尽管Boraginaceae已被归类为许多昆虫的花蜜的良好来源,对他们的花蜜和蜜腺知之甚少。因此,在目前的贡献中,我们调查了BoragoofficinalisL.(琉球或星花)的花蜜生产动态和化学,以及它与传粉者的潜在相互作用能力。花期记录花蜜分泌的峰值(每花约5.1µL),在接下来的9天内线性下降。此外,进行了TEM和SEM分析,以了解花前和花后的琉球的超微结构和生理变化。而且在其分泌阶段之后。有证据表明,花蜜可能通过质外生体途径运输,也可能通过胞吐过程运输,那是粒细胞分泌。通过监测复合多糖和钙的信号证实了这一证据,分别,通过Thiéry染色和ESI/EELS技术。在分泌阶段之后,蜜腺经历了变性,可能通过自噬事件和/或衰老诱导。此外,花蜜(Nec)和其他花卉结构(即,萼片,gynoecia,和花瓣)通过分光光度法和HPLC-DAD表征,就植物次生代谢产物而言,在开花期的早期(E-)和晚期(L-)阶段。对所有样品的植物化学物质的含量进行了量化和讨论,强调这些化合物在琉球花中的潜在生物学作用(例如,抗菌,抗氧化剂,染色效果)。令人惊讶的是,在E-Nec中登记了9种酚类物质的大量积累,关于L-Nec,表明这种现象可能是功能性的,并且能够隐藏分子(例如,防御病原体)和/或生态(例如,最后呼唤传粉者)的目的。的确,众所周知,植物代谢产物影响花蜜的适口性,鼓励专业传粉者的方法,阻止花蜜强盗,改变昆虫的行为.
Although
Boraginaceae have been classified as good sources of nectar for many insects, little is still known about their nectar and nectaries. Thus, in the present contribution, we investigated the nectar production dynamics and chemistry in Borago officinalis L. (borage or starflower), together with its potential interaction capacity with pollinators. A peak of nectar secretion (∼5.1 µL per flower) was recorded at anthesis, to decrease linearly during the following 9 days. In addition, TEM and SEM analyses were performed to understand ultrastructure and morphological changes occurring in borage nectary before and after anthesis, but also after its secretory phase. Evidence suggested that nectar was transported by the apoplastic route (mainly from parenchyma to epidermis) and then released essentially by exocytotic processes, that is a granulocrine secretion. This theory was corroborated by monitoring the signal of complex polysaccharides and calcium, respectively, via Thiéry staining and ESI/EELS technique. After the secretory phase, nectary underwent degeneration, probably through autophagic events and/or senescence induction. Furthermore, nectar (Nec) and other flower structures (i.e., sepals, gynoecia with nectaries, and petals) from borage were characterized by spectrophotometry and HPLC-DAD, in terms of plant secondary metabolites, both at early (E-) and late (L-) phase from anthesis. The content of phytochemicals was quantified and discussed for all samples, highlighting potential biological roles of these compounds in the borage flower (e.g., antimicrobial, antioxidant, staining effects). Surprisingly, a high significant accumulation of flavonoids was registered in L-Nec, with respect to E-Nec, indicating that this phenomenon might be functional and able to hide molecular (e.g., defence against pathogens) and/or ecological (e.g., last call for pollinators) purposes. Indeed, it is known that these plant metabolites influence nectar palatability, encouraging the approach of specialist pollinators, deterring nectar robbers, and altering the behaviour of insects.