Water suppression indicates the prevalence of the secondary defense system in Piper aduncum

Abstract

The aim of this work was to evaluate the response of Piper aduncum to water suppression. The experiment was conducted in a greenhouse, in an entirely randomized blocks, with five treatments: 0, 2, 4, 6, and 8 days without irrigation. After this period, dry matter, photosynthetic pigments (chlorophyll a, b, and carotenoids), leaf temperature, activity of the enzymes ascorbate peroxidase (APX), catalase (CAT) and superoxide dismutase (SOD) were evaluated. The essential oil content of leaves and roots was also quantified through hydrodistillation, as well as the identification of constituents by CG-MS. The period of water suppression influenced the content of chlorophyll a, carotenoids, and enzymatic activity of APX and CAT. The activities of APX and CAT were reduced under low water availability (CAT only increased after 4 days of suppression). Meanwhile, SOD had its activity increased under eight days of water suppression. In addition, there was an increase in essential oil content when subjected to stress. The predominant classes of constituents in the leaves were sesquiterpenes (32.56-36.54%) and phenylpropanoids (33.12- 44.97%) in the roots. E-nerolidol was the major constituent of leaves (23.56- 26.75%) and apiol (17.57-32.78%) of the roots. Thus, water suppression favors the secondary metabolism of the species.