多胺对荔枝胚性愈伤组织增殖与体胚发生的影响

Influences of polyamines on embryogenic callus proliferation and somatic embryogenesis in Litchi chinensis

关键词:  荔枝, 离体再生, 组织切片, 多胺, 酶活性

Key words:  litchi(Litchi chinensis), plant regeneration, histological section, polyamines, metabolic enzymes

摘要:

为探讨外源多胺(PAs)对荔枝胚性愈伤组织(EC)增殖及体胚发生的影响机制,该研究以“妃子笑”荔枝EC为材料,采用单因素法在增殖培养基中添加腐胺(Put)、亚精胺(Spd)及精胺(Spm),分析了不同PAs处理后EC的形态、结构、内源PAs含量及相关酶指标的变化。结果表明:(1)外源Put、Spd和Spm处理均显著提高了EC增殖率,减少了体胚诱导及萌发数量。经外源PAs处理增殖的EC胚性细胞大小较一致,染色深且均匀,多细胞原胚减少,可见已经分化完全的早期子叶胚。(2)外源PAs处理均显著提高了EC中内源PAs含量,其中Put处理的EC中各类内源PAs及总PAs含量最高; 当在含外源PAs培养基上增殖的EC转入不含外源PAs的培养基上增殖时(恢复培养),EC中的Put含量仍然显著高于对照,内源Spd和Spm则显著降低。(3)外源Put处理显著提高了EC中的鸟氨酸脱羧酶(ODC)、精氨酸脱羧酶(ADC)和二胺氧化酶(DAO)活性,而外源Spd、Spm处理显著降低了EC中的ODC及ADC活性,外源Spd显著提高了多胺氧化酶(PAO)活性; 恢复培养后,EC中ADC和DAO活性比恢复培养前显著降低,ODC和PAO无显著性差异。综上认为,外源PAs可以通过调节PAs代谢相关酶活性影响内源PAs含量,进而影响荔枝EC增殖和体胚诱导。该研究结果为进一步研究PAs调节荔枝体胚发生机制及提高荔枝离体再生效率提供了基础。

Abstract:

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.