Ultrastructure and secretion of glandular trichomes in species of subtribe Cajaninae Benth (Leguminosae, Phaseoleae)

Abstract

The subtribe Cajaninae of papilionoid legumes has a pantropical distribution and comprises approximately 490 species. These species have diversified throughout dry environments where there are high temperatures and strong light. The subtribe stands out because all its representatives have vesicular glands. In addition, bulbous-based and capitate trichomes are important secretory structures present in all genera of the Cajaninae. We analyzed the ultrastructure and histochemistry of these glandular trichome types in leaflets of the three species of the subtribe. Using transmission electron microscopy and histochemical analyses, we link the glandular secretions to subcellular structures. We here report for the first time the type of exudate and ultrastructure of the glands of subtribe Cajaninae. Terpenoids and phenolics were confirmed by histochemistry tests, and we observed that the organelles responsible for biosynthesis of oils are the most representative in these glands. Each glandular trichome showed particular ultrastructural features compatible with the compounds produced. We suggest that these glandular trichomes, with their respective exudates, act in defense against herbivory and against possible damage by ultraviolet radiation.

Glandular trichomes of Robinia viscosa Vent. var. hartwigii (Koehne) Ashe (Faboideae, Fabaceae)—morphology, histochemistry and ultrastructure

“…In agreement with our observations Oosthuizen and Coetzee (1983), confirm that accumulation and release of secretion are repeatable due to the development of a new cuticle beneath the ruptured layer. Similar accumulation of secretion in the subcuticular space and its release through a cuticle perforation has been reported in other representatives of the subfamily Faboideae (Zarinkamar and Sharebian 2016;Vargas et al 2019) and in the subfamily Caesalpinioideae (Paiva and Machado 2006;Souza et al 2013).…”

“…Globose trichomes are present in representatives of the tribe Desmodieae (Freitas et al 2014). Spherical and ellipsoid trichomes (Flores et al 2019) and bulbous-based trichomes (Seixas et al 2019;Vargas et al 2019) have been described in plants from the tribe Phaseoleae, and cavitated secretory trichomes have been detected in members of the tribe Indigofereae (Marquiafável et al 2009;Pignal and De Queiroz 2019). As suggested by these authors, the morphologically diverse trichomes in the different plant taxa in the subfamily Faboideae are important taxonomic traits useful for identification and classification of different taxa at the level of species, genus, subtribe, or tribe and for investigations of phylogenetic relationships.…”

“…Glandular trichomes are characteristic for representatives of many botanical families, e.g. Asteraceae (Muravnik et al 2016;Xiao et al 2016), Cannabaceae (Mahlberg and Kim 2004), Geraniaceae (Boukhris et al 2013), Lamiaceae (Maurya et al 2019), Orobanchaceae (Konarska and Chmielewski 2020), Scrophulariaceae (Attar et al 2007), Solanaceae (Bergau et al 2016), Verbenaceae (Silva et al 2016), and Fabaceae (Barros et al 2017a;Vargas et al 2019). Glandular trichomes produce, store, or secrete mainly lipophilic substances, i.e.…”

“…Various morphotypes of glandular trichomes have been distinguished in the Fabaceae family, e.g. in the subfamilies Cercidoideae (Marinho et al 2015), Caesalpinioideae (Coutinho et al 2015Silva et al 2017), and Faboideae (Matos and Paiva 2012;Flores et al 2019;Vargas et al 2019). Representatives of the family Fabaceae often have other exogenous secretory structures, such as floral nectaries (Konarska 2020), extrafloral nectaries (Gonzalez and Marazzi 2018), and osmophores (Marinho et al 2018).…”

Histochemical assays of secretory trichomes and the structure and content of mineral nutrients in Rubus idaeus L. leaves

“…Excretion from a periplasmic space of the upper cell layers pass through the cell wall, accumulate in the subcuticular cavity, and rupture it (Muravnik et al 2019). Depending on the function, each morphotype of these glands is characterised by varied responses in the defence of plants against environmental factors (Tozin et al 2017;De Vargas et al 2019). It has been found that the characteristics of trichomes and stomata are associated with immunity of mulberry to powdery mildew and can be indicators of this type of immunity in cultivation programs (Chattopadhyay et al 2011).…”