PHYSIOLOGICAL ASPECTS OF RICE CALLUS GROWTH AND PLANT REGENERATION IN A MODIFIED MS MEDIUM SUPPLEMENTED WITH NaCl

摘要

Salt tolerance of four Iranian rice cultivars were evaluated in vitro using modified MS medium supplemented with six levels of NaCl (0, 20, 40, 60, 80 and 100 mM). Fresh weight, dry matter, water content, Na~+, K~+, Ca~(2+) and Cl~(-1) ions and proline content of callus as well as plant regeneration percentage were measured. When NaCl content of the medium was increased from 0 to 20 mM fresh weight of callus and plant regeneration increased from 382.6 mg and 59% to 437.8 mg and 63%, respectively, andthereafter, rapidly decreased. The callus induction and growth as well as plant regeneration were found to be maximum on MS medium containing 20 mM NaCl supplemented with 2.0 mg l~(-1) 2, 4-D (9.04 uM) and 0.2 mg l~(-1) BAP (8.88 uM) (for callus induction) and medium with 3 mg l~(-1) NAA (16.11 uM), 2 mg l~(-1) kinetin (9.3 uM), 50 mg l~(-1) tryptophan, respectively. Also, results showed that proline accumulation in callus was negatively correlated with the fresh weight and water content and was not correlated with Na`+ and Cl~- ion contents of the callus. Path coefficient analysis based on correlation matrix showed that Ca~(2+) and K~+ ions, which remained positively correlated with fresh weight and water content, affected fresh weight via their effects on water content. Proline, Na~+ and Cl~- ions had negatively influenced the water content of callus. It is concluded that 'Zayandeh Roud' cultivar due to its evaluated callus growth and plant regeneration on NaCl containing medium might be an appropriate candidate to be transformed by genes that enhance the rice salt tolerance.