Ultrastructure and development of the floral nectary from Borago officinalis L. and phytochemical changes in its secretion.

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.

Nutraceutical Content and Biological Properties of Lipophilic and Hydrophilic Fractions of the Phytocomplex from Pistacia atlantica Desf. Buds, Roots, and Fruits.

The aim of the present investigation was to obtain 12 aqueous extracts and 1 oil from Pistacia atlantica Desf. subsp. atlantica specimens. The samples differed for processed plant organs (i.e., roots, buds, and fruits), gender and geographical station of the collected trees. Total phenols, flavonoids, and condensed tannins were determined, revealing that bud extracts exhibited the highest phenolic content (386.785 ± 16.227 mg GAE/g DM), followed by fruit and root preparations. Similar results were detected for flavonoids and tannins, whose quantitation ranged from 0.014 ± 0.005 to 74.780 ± 9.724 mg CE/g DM and from 0.037 ± 0.003 to 14.793 ± 0.821 mg CE/g DM, respectively. The biochemical profile of the extracts was further characterized by HPLC-DAD, in terms of specific phenolics. This analysis identified gallic acid as a typical metabolite for ripe fruit, while hydroxytyrosol for female roots and male buds. In parallel, P. atlantica fruit oil was profiled by GC-MS analysis, which detected 37 lipophilic components, including palmitic acid (the major component, ~55%), anacardol, tetradecanol, arachidic acid, squalene, and some terpenes. The samples revealed interesting antioxidant activity, with EC50 values ranging from 0.073 ± 0.001 to 193.594 ± 28.942 mg/mL and from 0.029 ± 0.001 to 103.086 ± 20.540 mg/mL, in that order, for DPPH and reducing power assays. Concerning the total antioxidant capacity, the results ranged from 0.053 ± 0.008 to 51.648 ± 1.659 mg AAE/g DM. Finally, the antimicrobial potential of the plant extracts was estimated against 7 bacterial species and 2 fungal strains, known to be human pathogens, demonstrating a good antibiotic effect for the bud extracts. All these findings strongly suggest that P. atlantica would represent a natural reservoir for novel additives to be used in therapeutic, food, and cosmetic products.

Microparticles from dental calculus disclose paleoenvironmental and palaeoecological records.

Plants have always represented a key element in landscape delineation. Indeed, plant diversity, whose distribution is influenced by geographic/climatic variability, has affected both environmental and human ecology. The present contribution represents a multi-proxy study focused on the detection of starch, pollen and non-pollen palynomorphs in ancient dental calculus collected from pre-historical individuals buried at La Sassa and Pila archaeological sites (Central Italy). The collected record suggested the potential use of plant taxa by the people living in Central Italy during the Copper-Middle Bronze Age and expanded the body of evidence reported by previous palynological and palaeoecological studies. The application of a microscopic approach provided information about domesticated crops and/or gathered wild plants and inferred considerations on ancient environments, water sources, and past health and diseases. Moreover, the research supplied data to define the natural resources (e.g., C4-plant intake) and the social use of the space during that period. Another important aspect was the finding of plant clues referable to woody habitats, characterised by broad-leaved deciduous taxa and generally indicative of a warm-temperate climate and grassy vegetation. Other unusual records (e.g., diatoms, brachysclereids) participated in defining the prehistoric ecological framework. Thus, this work provides an overview on the potential of the human dental calculus analysis to delineate some features of the ancient plant ecology and biodiversity.