Stinging hair morphology and wall biomineralization across five plant families: Conserved morphology versus divergent cell wall composition

Abstract

Mineralization patterns are surprisingly diverse and involve three different biominerals deposited in different parts of individual trichomes with calcium phosphate a common component. The physical properties of different wall regions of the stinging trichomes are thus fine-tuned to optimize their function via modulation of wall thickness and differential element deposition. Similar function is apparently achieved through divergent wall compositions.

Eating barbed wire: Direct and indirect defensive roles of non‐glandular trichomes

“…However, a few recent studies have reported that these non‐glandular trichomes are also capable of bioactive compound synthesis, which can assist or enhance plant chemical defenses. Moreover, Andama et al (2020) and a few recent studies (Mustafa, Ensikat, & Weigend, 2018) demonstrated that trichomes fortified with metals make it even worse for herbivore survival, in this case with silica. We believe that more such fortified trichomes needs to be discovered to understand their role (Mustafa et al, 2018) in other plant families as well.…”

“…Moreover, Andama et al (2020) and a few recent studies (Mustafa, Ensikat, & Weigend, 2018) demonstrated that trichomes fortified with metals make it even worse for herbivore survival, in this case with silica. We believe that more such fortified trichomes needs to be discovered to understand their role (Mustafa et al, 2018) in other plant families as well. F I G U R E 2 (a) Artistic rendering of peritrophic membrane lining and insect gut.…”

Distribution, Ecology, Chemistry and Toxicology of Plant Stinging Hairs

“…Stinging hairs of the Urtica type are unicellular hairs containing a toxic fluid and associated with a group of specialized basal cells, usually forming a pedestal elevated above neighboring epidermis cells. Aside from variations in the shape of the tip, mature stinging hairs of the Urtica type are remarkably uniform and found across Urticaceae, Loasaceae, Wigandia (Namaceae), Horovitzia cnidoscoloides (Caricaceae), and Cnidoscolus (Euphorbiaceae) [1,3]. They do, however, differ dramatically in size, ranging from roughly 1 to 7 mm in length (in the illustrated examples; Figure 1).…”

“…Thus, the term "stinging hair" has been variously used in a quite broad definition, including trichomes that, due to their shape and brittleness, break off and cause mechanical damage only. For the purposes of the present review, we follow the much narrower definition of Hewson (2019) [30], which is widely used in pertinent literature such as Thurston & Lerston (1969) [1], and more recently by Fu et al (2007) [28] and Mustafa et al (2018) [3], but dividing the stinging hairs into two different types-the Urtica type and the Tragia type. Stinging hairs of the Urtica type are unicellular hairs containing a toxic fluid and associated with a group of specialized basal cells, usually forming a pedestal elevated above neighboring epidermis cells.…”

“…Reflecting a common sentiment amongst scientists, a contemporary botanist (Prof. W. Barthlott, Bonn University) complained once that research on stinging nettles is a waste of time because generations of botanists have already studied every detail. The morphology and anatomy of stinging hairs has indeed been studied widely, and there is a solid body of knowledge on their structure [1,3]. Nevertheless, we are far from having a comprehensive understanding of stinging hair morphology, function, and toxicological mechanisms, as we intend to show below.…”