Changes of ionic content andcomposition of spinach leaf are differential in response to salinity in the presence or absence of K+ (Fig. 1 ). The content of glycinebetaine and the achvity ofbetaine aldehyde dehydrogenase(BADH)in spinach leaves treated with differentconcentrations of NaCl without K+ werelower than those with K+ (Figs. 2, 4).The content of glycinebetaine in thoseleaves cultured in Hoagland solutionwithout K+ was lower than that with K+(Fig. 3 ). Culturing seedling withHoagland soluhon without K+ or withTEA (tetraethylammonium chloride ) 10mmol/L, a K+ -channel inhibitor, alsoresulted in a lower BADH activity(Fig.5). The results here showed that K+may be involved in the regulation ofBADH activity and the accumulation ofglycinebetaine.
K~+, NaCl stress, glycinebetaine , betaine aldehyde dehydrogenase(BADH), spinach