Micromorphological and phytochemical survey of Ballota acetabulosa (L.) Benth

Abstract

Within the Open Science project entitled ‘Botanic Garden, factory of molecules’, a multidisciplinary study approach was applied to Ballota acetabulosa (L.) Benth., at the Ghirardi Botanic Garden (Toscolano Maderno, BS, Italy). Micromorphological and histochemical investigations were performed on the secreting structures of the vegetative and reproductive organs under light, fuorescence and electronic microscopy. Concurrently the characterization of the volatiles spontaneously emitted from leaves and flowers were examined. Four trichome morphotypes were identified: peltate and short‐stalked, medium‐stalked and long‐stalked capitate trichomes, each with a specific distribution pattern. The histochemical analysis was confirmed using ultrastructural observations, with the peltates and long‐stalked capitates as the main sites responsible for terpene production. The head‐space characterization revealed that sesquiterpene hydrocarbons dominated both in leaves and flowers, with γ‐muurolene, β‐caryophyllene and (E)‐nerolidol as the most abundant compounds. Moreover, a comparison with literature data concerning the ecological roles of the main compounds suggested their dominant roles in defence, both at the leaf and flower level. Hence, we correlated the trichome morphotypes with the production of secondary metabolites in an attempt to link these data to their potential ecological roles. Finally, we made the obtained scientific knowledge available to visitors of the Botanic Garden through the realization of new labelling dedicated to B. acetabulosa that highlights the ‘invisible’, microscopic features of the plant.

Morphology and phytochemistry of Teucrium chamaedrys L. (Lamiaceae) cultivated at the Ghirardi Botanic Garden (Lombardy, Northern Italy)

“…This heterogeneous secretion was also highlighted in the peltates of other Lamiaceae species, e.g. Scutellaria brevibracteata (Giuliani et al, 2020c), whereas in S. altissima, S. caucasica, Lavandula dentata, and Ballota acetabulosa these trichomes turned out to be terpene producers exclusively (Giuliani et al, 2021(Giuliani et al, , 2020d(Giuliani et al, , 2020a(Giuliani et al, , 2020b. Concerning the short-stalked capitates, the muco-polysaccharidic secretion was widely documented in most of the studied members of the Lamiaceae family (Giuliani and Maleci Bini, 2008).…”

“…caucasica, and B. acetabulosa (Giuliani et al, 2021(Giuliani et al, , 2020c(Giuliani et al, , 2020d(Giuliani et al, , 2020a.…”

“…Specifically, its emission from flowers could stimulate positive feedback in honeybees as Apis cerana (Abraham et al, 2018) and A. mellifera (Giuliani et al, 2020e), as well as in non-pollinators as Vespa velutina and Bombus spp. (Giuliani et al, 2021;Zhang, 2018). In addition, the high amount of γ-muurolene (42) during the flowering stage could be related to the pollination period and to a simultaneous protective action against microorganisms, diseases, and herbivores (Fernandez et al, 2021).…”

Volatile Organic Compound Composition and Glandular Trichome Characteristics of In Vitro Propagated Clinopodium pulegium (Rochel) Bräuchler: Effect of Carbon Source

“…VOC production and emission depend on the type and ontological stage of a particular organ [1,11,[32][33][34]. In a number of Lamiaceae species, the foliar VOC profile is more complex than the floral one, as evidenced by the presence of a higher number of both total and exclusive compounds [35][36][37]. Due to the more complex VOC profile, dominated by defensive compounds, the leaves were primarily ascribed a protective action.…”

“…Furthermore, a higher sesquiterpene fraction (lower monoterpene-to-sesquiterpene ratio) was also observed in C. pulegium plants cultured in the presence of carbohydrates, especially at higher sugar concentrations, compared to control plants (Figure 2). Sesquiterpenic compounds, which are typically produced in a number of plant species for their antimicrobial and insecticidal properties, as well as their role as insect pheromones [1,37], also display various pharmacological effects and are associated with diverse health benefits [41].…”