花外蜜腺分泌与植物糖分运输的关系以及花外蜜腺对植株防御的贡献

As for the biological function of extrafloral nectaries (EFN), the widely accepted hypothesis, i.e., “Protection Hypothesis”, states that extrafloral nectaries were used by the plants to attract ants for an indirect defence. However, some studies suggested that some herbivores could be attracted by extrafloral nectar too. Recently, studies that consider the effect of EFN on plant carbon transportation are rare. According to recent research results, we suppose that EFN may play a role in plant carbon transportation. It may help in decreasing the concentration of the phloem sap during peak hour, then decreasing the viscosity of phloem sap, ensuring transportation efficiency. In this study, by investigating the relationship between extrafloral nectar secretion and sap concentration in the vicinity, and the transportation pattern of phloem sap between EFN plants and some plants without EFN, possible effect of EFN in phloem sap flow are enquired. Through artificial nectar accumulation, further secretion of the EFN is suppressed. By comparing the growth between EFN suppressed plants and control plants, we try to study the effect of EFN secretion on plant physiological health. This study will improve our understanding on the role of extrafloral nectaries in plants' growth.

关于植物花外蜜腺的功能，“保护假说”认为, 植物通过花外蜜腺提供糖分吸引蚂蚁等捕食者的拜访来减少草食昆虫危害。然而,另外一些研究发现花外蜜腺也吸引了一些无关昆虫，甚至植食害虫。目前，从花外蜜腺与植物糖分运输的关系出发，考虑花外蜜腺在植物糖分运输中的作用的研究还很少。根据已有的研究结果结合现有的实验数据，我们推测，花外蜜腺可能在降低韧皮部光合产物运输高峰时期树液的粘度，维持糖分的高效运输中具有一定的作用。本研究选择版纳地区自然分布的花外蜜腺植物及相似功能群的无花外蜜腺植物为材料, 通过研究植株糖分运输与花外蜜腺分泌的关系，以及花外蜜腺分泌在受到抑制后对植株生长产生的影响，来了解植物花外蜜腺在其功能实现过程中更多可能的途径。该研究对更全面地了解植物花外蜜腺功能具有重要的理论意义。