Cumulative Effects of Seawater Stress on Cell Damage of Mesembryanthemum crystallinum L. and Small Organic Molecules of Osmoregulation Substances

【Objective】The objective is to explore the cumulative effects of seawater stress on the cell damage of Mesembryanthemum crystallinum L., proline, soluble sugar and betaine.【Method】A pot experiment was conducted on M. crystallinum L. to study the changes of cells damage（MDA and cell membrane permeability） and small organic molecular osmoregulation substances （soluble sugar, betaine and proline） with seawater stress at different concentrations （20%, 30%, 40%, 50%, 60%）. 【Result】With the increase of seawater concentration: the permeability of cell membranes and the content of soluble sugar were enhanced in each branch of M. crystallinum L. ;MDA and the content of betaine increased in the first and second branches, and increased and then decreased in tertiary branches; and the content of proline increased and then decreased in all branches. A significant positive correlation was discovered between seawater stress and the permeability of cell membranes and the content of soluble sugar. For small organic molecules osmoregulation substances, only the content of soluble sugar had a significant positive correlation with concentration of seawater and lipid peroxidation of membranes. 【Conclusion】With the increase of seawater concentration, the damage of M. crystallinum L. cell membrane is aggravated. Soluble sugar, betaine and proline play an important role in osmotic regulation in different seawater concentrations and different growth stages. Moreover, their correlationwith seawater stress is as follows: soluble sugar > betaine > proline.