Water deficit modifies the carbon isotopic composition of lipids, soluble sugars and leaves of Copaifera langsdorffii Desf. (Fabaceae)

Abstract

Water defi cit is most frequent in forest physiognomies subjected to climate change. As a consequence, several tree species alter tissue water potential, gas exchange and production of carbon compounds to overcome damage caused by water defi ciency. Th e working hypothesis, that a reduction in gas exchange by plants experiencing water defi cit will aff ect the composition of carbon compounds in soluble sugars, lipids and vegetative structures, was tested on Copaifera langsdorffi i. Stomatal conductance, leaf water potential, and CO 2 assimilation rate declined after a period of water defi cit. After rehydration, leaf water potential and leaf gas exchange did not recover completely. Water defi cit resulted in 13 C enrichment in leaves, soluble sugars and root lipids. Furthermore, the amount of soluble sugars and root lipids decreased after water defi cit. In rehydration, the carbon isotopic composition and amount of root lipids returned to levels similar to the control. Under water defi cit, 13 C-enriched in root lipids assists in the adjustment of cellular membrane turgidity and avoids damage to the process of water absorption by roots. Th ese physiological adjustments permit a better understanding of the responses of Copaifera langsdorffi to water defi cit.