Short communication Melia azedarach plants show tolerance properties to water shortage treatment: An ecophysiological study Maria Celeste Dias a , Carla Azevedo a , Maria Costa a, b , Glória Pinto a , Conceição Santos a, * a Laboratory of Biotechnology and Cytometry, Department of Biology/CESAM, University Aveiro, Aveiro, Portugal b Ministério da Educação, Dili, Timor-Leste article info Article history: Received 15 October 2013 Accepted 20 December 2013 Available online 27 December 2013 Keywords: Melia azedarach Water deficit Oxidative stress Photosynthesis ROS Antioxidant system abstract Candidate species for reforestation of areas prone to drought must combine water stress (WS) tolerance and economic or medicinal interest. Melia azedarach produces high quality timber and has insecticidal and medicinal properties. However, the impact of WS on M. azedarach has not yet been studied. Two- month old M. azedarach plants were exposed to WS during 20 days. After this period, plant’s growth, water potential, photosynthetic performance and antioxidant capacity were evaluated. WS did not affect plants’ growth, but induced stomatal closure, reduced net CO 2 assimilation rate (A) and the intercellular CO 2 availability in mesophyll (C i ). WS also reduced the photosynthetic efficiency of PSII but not the pigment levels. WS up-regulated the antioxidant enzymes and stimulated the production of antioxidant metabolites, preventing lipid peroxidation. Therefore, despite some repression of photosynthetic pa- rameters by WS, they did not compromise plant growth, and plants increased their antioxidant capacity. Our data demonstrate that M. azedarach juvenile plants have the potential to acclimate to water shortage conditions, opening new perspectives to the use of this species in reforestation/afforestation programs of drought prone areas. Ó 2014 Published by Elsevier Masson SAS. 1. Introduction Increased climatic variability is resulting in an increase of both the frequency and the magnitude of extreme climate events, and it is expected to lead to increasing drought areas (Climate Change 2007, 2007). In forestry, the identification/development of drought-tolerant species/genotypes is required for preserving yields and for recovering endangered areas. Drought is often associated with reduction of plant growth and yield [e.g. (Brito et al., 2003; Dias and Brüggemann, 2010)]. Drought also invari- ably leads to the accumulation of reactive oxygen species (ROS), which causes oxidative stress damages to plants (Silva et al., 2013). ROS can directly attack the membrane lipids, inactivate enzymes and damage the nucleic acids leading, in some cases, to cell death [e.g. (Silva et al., 2013; Dias et al., 2011)]. As a protection against ROS, plants have evolved an efficient defence system, with anti- oxidant enzymes and non-enzymatic compounds that can neutralize free radicals and reduce the potential damages of ROS (Silva et al., 2013; Dias et al., 2011). Melia azedarach, usually known as melia, cinamomo or china- berry tree, is native to West Asia and is one of the most used plants in traditional medicine due to several medicinal properties (Orhan et al., 2012). Extracts from different parts of M. azedarach are re- ported to exhibit antifungal, antihelmintic, nematicidal, diuretic, cytotoxic, antiproliferative, insecticidal and antioxidant activities (Husain and Anis, 2009). The tree produces valuable timber that is often used to make furniture, plywood, toys and fuelwood (Husain and Anis, 2009). The wide range of adaptability and its usefulness make M. azedarach an interesting candidate species for reforesta- tion and afforestation programmes of degraded areas. Considering that several medicinal species are known to have a great antioxidant activity and that abiotic stress conditions stimu- lates the antioxidant battery (e.g. ROS-detoxifying enzymes and antioxidant metabolites) in several plant species [e.g. (Silva et al., 2013; Fini et al., 2012)], we hypothesize here that M. azedarach may adapt to water stress conditions, by stimulating its antioxidant Abbreviations: A, net CO 2 assimilation rate; APX, ascorbate peroxidase; AsA, ascorbate; Cars, carotenoids; CAT, catalase; Chl, chlorophyll; C i , intercellular CO 2 concentration; CMP, cell membrane permeability; DHA, dehydroascorbate; DW, dry weight; E, transpiration rate; F v , variable fluorescence; F v /F m , maximum quantum yield of photosystem II; G-POX, guaiacol peroxidase; GR, glutathione reductase; gs, stomatal conductance; GSH, glutathione; GSSG, oxidized glutathione; H 2 O 2 , hydrogen peroxide; PS, photosystem; ROS, reactive oxygen species; SOD, super- oxide dismutase; WS, water stress; WW, well watered; F PSII , effective quantum efficiency of PSII; j, water potential. * Corresponding author. Tel.: þ351 234 370 200. E-mail address: csantos@ua.pt (C. Santos). Contents lists available at ScienceDirect Plant Physiology and Biochemistry journal homepage: www.elsevier.com/locate/plaphy 0981-9428/$ e see front matter Ó 2014 Published by Elsevier Masson SAS. http://dx.doi.org/10.1016/j.plaphy.2013.12.014 Plant Physiology and Biochemistry 75 (2014) 123e127