Uticaj salicilne kiseline na biohemijske mehanizme tolerancije Impatiens walleriana (Balsaminaceae) prema vodnom stresu
Effect of salycilic acid on biochemical tolerance mechanisams of Impatiens walleriana (Balsaminaceae) to water stress
Abstract:
In the first part of dissertation the responses of Impatiens walleriana to polyethylene glycol (PEG) induced water stress and the potential of exogenous salicylic acid (SA) as stress-ameliorating agent was described. Impatiens shoot culture was established on medium containing different concentrations and combinations of PEG (1–3% ) and SA (1–3 mM). After prolonged drought, water relation parameters, oxidative stress indicators, and growth responses of the shoots to PEG and/or SA were recorded. PEG reduced growth, fresh weight of shoots, the number of developed leaves and shoots, relative water content (RWC), and chlorophyll content. PEG caused accumulation of proline, H2O2, and malondialdehyde (MDA). The activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POX) were increased in response to PEG in a dose-dependent manner. In the second part of dissertation it was investigated whether the foliar application of 2 mM SA could protect ex vitro grown I. walleriana plants from drought stress. The plants were divided into 4 groups: watered plants, drought-stressed plants, watered plants treated with SA and drought-stressed plants treated with SA. The number of flower buds and flowers, RWC, contents of MDA, proline and the activities of superoxide dismutases, catalases and peroxidases were recorded at different time points. Three dehydrin sequences were identified in de novo assembled leaf transcriptome: IwDhn1, IwDhn2.1 and IwDhn2.2. Drought stress caused wilting, floral abortion, reduction of RWC and increased MDA. In response to drought, I. walleriana induced chloroplastic Cu/ZnSOD and two guaiacol peroxidase isoforms. The remarkable drought response was induction of IwDhn2.1 and IwDhn2.2. SA had ameliorating effects on plants exposed to drought, including prevention of wilting, preservation of RWC, modulation of antioxidative activities, but had no effects on flowers preservation.