Leaf anatomical features of three Theobroma species (Malvaceae s.l.) native to the Brazilian Amazon

Abstract

Theobroma species have economic importance due to their use in the cosmetic and food industries, mainly in the production of chocolate. However, the anatomy of their vegetative structures remains poorly studied. The goal of this study was to describe the anatomical features of Theobroma grandiflorum, T. speciosum and T. subincanum to contribute to the biological knowledge of these species, as well as provide support to the biotechnological studies of native fruit plants of the Amazon. Leaves at different developmental stages were collected and analyzed under light microscopy and scanning electron microscopy. Sessile and stalked stellate trichomes and digitiform glandular trichomes were observed in the expanded leaves of T. grandiflorum and T. subincanum. These species were also similar in the morphology of the midrib, the organization of the mesophyll and the presence of starch grains in the midrib pith cells. Claviform glandular trichomes and mucilage cells in the epidermis occurred only in the expanded leaves of T. speciosum. The presence of mucilage secretory trichomes in shoot apices (colleters) of all species is a new finding for the genus Theobroma. KEYWORDS: colleters, cupuassu, glandular trichomes, mucilage, stellate trichomes. Caracteres anatômicos foliares de três espécies de Theobroma (Malvaceae s.l.) nativas da Amazônia Brasileira RESUMOAs espécies de Theobroma têm importância econômica devido a sua utilização nas indústrias cosmética e alimentícia, principalmente na produção de chocolate. Entretanto, a anatomia de suas estruturas vegetativas permanece pouco conhecida. O presente estudo teve por objetivo descrever as características anatômicas de Theobroma grandiflorum, T. speciosum e T. subincanum, como contribuição ao conhecimento biológico dessas espécies, bem como, fornecer subsídios aos estudos biotecnológicos de fruteiras nativas da Amazônia. Folhas em diferentes estágios de desenvolvimento foram coletadas e analisadas sob microscopia de luz e eletrônica de varredura. Nas folhas expandidas de T. grandiflorum e T. subincanum foram observados tricomas dos tipos estrelado séssil, pedunculado e glandular digitiforme. Estas espécies também foram similares quanto à morfologia da nervura central, à organização do mesofilo e à presença de grãos de amido no parênquima medular da nervura central. Tricomas glandulares claviformes e células mucilaginosas na epiderme do limbo foliar ocorreram somente em T. speciosum. A presença de tricomas secretores de mucilagem nos ápices vegetativos (coléteres) de todas as espécies estudadas é um novo registro para o gênero Theobroma.

Variation in leaf anatomical traits from tropical to cold‐temperate forests and linkage to ecosystem functions

“…Leaf samples were progressively dehydrated in an ethanol series (50%, 70%, 85%, 95%, and 100%) and infiltrated with warm paraffin; leaf transverse sections (8–12 μm) thickness were then cut using a rotary microtome (Leica RM2255, Germany). Lignified tissues were red‐stained using Safranin and non‐lignified cell walls were blue‐stained with Fast Green to Blue stain, leaf sections were then mounted in slides and sealed with neutral glue (Garcia, Potiguara, Kikuchi, Demarco, & Aguiar‐Dias, ; Ocheltree, Nippert, & Prasad, ; Silva, Alves, & Coan, ; Sobrado, ). The slides were observed and photographed under a light microscope (Leica DM2500, Germany).…”

Micromorfología y ultraestructura de las anteras y los granos de polen en diez genotipos élite de Theobroma cacao (Malvaceae)

“…Adicionalmente, los polifenoles junto con otros compuestos son los responsables del color y sabor del chocolate (Porter et al, 1991;Counet, Ouwerx, Rosoux, & Collin, 2004;Niemenak, Rohsius, Elwers, Ndoumou, & Lieberei, 2006;Oracz, Zyzelewicz, & Nebesny, 2015;Magrone et al, 2017). Se ha registrado para Theobroma, que los polifenoles se acumulan en las vacuolas principalmente de tejidos epidérmicos y parenquimatosos (Martini, Figueira, Lenci, & Tavares, 2008;Elwers et al, 2010;Garcia et al, 2014;Alean et al, 2020) lo cual es congruente con las observaciones anatómicas realizadas en este trabajo para las anteras y filamentos de los estambres de los genotipos analizados de T. cacao.…”

Study on diversity of foliar trichomes in thirty accessions of okra (Abelmoschus esculentus (L.) Moench.)

“…Stellate trichomes a characteristic feature of the family Malvaceae (Garcia et. al., 2014) are variable in number of ray cells and their relative length and thickness.…”