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 CO2 assimilation rate (A) and the intercellular CO2 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 parameters 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.
Subject(s)
Acclimatization , Antioxidants/metabolism , Droughts , Melia azedarach/physiology , Photosynthesis , Stress, Physiological , Water , Carbon Dioxide/metabolism , Chlorophyll/metabolism , Lipid Peroxidation , Melia azedarach/growth & development , Melia azedarach/metabolism , Photosystem II Protein Complex/metabolism , Plant Leaves/metabolism , Plant Stomata , Plant Transpiration , Trees , Up-RegulationABSTRACT
Paradise tree (Melia azedarach L.) is a multipurpose ornamental and timber tree, and its extracts are used to make insecticides and fungicides. Conventional propagation is done by seeds; however, sexual reproduction results in wide genetic variability. Therefore, clonal propagation is desirable to reduce genetic variation. This chapter describes a protocol for in vitro propagation of paradise tree by axillary buds. There are major steps for this protocol. Firstly, shoot induction by in vitro culture of axillary buds, excised from potted plants obtained by rooting of cuttings of 10-15-year-old adult trees. The initiation medium was composed of Murashige and Skoog medium (MS) supplemented with 0.5 mg/L BAP (benzylaminopurine), 0.1 mg/L IBA (indolebutyric acid), and 0.1 mg/L GA(3) (gibberellic acid). Secondly, multiplication of the regenerated shoots on MS medium amended with 0.5 mg/L BAP and 0.1 mg/L GA(3). Thirdly, rooting of the regenerated shoots on MS medium containing 0.1 mg/L IBA. Fully well-developed plants were transferred to pots containing sand, peat moss, and perlite (1:1:1), and maintained initially in the greenhouse or plastic tunnels.
