Using plants of agronomical interest, the general objective of this line is to increase the knowledge of basic intracellular mechanisms that can allow obtaining plants tolerant to different abiotic and biotic stresses, as well as plants with a more efficient carbon assimilation. Another objective is to get more information on the genes and mechanisms that control the reproduction, in order to improve the crop quality and yields. Thus, this research line studies the function of reactive oxygen and nitrogen species (ROS and RNS) in the cell signal transduction and expression of different antioxidative enzymes during plant development and fruit ripening and in response to abiotic and biotic stresses. Likewise, the involvement of processes such as photosynthesis in redox signalling and efficient carbon assimilation as well as in plant tolerance mechanisms to biotic and abiotic stress is also studied. Another research in this line accomplishes an integrated approach to study the mechanisms of ion homeostasis in plants in order to develop biotechnological applications to improve salt tolerance and mineral nutrition efficiency. Finally, the gene products involved in pollen and pistil development, pollen germination, pollen tube growth and pollen-pistil interactions are investigated as well as the signalling mechanisms implicated in pollen tube orientation and guidance in the pistil. The plants studied are basically pea, tomato, pepper, olive, strawberry, and barley, and the approaches used include biochemical, molecular, in vitro and in plant functional analysis, proteomic, crystallographic, immunological and imaging methods. Keywords: abiotic stress; antioxidants; biotic stress; Cd; chloroplasts; crop plants; development; embryogenesis; fructose-1,6-bisphosphatase; functional analysis; Na+, Ca2+, H+ and K+ homeostasis; ion transporters; peroxisomes; pistil; peroxiredoxin; plant pathogen; pollen; ROS; RNS; salinity; signalling