Ontogenesis, histochemistry, and seasonal and luminous environmental characterization of secretory cavities in leaves ofMyrcia splendens(Myrtaceae)

Abstract

Secretory cavities are structures that secrete compounds that protects plants against herbivory and pathogenic microorganisms. These cavities have been reported in many genera. However, there are few studies on secretory cavity ontogeny in the genus <i>Myrcia</i> (Myrtaceae) as well as the effects of luminosity and seasonality on such secretory cavities. Therefore, the objective of this is to provide new information regarding the ontogenesis, structure, histochemistry and effects of seasonality in <i>M. splendens</i>. We collected and analyzed leaves from ten M. splendens specimens exposed to sun and shade during both wet and dry seasons. Samples were subjected to standard anatomical techniques for light microscopy. <i>Myrcia splendens</i> has schizo-lysigenous ontogenesis with exudates composed of lipids, essential oils, oil-resins and alkaloids. The largest secretory cavities were found in leaves exposed to sun during the dry season. The presence of lipophilic compounds may be an important strategy to plant protection against herbivores. The seasonal variations observed in the leaf secretory cavities demonstrate the anatomical plasticity of such species to light and water availability. As total area of leaf cavities in <i>M. splendens</i> reflects the seasonal variation, this should be taken into account when aiming to produce crops meant to essential oils/alkaloids extractions.

Structural and histochemical attributes of secretory ducts and cavities in leaves of four species of Calophyllaceae J. Agardh in Amazonian savannas

“…(Myrtaceae) with seasonal variations, where mucilage and neutral polysaccharides were found in the dry season. In contrast, in the rainy season, the colleters did not secrete mucilage and neutral polysaccharides (Costa et al, 2020b). In this sense, our results indicate that metabolites of secretory cells of the ducts and cavities may be related to the need to prevent water loss, since species with these phytophysiognomies undergo long periods of drought and grow in sandy soils with low water retention (personal observation).…”

Environmental Influence on the Leaf Morphoanatomical Characteristics of Myrcia splendens (Sw.) DC. (Myrtaceae)

“…the epidermis is unistratified with markedly sinuous and anticlinal walls were similarly found in other species of Myrtaceae (Retamales & Scharaschkin, 2015) like those found in the genus Eugenia (Lemos et al, 2018;Lemos et al, 2019) and Myrciaria (Pacheco-Silva & Donato, 2016). Among the epidermal cells are found the cap cells, cellular structures that cover the subepidermal secretory cavities (Ciccarelli, Pagni, & Andreucci, 2003;Costa et al, 2020).…”

“…(Ali et al, 2009), Eugenia L. (Alves, Tresmondi, & Longui, 2008;Esposito-Polesi, Rodrigues, & Almeida, 2011;Lemos, Lucena, Bonilla, & Edson-Chaves, 2019), Metrosideros (Amada, Onoda, Ichie, & Kitayama, 2017), Myrceugenia O.Berg (Retamales & Scharaschkin, 2015), Myrcia DC. (Amorim & Melo Júnior, 2016;Lemos, Lucena, Bonilla, Edson-Chaves, & Freitas, 2020;Costa, Lucena, Bonilla, Radosavljevic, & Coutinho, 2020) and Syzygium Steud. (Zhu, Chen, Cao & Ye, 2015;Abdulrahman, Ali, Fatihah, Khandaker & Mat, 2018).…”

Neither lysigenous nor just oil: Demystifying myrtaceous secretory cavities

“…The protodermal origin of secretory cavities was reported for Myrtaceae by many authors (Chatin, 1875;von Höhnel, 1881;Carr and Carr, 1970;Brocheriou, 1976;Costa et al, 2020) and for other families (Turner, 1986), with occasional reports of ground meristem origin (Leblois, 1887). When protodermal origin takes place, the epidermal mother cell acquires a polarized organization before subsequent divisions (Brocheriou, 1976).…”

“…In contrast to this view, Martinet (1872), Chatin (1875), Briosi (1892), De Bary (1884), Niedenzu (1898), and Fohn (1935) characterized the development of glands as purely lysigenous. The schizolysigeny was described by Welch (1921), Ciccarelli et al (2003), Costa et al (2020), Ribeiro and Silva (2021), and Meer et al (2022), who recognized that the development of the intercellular cavity occurs through both cell separation and cell lysis. This historical perspective makes it clear that there is still disagreement on the specific mechanism by which cavities develop in Myrtaceae.…”