Saline (NaCl) stress in germinated seedlings of rice cv. Rupsail causes an increase in polyamine content and concomitantly an enhancement of arginine decarboxylase (ADC) activity; in the case of putrescine, the increase is 100%. The responsiveness of coleoptiles and roots is different; ADC activity is maximum in roots and coleoptiles at 50 mM and 100 mM respectively. Difluoromethyl arginine, a potent inhibitor of ADC, reduces both polyamine accumulation and ADC activity. NaCl can enhance the activity of ADC by 1.6-fold in vitro. [14C]leucine incorporation into protein at 400 mM NaCl is decreased 4- and 10-fold in coleoptiles and roots, respectively. Efflux of sugar, amino acid, polyamines and total electrolytes increased gradually with the increase in concentration of salt. Influx of Na+ and Cl- and efflux of K+ in coleoptiles and roots are directly proportional to the concentration of NaCl applied.

1991. Polyamines in various rice {Oryza sativa) genotypes with respect to sodium chloride salinity. ~ Physiol. Plant. 82: 575-581.Physiological responses of various rice genotypes were studied in relation to salt (NaCl) stress. Culfivars CSR-I and Dular germinated well in different NaCl regimes compared to cvs Rupsail. Assam Getu and M-1-48. At 100 mM NaCl, the lowest germination was observed in cv. M-1-48. Cvs CSR-1 and Dular were relatively effective in maintaining, high concentrations of polyamines as well as arginine decarboxylase (EC 4.1.1.19) activity in coleoptiies and roots in a non-stressed condition. The activities of two biodegradative enzymes, diamine oxidase (EC 1.4.3.6) and polyamine oxidase (EC 1.4.3.4), were lowest in cv. CSR-1. The polyamine content was not significantly altered when seedlings of cv. CSR-1 were exposed to 100 mM NaCl. However, in cv. M-1-48 enhancement of arginine decarboxylase activity with concomitant accumulation of polyamines was observed. Leakage of metabolites and changes in the levels of Na* and Cr were prominent in cv. M-1-48 under saline conditions. The results suggest a correlation between polyamine and salt stressinduced responses in rice genotypes.