Please use this identifier to cite or link to this item: http://prr.hec.gov.pk/jspui/handle/123456789/1552
Title: MOLECULAR AND BIOCHEMICAL ANALYSES OF CROSS ADAPTATION MECHANISM(S) FOR SALT TOLERANCE IN RICE (Oryza sativa L.) CELL LINES
Authors: SHAH, AZHAR HUSSAIN
Keywords: Natural Sciences
Biology
Biotechnology
Genetics & evolution
Issue Date: 2009
Publisher: NWFP AGRICULTURAL UNIVERSITY PESHAWAR, PAKISTAN
Abstract: In the present research work cell lines of Oryza sativa cv. Swat-1 were incrementally adapted to osmotic (20 % PEG) and ion toxicity (20 mM LiCl) stresses to study the mechanisms of sequential tolerance and cross adaptation. The adapted cell lines were growing on respective stresses over a period of 55 passages and their tolerance was stable at least up to 6th generation on stress free medium. The physiological characterization of cell lines showed a substantial increase in proline and Ca++ levels and significant reduction in K+ and Mg++ contents on adaptation to PEG stress, while no prominent differences in accumulating organic and inorganic cytosolutes were observed between unadapted and LiCl adapted cell lines. Adaptation to PEG and LiCl was evident by appearance of six different polypeptides, among these four polypeptide bands 15, 17, 26 and 68 kDa were common, while, other two novel proteins 60 kDa, and 32 kDa were unique to PEG and LiCl adapted cell lines, respectively. None of these polypeptide were detectable in unadapted cell lines. At the molecular level the PCR amplification results using seven set of SSR primers for saltol region of chromosome 1 of rice revealed no polymorphism in adapted and unadapted cell lines. When adapted and unadapted cell lines were exposed to 200 mM NaCl with an iso-osmotic effect to 20 % PEG and an osmotic effect 10 times higher than 20 mM LiCl in addition to toxicity effects for two consecutive passages. The tolerance of both adapted lines was similar but significantly greater than tolerance of unadapted cells line. On exposure to subsequent second NaCl stress unadapted cells line failed to survive but the tolerance of adapted cell lines increased, expressing the phenomenon of sequential tolerance. Overall, no qualitative differences were observed among adapted and unadapted cell lines under salt stress. However, the patterns of response of adapted and unadapted cell lines to osmotic and ionic homeostasis to tolerate NaCl were greatly different. PEG adapted cells line appeared to acquire halophytic behavior of a salt accumulator, in contrast LiCl adapted line behaved like a typical salt tolerant glycophyte. Furthermore, the induced tolerance of adapted lines were not restricted to the same type of stress but showed cross tolerance towards other abiotic stresses.
URI:  http://prr.hec.gov.pk/jspui/handle/123456789//1552
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