Study Of Three Minor Antenna Proteins Mutants On Photosynthetic Ability For Arabidopsis

Plants have gradually evolved a set of integral mechanisms that can adapt the environment in the ever-changing natural environment.However,in recent years,as the environment has been severely damaged,the extreme weather of high light has increased significantly in the world,resulting in seriously affecting the photosynthesis of the plants.If the plants is in a high light environment for a long time,its chloroplast photosynthetic structures including the photosynthetic antenna system and the photosystem reaction center will be affected,resulting in accumulation of a large amount of reactive oxygen species in the chloroplast of the cell.At this time,many mechanisms of scavenging reactive oxygen species in plants are worked together to make the levels of the reactive oxygen in a dynamic balance to reduce the oxidative damage caused by the reactive oxygen to the plants.However,if a large amount of the reactive oxygen species can not be removed in time in the plants,it will cause a series of the damages to the plant,including an acceleration of l ipid peroxidation,a sharp rise in malondialdehyde,and a large number of cell deaths.However,it is still unclear whether three kinds of light-harvesting pigment antenna proteins of the photosystem II of the plants,including CP29,CP26 and CP24,are responsible for the oxidative damage of plants.Therefore,in this study,homozygous mutants(koCP29,koCP26,koCP24)grown in the field were compared with the wild-type to explore their special role in plants under oxidative stress and light adaptation.The results showed that the three mutants showed a decreasing trend in energy transfer efficiency(from LHCII(light-harvesting complex II)to PSII reaction center)compared with wild-type.Compared with the wild-type plants,in koCP29 and koCP24,the rate of oxygen release showed a significant downward trend.At the same time,we also found that the photosynthetic rate and the suitability of Arabidopsis thaliana of koCP26 and koCP24 in the field were affected,but not were affected in koCP29.Plants were unaffected;the reductions in the six main antioxidant enzyme activity including superoxide dismutase,peroxidase,ascorbate peroxidase,catalase,guaiacol peroxidase,glutathione reductase and reductions part of antioxidant non-enzymatic materials including dehydroascorbate and reduced glutathione were found in koCP24 compared with the wild plants.In addition,a large number of superoxide anions and hydrogen peroxide have been founded in koCP24 in the field,which have been subjected to more severe oxidative damage.BN-PAGE results showed that the LHCII assembly in the three mutants were significantly reduced,and the phosphorylation level of the three mutants was lower than that of wild Arabidopsis thaliana.The results showed that the three kinds of light-harvesting pigment antenna proteins play different roles in the light system of plants.Among them,the CP24 plays an important role in alleviating the oxidative damage to the plants caused by the natural conditions and enhancing the photoprotection of the plant itself.In this study,the photosynthetic capacity of three mutants with the wild-type in the field was established to establish the relationship between the three antenna proteins and antioxidant damage of the plants.The correlation of antioxidant mechanisms is complementary and is of great significance for the study of the plant physiology.