Effects Of Exogenous Nitric Oxide On Photosynthesis And Antioxidant Protection System Of Polygonatum Odoratum(Mill.) Druce Under Salt Stress

Polygonatum odoratum?Mill.?Druce is a perennial herb of Liliaceae,which is widely distributed in Northeast China,North China and Northwest China.It is mainly grown in Heilongjiang Province to grow in arid and sandy soil-dominated meadow steppe,which has strong resistance to abiotic stress.It has a high ornamental value,its leaves thick green,flowers chic elegant,It can not only as a Chinese herbal medicine,or a good garden ground cover plants,they grow together,the ground cover effect is excellent,great development value.To expand its use in saline soil,in this study,the rhizome of Polygonum cuspidatum was selected as the experimental material,to study the effects of exogenous Nitric Oxide on photosynthesis and antioxidant protection system of Polygonatum odoratum?Mill.?Druce under salt stress.Get the following conclusions:?1?With the increase of NaCl concentration,the relative water content of leaves of Polygonatum odoratum decreased gradually,and the degree of succulence of leaves increased first and then decreased.After exogenous NO was applied,the relative water content of leaves of Polygonatum odoratum could be increased and this trend increases with increasing SNP concentration.When SNP is not more than 100?mol·L^-1,the application of NO can improve the meat quality of Polygonatum odoratum.Indicating that the application of NO at a certain concentration can alleviate the damage caused by salt stress,keep the moisture content in the leaves,and maintain the water level in the plants.?2?With the increase of NaCl concentration,the content of malondialdehyde?MDA?in leaves of Polygonatum odoratum increased with the increase of salt concentration,and root activity is the first to increase the trend after the lower.NO(SNP?100?mol·L^-1)could decrease the accumulation of MDA in leaves of Polygonatum odoratum,and improve the root activity of Polygonatum odoratum.?3?Salt exchange of bamboo gas exchange parameters also have an impact.With the increase of NaCl concentration,the net photosynthetic rate,stomatal conductance and transpiration rate of Polygonum multiflorum decreased gradually,while the intercellular carbon dioxide concentration appears to decrease first and then rise again and then decrease the volatility of the change again,and the concentration of carbon in the NaCl concentration of 150 mmo l / L significantly higher than other groups.Indicating that exogenous NO can alleviate the inhibition of salt stress on photosynthesis.But the high concentration of NO?SNP?150?mol / L?on the gas exchange parameters related to the role of indicators is less significant,and even the performance of inhibition.?4?Polygonatum leaves osmotic adjustment substances such as soluble sugar,soluble protein,proline,etc.)content with the increase in NaCl concentration and accumulation,and when exogenous NO?SNP?100?mol / L?was applied,the osmolytes increased.High concentration of NO?SNP> 100?mol / L?on the accumulation of osmotic adjustment of the role of the promotion is less obvious.?5?The content of ASA and GSH decreased with the salt concentration under NaCl stress.NO(SNP?100?mol·L^-1)could increase the activity of SOD,GPX,CAT and APX at low salt concentration(NaCl?150 m mol·L^-1).This trend increased with the increase of SNP concentration,while promoting ASA and GSH content accumulation;NO(SNP> 100?mol·L^-1)had different inhibitory effects on antioxidant enzymes in leaves of Polygonatum odoratum,NO had an effect on the process of ROS removal of Polygonum multiflorum by antioxidant enzymes.The contents of ASA and GSH increased with the increase of NO concentration,but the effect of NO on the anti-oxidative protective enzyme was not obvious when the concentration of NO was higher than that of the control group(NaCl> 150 m mol·L^-1).The results showed that NO(SNP?100?mol·L^-1)could effectively reduce the accumulation of ROS in the body and maintain the normal metabolic activity of Polygonatum odoratum.Under high salt stress(NaCl> 200 m mol·L^-1),the effect of SNP was not obvious,and the activity of antioxidant enzymes was not inhibited.Compared to non-enzymatic antioxidants ASA and GSH,antioxidant enzymes play a more prominent role in the removal of excess ROS in the body,while the exogenous NO can improve the content of nonenzymatic antioxidants in Polygonum multiflorum,and participate in the balance of mediating ROS.