Nitric Oxide Alleviates The Damage And Promotes The Absorption And Transport Of Phosphorus Under Acid Rain Stress In Arabidopsis Thaliana

Acid rain has many potential effects on terrestrial ecosystems and has a direct impact on crops and forests.As a regulator of plant growth and development,NO regulates cells in different forms at different stages of plant growth.It is mainly manifested in that NO reduces the degree of lipid peroxidation and increases the ability of antioxidation,thus reducing the severity of oxidative stress in plants.Phosphorus is an essential element for plant life activities and essential for cellular components,including nucleic acid,membrane and ATP,and is a key component in regulating enzyme reaction,metabolic pathway and signal transduction.The pathway of phosphorus absorption and transport has been proposed,through the regulation of PHR1 and miR399,inhibit the accumulation of PHO2,low concentration of PHO2can promote the expression of PHT1 and PHO1,in which PHT1 gene family is mainly responsible for phosphorus uptake in Arabidopsis thaliana,and PHO1 gene family is mainly involved in phosphorus transport from root to stem.In this study,wild-type Arabidopsis thaliana,nia1nia2 mutant with low endogenous NO content and nox1 mutant with high endogenous NO content were used as materials to study the effects of NO on phosphorus uptake and transport in Arabidopsis under acid rain stress.Under acid rain stress,the contents of malondialdehyde,proline and H₂O₂increased significantly.When exogenous NO was added,the contents of malondialdehyde,proline and H₂O₂decreased significantly,and the contents of malondialdehyde,proline and H₂O₂increased significantly after NO removal,indicating that exogenous NO could alleviate membrane damage and membrane peroxidation caused by acid rain stress.Through the external application and scavenging experiments of NO,it is proved that exogenous NO can inhibit the accumulation of soluble sugar and reduce the loss of water in leaves under acid rain stress.NO can alleviate the increase of ion permeability of plants under acid rain stress and protect the membrane to a certain extent.By comparing the changes of malondialdehyde,proline,H₂O₂,soluble sugar,water content and ion permeability of nia1nia2 mutants with lower endogenous NO content and nox1 mutants with higher endogenous NO content under acid rain stress,as well as their comparison under different conditions,the results showed that high content of endogenous NO could alleviate the damage caused by acid rain stress.NO could slow down the decrease of the expression of miR399,PHR1,PHT1.1,PHT1.4 and PHO1 under acid rain stress,and increase the expression of PHO2.The prediction of S-nitrosation sites showed that there were cysteine sites on the amino acid sequences of miR399,PHR1,PHT1.1,PHT1.4 and PHO2,which provided binding sites for S-nitrosation of NO.Therefore,we speculate that under acid rain stress,NO alleviates the membrane damage of plants under acid rain stress through the absorption and transport of phosphorus,which provides some basis for NO to participate in plant stress resistance.