CONTRIBUIÇÃO DE COMPONENTES MORFOANATÔMICOS, HIDRÁULICOS, BIOQUÍMICOS E HORMONAIS NA ACLIMATAÇÃO A MÚLTIPLOS FATORES DE ESTRESSE EM PLANTAS DE Dipteryx alata

Abstract

The Cerrado is one of the main biomes in Brazil, both in territorial extension and species diversity. According to climate models, abiotic conditions in several regions of Brazil will change dramatically in the near future, especially in relation to rainfall in regions where the Cerrado biome occurs. In order to evaluate the impact of these changes on a native Cerrado plant, baru plants (Dipteryx alata) were subjected to several stressful abiotic factors: water deficit, salinity, and hypoxia. Plants were more vulnerable to salinity and hypoxia than to drought, indicating plant tolerance to water deficit, which is probably related to their evolutionary history. In order to deepen the knowledge of D. alata drought tolerance, the role of ethylene (ETH) was evaluated. For this, a second experiment was set up, in which the plants were subjected only to water deficit, and half of the plants were sprayed with an ETH action inhibitor. Plants sprayed with the ETH inhibitor showed higher stomatal conductance, which allowed the maintenance of a higher photosynthetic rate, but at the same time resulted in decreases in water potential. Plants subjected to water deficit alone, in turn, maintained water potential but showed decreases in photosynthesis, photorespiration and increased hydrogen peroxide concentration. It is noteworthy that although drought-exposed plants in combination with the ETH inhibitor showed higher photosynthesis, it is likely that this will not be sustained in longer droughts since keeping the stomata open would probably result in excessive tissue desiccation. To test this hypothesis, a third experiment was set up. For this, D. alata seedlings were irrigated to field capacity, and half of them received ethylene action inhibitor solution. Then the physiology of these plants was continuously evaluated as the soil dried over the days until plant death. As expected, plants subjected to drought in combination with the ETH inhibitor kept their stomata open for a longer period of time, resulting in cell damage and early death due to hydraulic failure and carbon deprivation.