Asparagine이 水稻 幼苗期 耐鹽性 향상에 미치는 영향

Effect of asparagine on enhancement of salt tolerance at seedling stage in rice

This study was designed to examine whether salt tolerance was enhanced in rice by exogenous asparagine. Germination and the establishment on sterile seedlings were increasingly inhibited by NaCl concentrations from 40 to 120 mM. At 200 mM NaCl, plant growth of wild type was completly blocked. Seedling establishment was prevented at 20 mM asparagine. At lower concentration, exogenous asparagine enhanced NaCl resistance during germination and seedling establishment. Inhibition of seedling establishment by NaCl concentration below 200 mM was reduced by the addition of asparagine to the medium. Maximal reduction of NaCl inhibition occurred between 2 and 4 mM for asparagine. Higher concentrations of NaCl prevented establishment whether exogenous asparagine was present or not. The total seedling content of Na⁺ increased about 9-fold at 200 mM NaCl. Asparagine had no effect on the K⁺ content per unit dry weight of seedlings grown on media containing increased levels of NaCl. The ratio of Na⁺/Ca⁺⁺, Na⁺/K⁺ increased at a high rate on media containing increased levels of NaCl. The present results indicate that the asparagine enhance the salt tolerance at seedling stage in rice. Relationship between free amino acid accumulation and saline tolerance is discussed.