Effects Of Barley Yellow Dwarf Virus (BYDV) On Photosynthetic Physiology,Enzyme Activity And Total Phenol Content Of Longyan No.1 Oat

In order to investigate the physiological response of oat to aphid and Barley Yellow Dwarf Virus（BYDV）,this study used Longyan No.1 oat as a test material,and inoculated oat with aphids and BYDV indoors.this experiment preliminarily determined the photosynthetic pigment content and photosynthetic gas exchange parameters of oat leaves at different times（0 d,7 d,14 d,21 d,28 d,35 d）after aphid and barley yellow dwarf virus inoculation,Changes in chlorophyll fluorescence parameters,antioxidant defense enzymes,phenylalanine ammonialyase and polyphenol oxidase activities,total phenol content,soluble sugar,soluble protein,and proline content.The main research results obtained are as follows:（1）Barley Yellow Dwarf Virus infection significantly affected photosynthetic physiology of oat.With the extension of the hazard time,the content of chlorophyll Chl a,Chl b and T-Ch1 in BYDV-infected leaves decreased significantly,which were reduced by 54.90%,63.14%and 57.40%compared with healthy leaves at 35 d after inoculation（P<0.05）.The content of Car increased,which was 55.90%higher than the control at 35 days after inoculation.Chl a/Chl b first increased and then decreased slightly.At 21 d after inoculation,Chl a/Chl b increased to the maximum value after inoculation and inoculation treatment,which were 57.37%and 32.78%higher than CK,respectively（P<0.05）;Net photosynthetic rate（P_n）,water use efficiency（WUE）in BYDV infected leaves decreased,intercellular CO₂concentration（C_i）,stomatal conductance（G_s）,and transpiration rate（T_r）increased;meanwhile,the maximum in BYDV infected leaves Fluorescence（F_m）,potential photochemical efficiency（F_V/F₀）,maximum photochemical efficiency（F_V/F_m）,photochemical quenching coefficient（qP）,PSⅡphotochemical quantum yield（Yield）,and apparent electron transport rate（ETR）Shows varying degrees of reduction;non-photochemical quenching coefficient（qN）increases.From the perspective of the changes in various indicators,Compared with the aphid treatment,the damage caused by the aphid+BYDV treatment caused more serious damage to the photosynthetic capacity of oat leaves,and its photosynthetic pigment content,photosynthetic parameters and chlorophyll fluorescence parameters changed more drastically.（2）After oat were harmed by aphids and BYDV,the leaf cell membrane system was damaged to varying degrees,causing oxidative damage to membrane lipid molecules.With the increase of damage time,the content of MDA increased,the aphid+BYDV treatment reached 1.4 times of the control（no aphids）35 days after inoculation;The activities of POD showed an upward trend,which was 14.36%higher than the control at 35 days after inoculation.The activities of SOD and CAT increased first and then decreased,reaching the maximum on the 21st and 14th days respectively,which were 8.78 and 1.73 times of the control,respectively;The activities of PPO and PAL all showed an upward trend,which were36.33%and 203%higher than the control at 35 days after inoculation.Compared with the aphid treatment,the damage caused by the aphid+BYDV treatment was greater,and the activities of malondialdehyde,antioxidant defense enzyme,phenylalanine ammonia lyase and polyphenol oxidase changed more drastically.（3）With the increase of stress time,the total phenolic content showed a significant upward trend.The aphid+BYDV treatment was significantly higher than that of the control by 38.96%after 35 days of inoculation;The content of soluble sugar first increased and then decreased.At 21 days after inoculation,the difference between the aphid+BYDV treatment and the aphid treatment was significant,and it was 41.59%higher than the control;The soluble protein content decreased.At 28 and 35 days after inoculation,the soluble protein content of the poisoning treatment was 20.40%and 15.81%lower than that of the insect treatment;14 to 21 days after inoculation,the proline content of the aphid+BYDV treatment continued to increase to a maximum,which was significantly higher than that of the aphid treatment by 27.02%.Compared with the aphid treatment,the damage caused by the aphid+BYDV treatment was greater,and the changes of total phenol and osmolytes（soluble sugar,soluble protein and proline）were more severe.In summary,after being harmed by aphids and barley yellow dwarf virus,the photosynthetic characteristics,defense enzyme system,phenolic substances and osmoregulatory substances of oat leaves undergo significant physiological and biochemical changes.