Morpho-anatomical study of Stevia rebaudiana roots grown in vitro and in vivo

ABSTRACT Stevia rebaudiana (Bertoni) Bertoni, Asteraceae, is used as a food additive because its leaves are a source of steviol glycosides. There are examples of tissue culture based on micropropagation and phytochemical production of S. rebaudiana leaves but there are few studies on adventitious root culture of S. rebaudiana. More than 90% of the plants used in industry are harvested indiscriminately. In order to overcome this situation, the development of methodologies that employ biotechnology, such as root culture, provides suitable alternatives for the sustainable use of plants. The aim of this study was to compare morpho-anatomical transverse sections of S. rebaudiana roots grown in vitro and in vivo. The in vitro system used to maintain root cultures consisted of a gyratory shaker under dark and light conditions and a roller bottle system. Transverse sections of S. rebaudiana roots grown in vitro were structurally and morphologically different when compared to the control plant; roots artificially maintained in culture media can have their development affected by the degree of media aeration, sugar concentration, and light. GC–MS and TLC confirmed that S. rebaudiana roots grown in vitro have the ability to produce metabolites, which can be similar to those produced by wild plants.

Morfoanatomia dos órgãos vegetativos de Piper hispidum Sw. (Piperaceae) / Morphology and anatomy of the vegetative organs of Piper hispidum Sw. (Piperaceae)

O presente trabalho teve por objetivo o estudo morfoanatômico dos órgãos vegetativos de Piper hispidum, visando a estabelecer características marcantes para a sua identificação e auxiliar estudos taxonômicos e farmacobotânicos. O material vegetal fresco e fixado foi estudado segundo as técnicas usuais de corte e coloração, incluindo análise em MEV. Piper hispidum é um arbusto com caule cilíndrico, nodoso, verde claro, com folhas alternas, ovadas, de cor verde-escura na face adaxial e verde claro na abaxial. Dentre as características anatômicas importantes para sua identificação destacam-se: parênquima cortical da raiz apresentando grupos de esclereídes. Córtex caulinar com faixas descontínuas de colênquima do tipo angular e tecido vascular organizado em dois círculos descontínuos de feixes colaterais. A folha é dorsiventral, hipoestomática, com estômatos tetracíticos. Hipoderme adaxial descontínua e abaxial frouxa com número variável de camadas; tricomas tectores e glandulares ocorrem nas duas faces. Epiderme uniestratificada e idioblastos oleíferos ocorrem em todos os órgãos.

The morphology and anatomy of the vegetative organs of Piper hispidum are described, detaching remarkable strutural aspects and contributing to taxonomical and pharmacobotanical studies. The material was studied according to the usual techniques, including SEM (Scaning Eletron Microscopy). Piper hispidum is a shrub with cylindrical and green stem, which has alternate leaves. The main anatomical characteristics that can be used in its identification are: root with sclereids on cortical parenchyma, stem cortex with discontinuous strands of angular collenchyma, and vascular tissue constituted by two discontinous circles of collateral vascular bundles. The leaf is dorsiventral and hypostomatic with tetracytic stomata. The hypodermis is discontinuous in adaxial face, loose in abaxial one and presents a variable number of layers. Uniseriate epidermis and oil idioblasts occur in all organs.