Leaf anatomy and ultrastructure of Ocimum gratissimum under different light radiation levels/Anatomia e ultraestrutura foliar de Ocimum gratissimum sob diferentes niveis de radiacao luminosa

• Published in: Ciência rural Vol. 44; no. 6; p. 1037
• Main Authors: Fernandez, Valeria Ferreira, Bezerra, Lais de Almeida, Mielke, Marcelo Schramm, Silva, Delmira da Costa, Costa, Larissa Correa do Bomfim
• Format: Journal Article
• Language: Spanish
• Published: Universidade Federal de Santa Maria 01-06-2014
• Subjects: Photosynthesis; Radiation
• ISSN: 0103-8478

Plant species are able to adjust their physiological, anatomical and ultrastructural characteristics to changes in environmental factors, such as the availability of incident light. The objective of this study was to evaluate the influence of different light radiation levels on leaf anatomy and ultrastructure in plants of Ocimum gratissimum L. (Lamiaceae). Plants were grown for 93 days in four levels photosynthetic active radiation (FAR): 20, 11, 7 and 4mol [m.sup.-2] [d.sup.-1]. The increase of light intensity resulted in increase of palisade and spongy parenchyma thickness and leaf blade. However, epidermal thickness was not changed. Regarding the ultrastructural aspects, there was an increase in the size of the chloroplasts and starch granules. However, there was an increase of the stacking of the thylakoids with reducing light intensity. Anatomical and ultrastructural changes confirm the phenotypic plasticity of this species as a function of changes in light intensity. Key-words: medicinal plant, phenotypic plasticity, Lamiaceae. Especies vegetais sao capazes de ajustar suas caracteristicas fisiologicas, anatomicas e ultraestruturais aos fatores ambientais, como, por exemplo, a disponibilidade de radiacao luminosa incidente. O objetivo deste estudo foi avaliar a influencia de diferentes niveis de radiacao luminosa na anatomia e ultraestrutura foliar de Ocimum gratissimum L. (Lamiaceae). As plantas foram cultivadas por 93 dias em quatro niveis de radiacao fotossinteticamente ativa (20, 11, 7 e 4mol [m.sup.-2] [d.sup.-1]). O incremento da intensidade de luz proporcionou aumento no espessamento dos parenquimas palicadico e esponjoso e do limbo foliar, entretanto, a espessura da epiderme nao foi alterada. Em relacao aos aspectos ultraestruturais, verificouse aumento no tamanho dos cloroplastos e graos de amido e um aumento do empilhamento dos tilacoides com a reducao da intensidade de luz. As variacoes anatomicas e ultraestruturais verificadas confirmam a plasticidade fenotipica dessa especie em funcao da intensidade de radiacao luminosa. Palavras-chave: planta medicinal, plasticidade fenotipica, Lamiaceae.