Study On The Characteristics Of Active Oxygen Metabolism And Signal Transduction In Black Currants(Ribes Nigrum L.)During Bud Secondary Burst

This experiment was carried out in the Northeast Agricultural University and National and Local Joint Engineering Research Center from 2018 to 2020.Autumn germination or secondary germination often occur in the actual production of black currants,which lead to seriously damage of tree nutrition,andthe balance of tree potential.This would affect the yield,and need to be solved.Our group have obtained preliminary results on respiratory metabolism,cell ultrastructure and phenolic metabolism of secondary germination phenomenon.In this study,we used easy to secondary germination variety‘Adelinia'and not easy to secondary germination varieties‘Heifeng'assamples.Exogenous GA₃?30 mg/L?and ABA?50 mg/L?was added to regulate the secondary bud germination artificially with water as control.Then the metabolic characteristics of reactive oxygen species?ROS?,endogenous hormones?GA₃,ABA,IAA,ZT?and Ca²⁺subcellular localization of different black currant varieties during secondary germination were studied and compared.Furthermore,the relationship between ROS metabolism and secondary germination of black currant,and the signaling molecules of secondary germination of black currant were confirmed.It not only provides scientific basis for the comprehensive disclosure of the internal causes of secondary germination of black currant,but also provides theoretical basis for the artificial control of secondary germination of black currant.This can not only guarantee the high quality and safe production of black currant,improve yield and increase benefits,but also enrich the theory of secondary germination of fruit trees.The main findings are as follows:?1?Under natural conditions,secondary germination of‘Adelinia'varieties are easy to occur,while it was not easy to occur in‘Heifeng'varieties After 30 mg/L GA₃ treatment,secondary germination were both occurred in‘Adelinia'and‘Heifeng',and the germination degree of‘Adelinia'was higher than that of‘Heifeng'.ABA treatment inhibited the secondary germination of the two cultivars,and ABA treatment had a more obvious inhibitory effect on‘Heifeng'cultivars.?2?Reactive oxygen species?ROS?may play a role in regulating secondary germination of black currants as a signaling substance.The ROS content in the secondary germination bud of both cultivar‘Adelinia'easy to be re-germinated and the cultivar‘Heifeng'not easy to be re-germinated showed an increasing trend after the exogenous treatment of 30 mg/L GA₃.The increase range of the‘Adelinia'cultivar is higher than that of the cultivar‘Heifeng',which promotes the germination.After 50 mg/L ABA treatment,the contents of reactive oxygen species?ROS?in the secondary bud of‘Adelinia'and‘Heifeng'varieties were inhibited.The content of ROS in the secondary bud of‘Heifeng'varieties was decreased,and the secondary germination of black currant was inhibited.ABA treatment had obvious inhibitory effect on the secondary germination of‘Heifeng'varieties than‘Adelinia'.?3?The changes of antioxidant enzymes and antioxidants play a key role in secondary germination.The secondary germination of black currants was regulated by antioxidant enzyme activity and antioxidant content in secondary germination buds after exogenous GA₃ and ABA treatment.Exogenous GA₃ treatment promoted the activities of superoxide dismutase?SOD?,catalase?CAT?,peroxidase?POD?and ascorbic acid peroxidase?APX?in the secondary bud of the two varieties,while ABA treatment inhibited the activities of key enzymes SOD,CAT,POD and APX.Exogenous GA₃ treatment promoted the content of glutathione?GSH?in the secondary bud,while ABA treatment inhibited the content of GSH in the secondary bud.Therefore,GA₃ treatment promoted secondary germination by promoting the activity of antioxidant enzymes and the content of antioxidant substances,while ABA treatment inhibited the activity of antioxidant enzymes and substances,and then inhibited the development of secondary germination.Glutathione reductase?GR?activity was increased significantly with the ABA treatment,compared with GA₃ treatment.This may be related to high levels of oxidized glutathione?GSSG?)content in the secondary buds.This may also be that the inhibition of GR treatment in black currants secondary germination is stronger than GA₃ treatment.?4?The GA₃ treatment had no significant effect on the content of ascorbic acid?As A?in the secondary bud of the two cultivars.However,the As A content in the bud of the cultivars not easy to germination was significantly lower than that in the buds of the cultivars easy to germinataion after ABA treatment,indicating that the higher the As A content,the easier the secondary germination of black currants.?5?Under natural conditions,the contents of GA₃ in the secondary bud of both varieties were significantly increased,and the contents of ABA,ZT and IAA in the secondary bud of the easy to secondary germination variety‘Adelinia'showed an increasing trend.The contents of ABA and IAA in the secondary bud of the not easy to secondary germination variety‘Heifeng'was decreased,while the contents of ZT was increased.Therefore,endogenous GA₃ can be considered as a key factor to promote secondary germination.Through the regulation of exogenous hormones,the GA₃treatment significantly promoted the increase of GA₃,IAA and ZT contents in the buds of the two varieties,while the ABA content significantly decreased.ABA treatment significantly increased the ABA content in buds of the two cultivars and significantly decreased the content of GA₃,IAA and ZT.The results showed that GA₃,IAA and ZT promoted the secondary germination of black currants,while ABA inhibited the secondary germination.?6?Ca²⁺acts as the second messenger system of plant cells and plays an important role in black currants growth and development and germination dormancy.Exogenous GA₃ promotes the transfer of Ca²⁺from the nucleus and cytoplasmic species to vacuoles and intercellular species,and then black currant shows a second germination state.Exogenous ABA promotes the transfer of Ca²⁺from the vacuole and intercellular species to the nucleus and cytoplasm,and then black currants appears to be dormant or not easy to germinate.