The Effect Of Exogenous Nitric Oxide On Typha Angustifolia Seedling Under Copper,Cadmium And Combined Stress

Typha angustifolia is a perennial emergent aqutaic plant which belongs to cattail family.It has commonly used in water configurations,with adsorption of heavy metal effect.Now,heavy metal pollution（Cu,Cd）caused serious damage on plant growth which increasingly serious.T.angustifolia plays a role in the repair of heavy metal pollution in water.Nitric oxide（NO）as a bioactive molecule,has been confirmed participating in most physiological processes involved in plant growth,including growth,development,resistance and so on.At present,the function of improving the resistance about NO on plant growth to heavy metal tolerance or sensitivity is different.T.angustifolia can highly resist heavy metals,but the application of NO on T.angustifolia has not been studied.In order to further investigation about the impact of NO on T.angustifolia resistance to heavy metal,this study adopted hydroponics to study the effect of NO sodium nitroprusside（SNP,NO donor）on T.angustifolia to verify whether NO can improve resistance ahout heavy metals,which provide scientific foundation about expand applications of T.angustifolia.The main findings are as follows:1.Effect of exogenous NO on T.angustifolia seedling under cadmium stressThis article studied the effect of 100 μM exogenous NO about photosynthetic pigments,antioxidant system,the content of nutrients and protein synthesis on T.angustifolia under 50 mg · L^-1 Cd²⁺ stress.The results showed that exogenous NO significantly added the content of chlorophyll,compared with Cd treatment.SNP treatment reduced MDA content and relative conductivity of T.angustifolia exposed to Cd stress.Exogenous NO under Cd stress had reverse effect on Cd-induced increase in activies of SOD activity,and also increased POD activity but the difference was not significant.Exogenous NO could increase AsA content in different parts of T.angustifolia and reversed GSH content increased by Cd stress in root.The induction of Cd on the non-protein thiol（NPT）and phytochelatins（PCs）contents in root can also been reversed by NO.NO enhanced Cd allocation in cell wall of root and reduced Cd distribution in cell wall,organelle and soluble fraction of leaf.Exogenous NO increased the content of K,Mg,Cu and Fe in leaves and significantly decreased the content of K Mg and Mn in roots exposed to Cd.Exogenous NO promoted the expression of protein bands which molecular weight between 12-50 kDa protein bands in leaves and relieved Cd-induced the decrease content of protein bands in sheathes.In root,NO increased the expression of protein bands which molecular weight between 20-25 kDa,but inhibited the expression of protein bands with molecular weight between 12-20 kDa.2.Effect of exogenous NO on T.angustifolia seedling under copper stressThis article studied the effect of 100μM exogenous NO about photosynthetic pigments,antioxidant system,the content of nutrients and protein synthesis on T.angustifolia under 30 mg · L^-1 Cu²⁺ stress.The results showed that exogenous NO could relieve excess Cu-induced decrease of chlorophyll content which close to the control level;Adding NO significantly reduced MDA content in leave and root which also decreased conductivity in different tissues exposed to Cu stress;NO promoted the content of AsA and GSH in leave and sheath,which had no significant change in root under Cu stress;Applying NO promoted the content of K,Ca,Mg,Mn,Zn in leave,but inhibited the content K,Mn,Ca and Mg in root,and Ca,Zn content in sheath;Exogenous NO could trap the corresponding changes in the protein under Cu stress;Exogenous NO inhibited the expression of protein bands which molecular weight between 12-50 kDa protein bands and promoted the expression of 50 kDa protein bands in leaves;In opposite,many protein bands expression were inhibited in sheath;In root,exogenous NO promoted the expression of 12 kDa protein bands,but inhibited the expression of protein bands which molecular weight between 20-30 kDa protein bands under Cu stress.3.Effect of exogenous NO on T.angustifolia seedling under copper and camdium combined stressThis article studied the effect of 100 μM exogenous NO about chlorophyll,antioxidant system,the content of nutrients and protein synthesis on T.an.gustifolia under 30 mg · L^-1 Cu²⁺ + 50 mg · L^-1 Cd²⁺ stress.Applying NO significantly increased content of chlorophyll exposed to combine.NO could decreased relative conductivity in leave which also decreased MDA content in leave and root.Under combined stress,SOD activity significantly increased by NO in leave,and SOD and POD activity reduced by NO in root.Exogenous NO significantly increased Cu,Cd content in underground part which significantly reduced Cu,Cd content in aboveground.Applying NO promoted the content of K in leave and Zn content in root,but decreased the content of Ca in sheath and K,Mn content in root.Exogenous NO could increase Cd content in cell wall and organelle of root,which reduced the Cd content of various subcellular fractions in leave and sheath,and also decreased Cu content in the soluble portion of leave.Under Combined Stress,inhibiting the expression of protein bands which molecular weight between 12-30 kDa protein bands and promoted the expression of 50 kDa protein bands in leaves.NO promoted the expression of protein bands which molecular weight between 35-85 kDa protein bands in sheath.NO induced the the expression of protein bands in root.