Estresses hídrico e salino como estratégias de biofortificação de morangos

Abstract

As an alternative to complementing existing interventions for improving food safety and nutritional and functional quality, biofortification is a strong strategy. Among the application strategies, the application of abiotic stresses at mild levels may result in the increase of metabolites with antioxidant potential, positively influencing the quality of food, without affecting the productivity of agricultural crops. Not only in large crops (rice, potatoes, beans, bananas, wheat and manioc) but also in minor crops such as onions, lettuce and strawberries. In this study, strawberry plants were submitted to different levels of drought and salt stress, aiming at the identification of mild levels in these conditions, through variables involving biochemical-physiological and molecular aspects. For this, the characterization of reference genes for strawberry fruits was carried out. Subsequently, studies of stress levels were performed, initially identifying the mild level of saline stress (80 mM NaCl). After a study with water stress, although there was an increase in the contents of compounds with antioxidant potential, production and development were affected. In addition, there was a need for the quantification of abscisic acid (ABA) due to possible involvement in these stress conditions. Therefore, the validation for ABA extraction and its derivatives, such as phaseic acid (PA), dihydrophaseic acid (DPA) and ABA-glucose ester (ABA-GE) were performed. Finally, other levels of drought stress were tested, and repeated the level previously found in the study of salt stress, for comparison. Two mild levels of drought stress were found (85% and 95% of crop evapotranspiration). In general, the results of the studies presented the validation of the reference genes for strawberry under conditions of salt and drought stress. A fast, simple and validated method was obtained for extraction and quantification of ABA, ABA-GE, PA and DPA in strawberry. Strawberry fruits with higher levels of compounds with antioxidant potential, without affecting yield, were obtained in both mild stress conditions, being the ABA-dependent responses. It is important to highlight that among the evaluated variables, the compounds of foci in general of the studies carried out were those related to the metabolic pathway of the phenylpropanoids and flavonoids, ascorbic acid and ABA, where both the first mentioned pathways had relation with the ABA pathway. In addition, in this study it was possible to obtain mild levels of salt and drought stress as potential biofortification strategies.