Pollen-feeding behavior of diverse insects on Geranium delavayi, a flower with large, accessible pollen grains

Research on the pharmacognostic characteristics, physicochemical properties and in vitro antioxidant potency of Rosa laxa Retz. flos

Rosa laxa Retz. is an unexplored Rosaceae plant in Xinjiang, China, and its flower is traditionally used in Kazak to treat the common cold, fever, and epileptic seizures and lessen the effects of aging. In the present study, the pharmacognostic profiles, physicochemical properties, phytochemical characteristics, and in vitro antioxidant potency of Rosa laxa Retz. flos (RLF) were presented. In the pharmacognostic evaluation of RLF, organoleptic characteristics, internal structures, and powder information were observed, and physicochemical parameters, including moisture content, ash, pH value, swelling degree, and extractives were examined. The quantitative analysis of the chemical composition of four different polar extracts of RLF showed that the aqueous part had the highest total triterpene acid, flavonoid, and polyphenol content (4.50 ± 0.04 mg/g, 50.56 ± 0.03 mg/g, and 60.20 ± 0.09 mg/g, respectively). A high-performance liquid chromatography (HPLC)-diode array detector (DAD) method was established and the contents of gallic acid, ellagic acid, astragalin, and tiliroside in RLF were determined simultaneously. In the set concentration range, the linear relationship among the four components was good (r > 0.999), the average recoveries were 97.36%-100.54%. The contents of gallic acid, ellagic acid, astragalin, and tiliroside in RLF samples were (9.46 ± 2.31) mg/g, (10.60 ±0.75) mg/g, (1.13 ± 2.50) mg/g, and (1.11 ± 2.65) mg/g, respectively. The types of its secondary metabolites were determined by fluorescence, color reaction by chemical solvent method, and ultraviolet-visible (UV-Vis) spectroscopy. The functional groups of its secondary metabolites were determined by Fourier transform infrared (FTIR) spectroscopy. Results showed that RLF contains a variety of secondary metabolic products, including flavonoids, phenolic acid, glycoside, and organic acid. TLC identification showed it contains ursolic acid, β-sitosterol, tiliroside, astragalin, isoquercitrin, kaempferol-3-O-rutinoside, gallic acid, and ellagic acid. The in vitro antioxidant activity of different polar parts of RLF was investigated by DPPH, ABTS, and reduction performance experiments. The aqueous extract had the strongest antioxidant capacity, consistent with the high content of triterpene acids, flavonoids, and polyphenolic compounds. These findings will provide critical information for the study of quality standards and medicinal value of RLF and its extracts, justify its usage in traditional medicinal systems, and encourage the use of this plant in disease prevention and treatment. Its phytochemical composition and pharmacological studies need to be explored in future. RESEARCH HIGHLIGHTS: Optical microscope and scanning electron microscope (SEM) were used to observe the morphology, and microstructure of Rosa laxa Retz. flos (RLF). The physicochemical properties, fluorescence and phytochemical composition of four different polar extracts of RLF were analyzed by UV-Vis and FTIR. Determination of total triterpenic acid, total flavonoids, and total polyphenols in four different polar extracts of RLF by UV spectrophotometry. A high-performance liquid chromatography (HPLC)-diode array detector (DAD) method was established and the contents of gallic acid, ellagic acid, astragalin, and tiliroside in RLF were determined simultaneously. TLC confirmed that RLF contains ursolic acid, β-sitosterol, tiliroside, astragalin, isoquercitrin, kaempferol 3-rutinoside, gallic acid, and ellagic acid. The in vitro antioxidant activity of RLF was studied by DPPH, ABTS, and reducing ability experiments.

High toxin concentration in pollen may deter collection by bees in butterfly-pollinated Rhododendron molle

BACKGROUNDS AND AIMS

The hypothesis that plants evolve features that protect accessible pollen from consumption by flower visitors remains poorly understood.

METHODS

To explore potential chemical defenses against pollen consumption, we examined the pollinator assemblage, foraging behaviour, visitation frequency and pollen transfer efficiency in Rhododendron molle, a highly toxic shrub containing Rhodojaponin III. Nutrient (protein and lipid) and toxic components in pollen and other tissues were measured.

KEY RESULTS

Overall in the five populations, floral visits by butterflies and bumblebees were relatively more frequent than visits by honeybees. All foraged for nectar but not pollen. Butterflies did not differ from bumblebees in the amount of pollen removed per visit, but deposited more pollen per visit. Pollination experiments indicated that R. molle was self-compatible, but both fruit and seed production were pollen limited. Our analysis indicated that the pollen was not protein-poor and had a higher concentration of the toxic compound Rhodojaponin III than petals and leaves, which compound was undetectable in nectar.

CONCLUSION

Pollen toxicity in Rhododendron flowers may discourage pollen robbers (bees) from taking the freely accessible pollen grains, while the toxin-free nectar rewards effective pollinators, promoting pollen transfer. This preliminary study supports the hypothesis that chemical defense in pollen would be likely to evolve in species without physical protection from pollinivores.

Understanding complex mirror-image flowers - a commentary on: 'The enantiostylous floral polymorphism of Barberetta aurea (Haemodoraceae) facilitates wing pollination by syrphid flies'

This article comments on:

Steven D. Johnson, Jeremy J. Midgley and Nicola Illing. The enantiostylous floral polymorphism of Barberetta aurea (Haemodoraceae) facilitates wing pollination by syrphid flies, Annals of Botany, Volume 132, Issue 6, 3 November 2023, Pages 1107–1118, https://doi.org/10.1093/aob/mcad118

Development of Flowers Buds and Mixed Buds in the Dichasial Inflorescence of Geranium koreanum Kom. (Geraniaceae)

Flower bud differentiation is of great significance for understanding plant evolution and ecological adaptability. The development of flower buds and mixed buds in the dichasial inflorescence of Geranium koreanum was described in this paper. The morphogenesis, surface structure, and organ morphology at different growth stages of G. koreanum buds were examined in detail using scanning electron microscope and stereo microscope. The development of mixed buds started from the flattened apical meristem. The stipule and leaf primordia arose first. Subsequently, the hemispherical meristem was divided into two hemispheres, forming a terminal bud and floral bud primordia, followed by lateral bud differentiation. The formation of the terminal and lateral buds of G. koreanum was sequential and their differentiation positions were also different. The floral bud primordia would develop into two flower units and four bracts. The primordia of a flower bud first formed the sepal primordia, then the stamen and petal primordia, and finally the pistil primordia. Compared to the stamen primordia, the growth of the petal primordia was slower. Finally, all organs, especially the petals and pistil, grew rapidly. When the pistil and petals exceeded the stamens and the petals changed color, the flower bud was ready to bloom.

Translational Research on Bee Pollen as a Source of Nutrients: A Scoping Review from Bench to Real World

The emphasis on healthy nutrition is gaining a forefront place in current biomedical sciences. Nutritional deficiencies and imbalances have been widely demonstrated to be involved in the genesis and development of many world-scale public health burdens, such as metabolic and cardiovascular diseases. In recent years, bee pollen is emerging as a scientifically validated candidate, which can help diminish conditions through nutritional interventions. This matrix is being extensively studied, and has proven to be a very rich and well-balanced nutrient pool. In this work, we reviewed the available evidence on the interest in bee pollen as a nutrient source. We mainly focused on bee pollen richness in nutrients and its possible roles in the main pathophysiological processes that are directly linked to nutritional imbalances. This scoping review analyzed scientific works published in the last four years, focusing on the clearest inferences and perspectives to translate cumulated experimental and preclinical evidence into clinically relevant insights. The promising uses of bee pollen for malnutrition, digestive health, metabolic disorders, and other bioactivities which could be helpful to readjust homeostasis (as it is also true in the case of anti-inflammatory or anti-oxidant needs), as well as the benefits on cardiovascular diseases, were identified. The current knowledge gaps were identified, along with the practical challenges that hinder the establishment and fructification of these uses. A complete data collection made with a major range of botanical species allows more robust clinical information.