Trichomes morphology and density analysis in some "Nepeta" species of Iran

Abstract

Nepeta are widely distributed worldwide and in different parts of Iran where seventy-nine species were registered. The essential oil of these aromatic plants, which accumulates and secrets by trichomes, has been used in medicinal and industrial products. In addition, these epidermal structures can be used as taxonomic traits. We examined the morphology and density of leaves trichomes of twelve Nepeta species using the light and scanning electron microscopes. Three types of indumentum are found in these species, which composed of two main types of glandular: peltate and capitate, and nonglandular; branched and unbranched trichomes. The number of the observed hairs differed between the studied species and analyses of variant test (ANOVA) showed significant variations among some of them. CA-joined plot proved that trichomes could be used as distinguishing characteristic. Therefore, we suggested that the type of indumentum and the most abundant glandular and non-glandular trichomes have high taxonomic value in species identification within the genus.

Morphological characterization of trichomes shows enormous variation in shape, density and dimensions across the leaves of 14 Solanum species

“…The most important and well-studied among these are trichomes: unicellular or multicellular appendages (hair-like structures) originating from epidermal cells of various plant parts including leaves, stems and flowers ( Oksanen 2018 ), and developing outwards ( Werker 2000 ). Trichomes are distributed almost universally in the plant kingdom and exhibit dramatic variation in their morphology ( Seithe and Sullivan 1990 ; van Dam et al 1999 ; Adedeji et al 2007 ; Kang et al 2010 ; Nurit-Silva and Fatima Agra 2011 ; Munien et al 2015 ; Mehdi Talebi et al 2018 ) and density ( Mehdi Talebi et al 2018 ), both intra- ( van Dam et al 1999 ; Kang et al 2010 ; Munien et al 2015 ) and interspecifically ( Seithe and Sullivan 1990 ; Navarro and Oualidi 1999 ; Mannethody and Purayidathkandy 2018 ; Mehdi Talebi et al 2018 ; Yu et al 2018 ), and also among and between related and distant plant families ( Kariyat et al 2018 ; Deore 2020 ; Watts and Kariyat 2021 ). For example, Munien et al (2015) found four types of trichomes (glandular, non-glandular dendritic, non-glandular bicellular and non-glandular multicellular) in Withania somnifera (intraspecific); Yu et al (2018) found a great variation in trichome morphology, dimensions, distribution and density among seven Mentha species (interspecific); Deore (2020) identified variations in trichomes among 20 species belonging to 12 different plant families and most of the species were reported to have trichomes ranging from unicellular to multicellular, conical to elongated, smooth to grooved, thin to thick walled and with or without a flat disc at the base.…”

Bactericidal, protistocidal, nematodicidal properties and chemical composition of ethanol extract of Punica granatum peel

“…(also known as the Socotran pomegranate) are the only two members of genus Punica (Holland et al, 2009). Pomegranate a long-established fruit in folk medicine (Schubert et al, 1999;Mehdi Talebi et al, 2018), has a protective and therapeutic effect in diseases such as coronary heart disease, arthritis, Alzheimer's disease, diabetes, obesity, cancer, infertility (Frawley, 1986;Cáceres et al, 1987;Schubert et al, 1999;Saxena & Vikram, 2004;Lansky & Newman, 2007). In addition to being a religious symbol and a culinary delight, the pomegranate's bark, roots, fruit peel, aril (juice sac covering the seed; sometimes used as a collective name for juice and seed), and seeds, have been used for medicinal purposes since ancient times.…”

Leaves micromorphology, chemical profile, and bioactivity of in vitro‐propagated Nepeta cyrenaica (Lamiaceae)

“…Peltate trichomes are balloon shaped and consist of a round, four‐celled, secretory head, a short stalk, and a basal epidermal cell (Figure 2A, C, D). Although different numbers of secretory head cells of peltate trichome were found in certain Nepeta taxa, 10,42 the presence of four‐celled head was previously reported for many Nepeta taxa 8,12,13,41,43,44 . The secretory cells of the peltate trichomes of N. cyrenaica are covered with a smooth cuticle.…”

“…According to Clark et al, 9 a single expanded leaf of Nepeta racemosa carries about 3000 peltate trichomes, and a single peltate trichome accumulates about 30 ng of nepetalactone in the subcuticular space. In addition to nepetalactones, there are diverse secretion products produced by both peltate and different morphotypes of capitate trichomes in the leaf indumentum of Nepeta taxa 10–13 . Therefore, a detailed micromorphological characterisation of the plant indumentum, followed by histochemical and ultrastructural analyses of the glandular trichomes, is an essential step for further phytochemical analyses.…”