Influences of polyamines on embryogenic callus proliferation and somatic embryogenesis in Litchi chinensis
To explore the effect of exogenous polyamines(PAs)on embryogenic callus(EC)proliferation and somatic embryogenesis of litchi,the morphology,structure,endogenous PA content and related enzyme activities of EC were systematically investigated using the'Feizixiao'ECs as materials subcultured on the medium supplemented with exogenous putrescine(Put),spermidine(Spd),and spermine(Spm).The results were as follows:(1)Exogenous Put,Spd and Spm treatments significantly increased the EC proliferation rate and reduced the amount of induced somatic embryos and number of germinations.The proliferated EC cells after exogenous PA treatments were more consistent in size and stained deeply and evenly.Furthermore,multicellular proembryos in EC were reduced,and fully differentiated early cotyledon embryos could be seen.(2)All the exogenous PA treatments significantly increased the endogenous PA content in EC.Among them,Put treatment had the highest content of each endogenous PA component and total PA.When the EC proliferated on the medium containing exogenous PAs was transferred to the medium without exogenous PAs(recovery culture)for proliferating,the Put content in the EC was still significantly higher than the control,however,the endogenous Spd and Spm were significantly decreased.(3)Exogenous Put treatment significantly increased the activities of ornithine decarboxylase(ODC),arginine decarboxylase(ADC),and diamine oxidase(DAO)in EC,while exogenous Spd and Spm treatments significantly reduced the activities of ODC and ADC in EC,and exogenous Spd significantly increased the polyamine oxidase(PAO)activity.When transferred to the recovery culture medium,the ADC and DAO activities of newly proliferated EC were significantly lower than those of EC cultured with exogenous PAs,but there was no significant difference in ODC and PAO activities.In summary,the exogenous PAs can affect endogenous PAs content by regulating the activities of enzymes related to PAs metabolism,thereby affecting EC proliferation and somatic embryo induction in litchi.These results provide a basis for further study on the mechanism of PAs regulating embryogenesis,and improve litchi regeneration efficiency in vitro.
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维普
