Effect of GA3 and ABA on cell ultra-structure of the secondary-bursting buds in blackcurrant(Ribes nigrum)
[Objective] Blackcurrant (Ribes nigrum L.) is a small perennial shrub with good winter hardiness,but it has the problem of secondary bud burst on their stems occurring in late summer to autumn,which causes yield reduction by 10％ to 20％.In order to elucidate the mechanism of secondary sprouting in black currant,cell ultra-structure of the secondary bursting buds in two different black currant varieties was observed and changes in response to exogenous GA3 and ABA treatments were analyzed.The study not only provides understandings of the comprehensive revelation of secondary bud sprouting but also provides artificial regulation in actual production.[Methods]Two different varieties,‘Yade’ and ‘Bajila’,in the period of secondary bud burst were taken as materials.‘ Yade’ is high yielding but highly prone to secondary burst,while ‘Bajila’ is the opposite.After harvest,30 mg·L-1 GA3 and 50 mg· L-1 ABA solutions were sprayed onto the green leaves (on August 13th,2016),plants sprayed with water were taken as the control.Foliar spray was conducted until drip-off for two consecutive days.From the first day of treatment,the bud in the middle of the branch was collected.The buds with scales removed were observed for ultra-structure under transmission electron microscopy.[Results] GA3 treatment significantly promoted secondary bud sprouting.Under GA3 treatment,the phenomenon of plasmolysis in two varieties was disappeared;plasmodesmata and endoplasmic reticulums differentiated earlier;the decomposition of starch granules was faster;the number of mitochondria was increased;the large vacuoles formed and the electronic dense materials in vacuoles degraded.On the contrary,ABA treatment inhibited the secondary sprouting.Under the treatment,the phenomenon of plasmolysis occurred and the intercellular association was limited.Endoplasmic reticulum differentiated later and its length was shorter;the decomposition of starch granules was inhibited and their number increased;mitochondria were fewer and their structure was not clear.In the bud cells of ‘Yade’,the electronic dense materials in the vacuoles decomposed completely,while in ‘Bajila’ bud,these materials maintained.[Conclusion] The occurrence of the secondary sprouting in black currant is a result of bud dormancy breaking.Exogenous GA3 treatment accelerates the release of dormancy and ABA treatment promotes dormancy maintenance.This study showed that when the cells were in the state of plasmolysis,the plasmodesmata differentiation failed to occur,and secondary bud burst would not take place;when plasmolysis disappeared,which is favorable for plasmodesmata differentiation,bud burst would occur.GA3 and ABA treatments had opposite effects on plasmolysis and plasmodesmata differentiation.Therefore,it was suggested that the plasmolysis and plasmodesmata formation were the key to the secondary bud burst in black currant.There was a close relationship between decomposition of starch granules and the number of mitochondria.GA3 treatment promoted the decomposition of the electronic dense materials in the vacuoles and also promoted the the differentiation of endoplasmic reticulum,mitochondria and other organelles.ABA treatment slowed down the decomposition of electron dense materials in the vacuoles,which might be important for the resistance of black currant to poor environmental conditions in the fall or winter.
国家科技期刊平台
NSTL
万方数据
维普
