Effects Of Enhanced UV-B Radiation And TiO₂-NPs On Damage And Repair Of Wheat And Arabidopsis Thaliana

As the ozone hole in the North and South poles continues to increase,the entire ecosystem will face an environmental crisis caused by enhanced UV-B radiation.Plants,as the most important producers of the entire ecosystem,are vulnerable to enhanced UV-B radiation because of the characteristics of their growth patterns.Enhanced UV-B radiation can cause stress responses such as DNA breakage,accumulation of cyclobutane pyrimidine dimers（CPDs）,increased 6-4 photoproducts and reactive oxygen species（ROS）bursts,resulting in photosynthetic inhibition,reduced plant height,reduced leaf area,plant physiological changes,and severe plant death.Previous studies have shown that enhanced UV-B radiation causes abnormal mitotic"partition-bundle division"in wheat.Aurora kinase is an important protein in the regulation of mitosis and is involved in chromosome positioning,segregation,and cytoplasmic division during mitosis.Enhanced UV-B caused by the presence of abnormal division and Aurora kinases how to contact us to explore worth.The rapid development of nanotechnology has led to the application of nanomaterials in industrial and agricultural production and daily life.The impact of nanotechnology on the environment has also attracted more and more attention.The application of nanotechnology in plants to respond to UV-B stress and the impact of nanomaterials on plants are also topics of our interest.Previous studies have shown that Ti O₂-NPs can promote the synthesis of plant flavonoids and improve plant tolerance to stress.Whether the unique physical properties of Ti O₂-NPs can alleviate the damage of enhanced UV-B to plants is our concern.At the same time.In this study,Arabidopsis thaliana and wheat were used as materials.The transgenic Arabidopsis p AUR1:AUR1-GFP recovery line and p AUR1-GUS line were constructed.The subcellular localization of At Aurora1（At AUR1）was observed by laser confocal microscopy and the tissue expression pattern was observed by fluorescence microscopy.The p AUR1:AUR1-GFP and H2B-YFP were treated with UV-B radiation at doses of 3 k J/m²and 5k J/m²,and the effects of enhanced UV-B radiation on mitosis and At AUR1 were studied.It provides a theoretical basis for unraveling the molecular mechanisms underlying the production of"partition-bundle division".Through laser confocal microscope observation,RT-q PCR,histochemical staining and other methods,the process of Ti O₂-NPs alleviating plant UV-B stress was studied.Results were showed as followed:1.Mutant identification obtained AtAUR1 knockdown mutant line,compared with Col-0,the phenotype showed growth retardation phenotype.2.Successfully constructed AURs-related overexpression vectors,native-promoter vectors and GUS vectors,and obtained positive transgenic lines through the flower soaking method.3.The subcellular localization of AURs in tobacco and Arabidopsis was observed.AURs are involved in mitotic progression and are mainly expressed during division.4.Enhanced UV-B radiation affects the activity and localization of At AUR1,leading to abnormalities in the morphology and bipolar positioning of the spindle,and ultimately to the production of"partition-bundle division"during mitosis.5.TiO₂-NPs significantly alleviated the damage caused by UV-B radiation in plants,Ti O₂-NPs activated the antioxidant system of plants,increased the activity of antioxidant enzymes and promoted the synthesis of flavonoids.It effectively shields against UV-B radiation and prevents the depolymerization of microtubules in cells.Ti O₂-NPs at 10 mg/L is a safe and effective dose to use and is not bio-toxic to plants.In summary,the present study is the first to investigate the function of At AUR1 in enhancing UV-B radiation-induced"partition-bundle division"at the cellular,protein and gene levels,and provides new insights into the molecular mechanism of"partition-bundle division".The results provide a new way of thinking for the elucidation of the molecular mechanism of"partition-bundle division".In addition,the effects on plant physiological metabolism and growth and development were investigated.On the one hand,it provides some experimental basis for the application of nanomaterials in the mitigation of UV-B stress,and on the other hand,it demonstrates the risk of stress that nanomaterials may pose to plants.Therefore,nanomaterials application needs to be assessed for possible environmental risks.