PLANT TOLERANCE TO DROUGHT: MODULATION OF STOMATAL MOVEMENTS

Plants are continuously exposed to several types of abiotic and biotic stresses. As sessile organisms, the mechanisms developed by plants to respond to those stresses are extremely vital for the plant growth and survival. Drought is one of the most common environmental stresses to which plants are exposed and the major cause of losses in crop production throughout the world. One of the primary plant response against water loss and dehydration is reducing the transpiration from the leaves by the closure of stomatal pores, guard cells in fact sense and respond to the environmental changes by the activation of complex intracellular signalling cascades followed by a variation of their turgor pressure and volume. Thus, understanding the complex mechanisms that control the opening and closure of stomata represents an attractive goal. In this PhD thesis the results obtained by the analysis of two Arabidopsis genes involved in stomatal movements, AtMYB60 and γVPE, are presented. The approach performed to characterise putative targets of AtMYB60, a transcription factor specifically expressed in guard cells, was described. Then, the AtMYB60 promoter was characterised through serial deletion and mutagenesis analysis and some DOF-binding sites were identified as fundamental cis-elements for the specific activity of this promoter in guard cells. Finally, the improved tolerance to water stress of γvpe plant was reported and the phenotypic alteration of the mutant in stomatal aperture was described.