The Effect Of Nitrie Oxide On Root Morphology And Antioxidant System In Pisum Sativum Seedings Under Iron Stress

As an essential micronutrient element,iron participates in a great deal of enzymatic reactions and electron transfer in photosynthesis and respiration processes.Owing to lack of soluble ferric compounds in soil and removability of iron in plant,chlorosis of plants and human anemia often occurded in spite of abundant iron in soil.Studies on enhancing the activation and utilization eficiency of iron,and adaptive and regulatory mechanisms of iron deficiency in plants are becoming one of focuses in plant nutriology currently.Nitric oxide(NO) plays an important role in growth and development of plants, for examples,in germination of seeds,expandability of leaves,de-etiolation of yellowing seedlings,and redox reactions in plants.Recently,NO was suggested to function as a new signaling molecule in plants.In this study,we aimed to examine the efects of NO on iron metabolism of plants under iron stress,and the relations between NO,iron,and redox system.The results showed that NO could promote the development of shoot and improve crown-root ratio in iron deficient pea seedlings,increase the elongation of root system and promote evelopment of branch root.NO treatment could alter the activities of antioxidant defense system in iron deficiency and iron toxic seedling With iron deficiency becoming serious,SNP up-regulated the activities of SOD,CAT while APX decreased significantly and the contents of MDA,O₂^-,H₂O₂ down to the normal physiological level.With iron deficiency becoming serious,SNP up-regulated the activities of SOD,CAT and APX decreased significantly,and the contents of MDA,O₂^-,H₂O₂ to the normal physiological level.Fe³⁺ reductase activity had also been measured under exogenous NO in this study.Experiments proved that treatment of different iron concentration of iron cloud change the Fe³⁺ reductase activity in roots of pea seedlings,However,NO can improve the Fe³⁺ reductase activity.