BIOLOGIA PLANTARUM 53 (3): 523-529, 2009 523 Contractile roots are the most sensitive organ in Crocus sativus to salt stress S.M. RAJAEI*, V. NIKNAM* 1 , S.M. SEYEDI**, H. EBRAHIMZADEH* and K. RAZAVI** Department of Plant Biology, School of Biology, University College of Science, University of Tehran, 14155-6455, Tehran, I.R.. Iran* Department of Plant Biotechnology, National Institute for Genetic Engineering and Biotechnology 14155-6343, Tehran, I.R. Iran** Abstract Crocus sativus corms were grown in Perlite and watered by half-strength modified Hoagland nutrient solution containing 0, 50, 100, 150, 200 mM NaCl. Growth parameters and contents of proteins, proline, polyphenols, minerals and saccharides were studied in fibrous roots, contractile roots, corms and leaves. All plants remained alive and did not display any sign of foliar damage even at 200 mM NaCl. However, the salinity decreased growth, relative water content and increased contents of proline and Na + in all organs. Total protein content was increased in corms and contractile roots but decreased in fibrous roots. Changes in protein pattern were also observed. Polyphenol content was increased by salinity in all organs except the leaves. As salinity increased, content of soluble saccharides decreased except in the contractile roots. Additional key words: hydroponic culture, NaCl, polyphenols, proline, protein, saffron crocus, sugars. Introduction Salinity affects almost all plant functions (Greenway and Munns 1980) and results in a wide variety of physio- logical and biochemical changes in plants (Yancy et al. 1982). Because of severe damages of plant growth and development, considerable attempts have been made in discovering physiological and biochemical processes contributing to adaptation to salinity in plants (Ashraf and Harris 2004). Some of these processes include osmotic adjustment by accumulation of compatible solutes (e.g. Tripathi et al. 2007) or soluble saccharides, and changes in regulatory mechanism for ion transport (e.g. Agarwal and Pandey 2004). The contents of proline, saccharides and proteins will provide potential biological markers useful in the identification and genetic manipulation of salt resistant plants (Shonjani 2002). Moreover, there is accumulating evidence that production of reactive oxygen species (ROS) is a major damaging factor in plants exposed to different environmental stresses, including salinity (Hernandez et al. 1995). The aim of this study was to investigate the changes in growth parameters, relative water content, contents of proteins, proline, polyphenols, K + , Na + and saccharides in different organs (fibrous roots, contractile roots, corms and leaves) of C. sativus, when subjected to NaCl stress. According to our knowledge, this is the first study on salinity induced physiological and biochemical changes in C. sativus. ⎯⎯⎯⎯ Received 29 March 2007, accepted 24 February 2008. Abbreviations: MS - Murashige and Skoog; RWC - relative water content; ROS - reactive oxygen species; SDS - sodium dodecyl sulfate. Acknowledgements: The authors acknowledge the financial supports of University College of Science and Research Council University of Tehran. The authors wish to thank the anonymous reviewer for improving the manuscript. 1 Corresponding author; fax: (+98) 21 66405141, e-mail: vniknam@khayam.ut.ac.ir