Glandular trichome density and essential oil composition in leaves and inflorescences of Lippia origanoides Kunth (Verbenaceae) in the Brazilian Cerrado

Abstract

The essential oils from leaves and inflorescences of Lippia origanoides Kunth present aromatic and medicinal potential and have been used to treat several diseases, including melanoma. In Brazil, L. origanoides is commonly found in campo cerrado and cerrado stricto sensu, physiognomies featured mainly by the differential light conditions to which short and medium-sized plants are subjected. Our aim was to investigate the glandular trichome density and the yield and chemical composition of the essential oils in leaves and inflorescences of L. origanoides from campo cerrado and cerrado stricto sensu. For glandular density analysis, leaves and inflorescences were processed according to conventional techniques for scanning electron microscopy. The essential oils of leaves and inflorescences were obtained by hydrodistillation and identified with gas chromatography. Bracts and sepals showed the highest glandular density, followed by petals and leaves. The glandular density in the abaxial leaf surface was higher in individuals from the campo cerrado. In both populations the essential oil yield was higher in inflorescences than in leaves. The chemical composition of the essential oils varied among individuals from different areas and inside a same population. Our results demonstrated the chemical plasticity of L. origanoides suggesting the importance of monitoring its popular use.

Trichome Density in Relation to Volatiles Emission and 1,8‐Cineole Synthase Gene Expression in Thymus albicans Vegetative and Reproductive Organs

“…High peltate trichome density probably plays a defensive role against biotic agents and, along with non‐glandular trichomes, contributes to shelter the plant from damaging radiation and high temperatures . In fact, these plants live in dry and consolidated sandy soils under high light intensity and the dense layer of peltate trichomes may provide better protection by reflecting sunlight and thus minimizing water loss, as proposed by Tozin et al …”

“…High peltate trichome density probably plays a defensive role against biotic agents and, along with non-glandular trichomes, contributes to shelter the plant from damaging radiation and high temperatures. [22 -24] In fact, these plants live in dry and consolidated sandy soils under high light intensity and the dense layer of peltate trichomes may provide better protection by reflecting sunlight and thus minimizing water loss, as proposed by Tozin et al [25] Due to the high density of non-glandular trichomes in developed leaves and bracts, it was not possible to count accurately small capitate and digitiform tri-chomes. Of all the organs studied in T. albicans, the corolla had the lowest glandular trichome density ( Table 2).…”

Morphology and histochemistry of glandular trichomes in Hyptis villosa Pohl ex Benth. (Lamiaceae) and differential labeling of cytoskeletal elements

“…This is a remarkable feature, since the most of the researches shows higher density of glandular hairs in the abaxial leaf surface in the studied plant species (Tozin et al 2015b;Búfalo et al 2016). In H. villosa the higher density of glandular trichomes in the adaxial leaf surface could represent an important strategy for dealing with the high light intensity that strikes on the plants in the campo cerrado (Tozin et al 2015b), improving the reflection of the sunlight, minimizing the water loss and playing a chemical defense against biotic agents (Pérez-Estrada et al 2000).…”

“…The campo cerrado is one of the physiognomies of the Cerrado (Brazilian savanna), characterized by the predominance of grasses and small shrubs with sparse trees (Maroni et al 2006), where the plant individuals are subjected to high light intensity and low air relative humidity (Tozin et al 2015b).…”

Understanding the Cerrado biome, medicinal properties of a Piperaceae, and consequences of seasonal variation in Amazonian upland lakes

“…The increasing deforestation of this area has generated a well known (albeit perhaps still not well understood) negative impact on its biodiversity and there is an awareness of the necessity of studies regarding native plants including those with medicinal properties (e.g., Tozin et al 2015) and economic potentials (e.g., Dresch et al 2015). The distribution of the distinct Cerrado physiognomies is still an open question despite the fact that different approaches, such as climatic conditions and soil composition, have been invoked (e.g., Silva and Bates 2002).…”