Abstract
The remarkable phytogeographic characteristics of the Brazilian savanna (Cerrado) resulted in a vegetation domain composed of plants with high structural and functional diversity to tolerate climate extremes. Here we used a key Cerrado species (Dipteryx alata) to evaluate if species of this domain present a mechanism of stress memory, responding more quickly and efficiently when exposed to recurrent drought episodes. The exposure of D. alata seedlings to drought resulted in several changes, mainly in physiological and biochemical traits, and these changes differed substantially when the water deficit was imposed as an isolated event or when the plants were subjected to drought cycles, suggesting the existence of a drought memory mechanism. Plants submitted to recurrent drought events were able to maintain essential processes for plant survival when compared to those submitted to drought for the first time. This differential acclimation to drought was the result of orchestrated changes in several metabolic pathways, involving differential carbon allocation for defense responses and the reprogramming and coordination of primary, secondary and antioxidant metabolism. The stress memory in D. alata is probably linked the evolutionary history of the species and reflects the environment in which it evolved.
Highlights
The remarkable phytogeographic characteristics of the Brazilian savanna (Cerrado) resulted in a vegetation domain composed of plants with high structural and functional diversity to tolerate climate extremes
All results presented and in the following ones were collected on the last day of application of the treatments, that is, after six days of exposure of the plants to one or three cycles of drought
Differential acclimation represents a crucial factor to be considered in order to better understand the ecology and evolutionary history of plant species, with potential implications in conservation programs
Summary
The remarkable phytogeographic characteristics of the Brazilian savanna (Cerrado) resulted in a vegetation domain composed of plants with high structural and functional diversity to tolerate climate extremes. Studies of the Brazilian phytogeography demonstrated that the Cerrado may have been a transition zone in which species were exposed to fluctuating environmental conditions for thousands of years[4], resulting in the emergence of the high structural and functional diversity in morpho-anatomical and physiological traits which allows species of this domain to tolerate contrasting climatic extremes. An example of such fluctuation in environmental conditions, commonly observed in Cerrado, is its well-defined seasons, characterized by a long period of water restriction (approximately five months), followed by a rainy period[5]. Studies with plants subjected to repeated stressful events demonstrate the existence of a differential plant acclimation mechanism, called “stress memory”[18]
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