Analyses of the early salt-induced changes of chemical composition in cultured ice plant cells

• Main Authors: kuo Fang Weng, 翁國峰
• Other Authors: Hungchen E. Yen
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/94800695510199511665

碩士 === 國立中興大學 === 生命科學院碩士在職專班 === 92 === Abstract This thesis is aimed at the early responses to salt stress in halophyte ice plant (Mesembryanthemum crystallinum L.). Tissue culture-grown ice plant cells were used in this study. Two-week-old cells were stressed with different concentrations of NaCl, NaCl plus KCl, or NaCl plus CaCl2 and in situ monitoring the changes of chemical composition using FT-IR. Within 1800 seconds, IR signal detected the rapid changes of proteins, acids and carbohydrates on the surface of ice plant cells. When cells were salt-stressed, the Na+ content inside the cells increased in accompanied with the decrease of K/Na ratio. The area of amide-II (1550 cm-1) band increased as the NaCl concentration increased suggesting the accumulation of extracellular proteins during salt stress. Colorimetric measurement of total extracellular protein content yielded the similar result as the IR measurement. SDS/PAGE and ConA affinoblotting analyses showed the accumulation of certain polypeptides as well as glycoproteins in the extracellular space of ice plant cells upon salt stressed. IR measurement also detected the changes of acids (around 1410 cm-1) and carbohydrates (around 1100 cm-1) but the alterations of these two cellular components were not as significant as that of proteins suggesting these two may not play immediate roles in the initial responses to salt stress. Under high NaCl condition, addition of K+ or Ca2+, the antagonists of Na+, decreased the area of amide-II band suggesting the accumulation of extracellular protein was slowed down. The results suggest that certain proteins may act on the decrease of cell extension rate at the early stage of salt stress to accommodate with the sudden increase of high Na+ in the environment and the growth of cell resume after the mechanism of osmotic adjustment has launched.