外源钙对盐胁迫下草木樨(Mellilotus officinalis L.)叶片超微结构的影响

Effects of Exogenous Calcium on Ultrastructure of Leavesin Mellilotus officinalis L. under Salt Stress

以草木樨(Mellilotus officinalis L.)为研究对象,观测了外源钙离子(0、10、20mmol/L CaCl2)对盐胁迫下(0、50、100、150、200 mmol/L NaCl),草木樨叶片表皮细胞、气孔特性、表皮毛形态结构的影响.结果表明,当Na^+浓度不超过100 mmol/L时,叶表皮细胞、气孔及表皮毛形态结构与对照组相比无明显改变.当Na^+浓度超过150 mmol/L时,表皮毛出现明显损伤,表皮细胞及气孔下腔分泌物明显增多,气孔趋于关闭.外源Ca^2+对盐胁迫下草木樨叶片的损伤具有一定的缓解作用,维持细胞正常的形态结构,提高气孔密度和气孔指数,有效地减小盐胁迫的伤害,增强了植物的耐盐性.尤其是10 mmol/L Ca^2+的保护作用优于20 mmol/L Ca^2+,较高浓度的Ca^2+也会对植物造成胁迫.因此,采用外源Ca^2+增强植物耐盐性时,应根据植物特性,选择适宜浓度,避免造成双重胁迫.

In the present study,the effects of calcium chloride(0,10 and 20 mmol/L CaCl2)on Mellilotus officinalis epidermal cell,stomata and epidermal hair under various levels of salt stress(0,50,100,150 and 200 mmol/L NaCl)were investigated.The results showed that there were no significant differences between the treatment groups and the control in epidermal cells,stomata and epidermal hairs ultrastructure when Na^+concentrations did not exceed 100 mmol/L.Epidermal cells were significantly damaged,cell secretion from epidermal cells and stomata increased and the stomata tended to close when Na+concentrations were more than 150 mmol/L.Exogenous of Ca^2+could protect M.officinalis against salt stress,maintain the normal morphology of cells,and increased the stomata index and stomata density.Ca^2+could efficiently reduce the damage caused by salt stress and help to improve salt tolerance in M.officinalis.Especially,the protection of 10 mmol/L Ca^2+was better than that of 20 mmol/L Ca^2+.The more concentration Ca^2+also caused stress on the plant.Therefore,in order to avoid Na+and Ca^2+double stress,the appropriate application of exogenous Ca^2+should be selected to improve the salt tolerance of plant according to the plant characteristics.