Regulation Of ROS And NO On Aerenchyma Formation Of Potamogeton Perfoliatus

Pogeton perfoliatus is a perennial submerged plant.Its roots,stems and leaves evolve into well-developed aerenchyma to adapt to the hypoxic environment under water.Currently,it is known that the formation of aerenchyma in aquatic plants is the result of programmed cell death(PCD)induced by hypoxia,but the mechanism of Reactive oxygen species(ROS)and nitric oxide(NO)interacting in complex signal networks to regulate the pathogenesis of aerenchyma is unclear.In this experiment,submerged plant P perfoliatus was used as the material.Using semi thin sectioning technology,exogenous NADPH oxidase inhibitor Dibenziodolium chloride(DPI),Catalase(CAT)inhibitor Triazol-3-amine(AT),NO donor Sodium Nitroferricyanide(Ⅲ)Dihydrate(SNP),and NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt(PTIO)were added to treat P perfoliatus.Physiological and biochemical indicators such as ROS content,NO content,ROS and NO synthesis related enzyme activity were measured and analyzed,and to compare and study the dynamic changes in cellular morphology and structure during the development of developmental aerenchyma and exogenous ROS and NO induced aerenchyma in P perfoliatus at the microstructural level,and to explore the effects of ROS and NO signaling molecules on the aerenchyma formation and their physiological regulatory mechanisms.The following results were obtained.Exogenous DPI treatment can reduce the accumulation of endogenous ROS and NO in plants,inhibit the formation of aerenchyma,and exogenous AT can increase the accumulation of endogenous ROS and NO in plants,promoting the formation of aerenchyma,the epidermis of AT 100 μmol/L treatment group shrunk and folded inward to a large extent,resulting in a very irregular shape of the stem compared with CK and other treatment groups,indicating that ROS has a positive regulatory effect on the formation of aerenchyma,and excessive ROS accumulation will have a certain negative effect on plants.By applying exogenous inhibitors of ROS metabolic enzymes,it was found that they not only affect endogenous ROS,but also affect endogenous NO content,suggesting that ROS and NO interact to jointly regulate the development of aerenchyma.After NADPH oxidase is inhibited and ROS in plants is cleared,the content of NO is significantly inhibited.However,after increase ROS in plants by inhibiting CAT enzyme activity,the content of NO is also significantly increased,indicating that endogenous ROS in plants may induce the production of endogenous NO in plants.Exogenous SNP treatment can increase the accumulation of endogenous NO in plants and reduce the accumulation of ROS,promoting the formation of aerenchyma.Exogenous PTIO can reduce the accumulation of endogenous NO in plants and increase the accumulation of ROS,inhibiting the formation of aerenchyma,indicating that NO has a positive regulatory role in the formation of aerenchyma.Through the exogenous application of NO donors and inhibitors,it was found that not only endogenous NO but also endogenous ROS content were affected,suggesting that ROS and NO interact to jointly regulate the development of aerenchyma.After exogenous SNP was applied to increase NO in plants,the activities of superoxide dismutase(SOD),peroxidase(POD),CAT increased,and the content of ROS significantly decreased.However,after exogenous PTIO was applied to eliminate NO in plants,the activities of SOD,POD,CAT decreased,and ROS accumulated in plants,indicating that exogenous NO application can activate the activity of antioxidant enzymes,regulate the level of endogenous ROS in plants,improve the tolerance of plants to oxidative stress,and have an important role in plant growth and developmentExogenous DPI+PTIO treatment can reduce the accumulation of endogenous ROS and NO in plants and inhibit the formation of aerenchyma.On the contrary,exogenous AT+SNP treatment can increase the accumulation of endogenous ROS and NO in plants and promote the formation of aerenchyma.While exogenous AT+PTIO or DPI+SNP treatments can respectively induce the accumulation of endogenous ROS in plants while inhibiting the accumulation of endogenous NO in plants,or inhibit the accumulation of endogenous ROS while inducing the accumulation of NO in plants,without significant impact on the formation of aerenchyma,indicating that ROS and NO regulate the formation of aerenchyma not solely,but through interactions in complex signal networks that jointly regulate the formation of aerenchyma.The physiological mechanism of ROS and NO synergistically regulating the aerenchyma development is to change the accumulation of endogenous ROS and NO in plants by changing the activities of ROS-related enzymes,such as SOD,POD,CAT,and NO synthase,such as nitric oxide synthase(NOS)and nitratase(NR),thereby regulating the development of aerenchyma.