Effects of drought stress on biochemical and physiological parameters in callus cultures of <i>Carthamus tinctorius</i> varieties
2010
The aim of the work was to evaluate the callus induction response and <i>in vitro</i> drought tolerance of eight genotypes of safflower. The experiment was laid out as a completely randomized design in a factorial arrangement with three replications. To evaluate the drought tolerance of the genotypes, growing calli were exposed to drought stress after two subcultures by adding different concentrations of mannitol to the culture medium for one month. Under stress conditions, the genotypes were compared in terms of proline content, cell viability, relative growth rate, ion content (Na<sup>+</sup> and K<sup>+</sup>), relative water content and index of tolerance. Drought affected all the measured biochemical and physiological factors and there were significant differences between the tested genotypes. The proline content increased in drought-stressed calli, and mannitol, as a stress agent, stimulated the synthesis of proline in all the genotypes, especially at the highest concentration (505 mM), whereas the ion contents, cell viability, RWC, RGR and index of tolerance exhibited a significant decrease. This suggested that these biochemical and physiological traits could be used to predict the drought tolerance of safflower genotypes. The results indicated that the cultivars Isfahan and LRV-51-51 were more drought-tolerant under <i>in vitro</i> conditions than the other genotypes.
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