights on the processes involved in the plant responses to stress conditions and help in understanding the involvement of biochemical traits. Insights emerging from these activities will be further analyzed (e.g., by Western blotting and measurement of enzyme activities, etc.) in order to verify their reliability and gain a deeper insight on the biochemical framework. Many efforts will be devoted to the study of rootstock/scion communication, that implies the pioneering analysis aimed to the definition of the possible changes in chemical composition (phytoregulators, peptides and small RNAs) of the xylem sap during stress syndromes. Another critical point that will be considered in the present Project because of its relevance in limestone soils is Fe-deficiency. The proposed research will consider the Fe uptake mechanisms and the physiological and biochemical modifications which are elicited by plants in response to Fedeficiency in calcareous soil. The pa