Anatomia ecológica da folha de Eugenia glazioviana Kiaersk (Myrtaceae)

Abstract

1RESUMO -Dos mecanismos com potencial valor adaptativo em resposta ao estresse hídrico merece destaque o apresentado por Eugenia glazioviana Kiaersk cuja perda de turgescência foliar e consequente curvatura do limbo da posição horizontal para a vertical, sem a abscisão das folhas, que estão associados à redução da superfície foliar exposta à luz solar. Dessa forma, o presente trabalho teve por objetivo a caracterização histológica da folha da espécie, visando compreender melhor esse mecanismo de resposta ao estresse hídrico. Para tanto foram realizados cortes transversais e paradérmicos da lâmina foliar, bem como, cortes transversais do pecíolo, sendo estes analisados e as imagens capturadas em microscópio de luz. Os resultados permitem, entre outras coisas, afirmar que E. glazioviania possui características tipicamente xerofíticas, sendo elas: cutícula espessa em ambas as superfícies, folha hipoestomática, com muitos tricomas tectores na face abaxial, além de uma característica que pode ser exclusiva da espécie e que possivelmente justifique tal resposta, a qual relaciona-se a presença de ductos glandulares, que percorrem toda a extensão do pecíolo, em continuidade com a lâmina foliar. ECOLOGICAL ANATOMY OF Eugenia glazioviana KIAERSK LEAF (MYRTACEAE) ABSTRACT -In response to hydrous stress, the adaptive mechanisms with a potential adaptive value presented by

Ecological anatomy of Eugenia luschnathiana (O.Berg) Klotzsch ex B.D.Jacks. (Myrtaceae) leaves in the Restinga region, state of Ceara

“…As for the coating system, some similarities can be observed with studies carried out with other Eugenia L. species such as presence of thick cuticle, hypoestomatic leaf (DEFAVERI et al, 2011;MORRETES, 2009;ESPOSITO-POLESI et al, 2011;DIAS et al, 2012;SÁ et al, 2016), unicellular tectorial trichomes, presence of trichome scars (DEFAVERI et al, 2011;MORRETES, 2009;ESPOSITO-POLESI et al, 2011) and occurrence of epidermal cells of secretory structure surrounded by cells arranged in a radiated form (DEFAVERI et al, 2011;MORRETES, 2009;DIAS et al, 2012;SÁ et al, 2016).…”

“…Uniseriate epidermis was also found in other Eugenia species (ESPOSITO-POLESI et al, 2011;MORRETES, 2009;DIAS et al, 2012;SÁ et al, 2016;DEFAVERI et al, 2011). Stomata on the same level as the other epidermal cells common in E.…”

“…The spongy parenchyma shows large intercellular spaces, vascular bundles of smaller caliber and presence of druses, as it was detected for other species of the same genus MORRETES, 2009;ESPOSITO-POLESI et al, 2011). In this type of parenchyma, the shape of cells favors the absorption of carbon dioxide for photosynthesis (MENEZES et al, 2006).…”

“…Hypoestomatic leaves also appear in other Myrtaceae (CUSTÓIO et al, 2013;MORRETES, 2011;PACHECO-SILVA;DONATO, 2016;RETAMALES et al, 2014;SILVA et al, 2013). This characteristic can favor plants that live in environments with high luminosity and periods of water deficit, enabling saving water because it reduces transpiration rates (ESPOSITO-POLESI et al, 2011).…”

“…Some characteristics such as stomata can be reported as an example in ecological plasticity, since depending on the species, the quantity may be higher or lower, under conditions of high luminosity and water scarcity MORRETES, 2009;VILE et al, 2012;OLIVEIRA et al, 2016a). Other examples that undergo modifications in the aforementioned conditions are the greater thickness of the cuticle on the adaxial face and numerous trichomes on the abaxial side (ESPOSITO-POLESI et al, 2011). In relation to luminosity, it is possible to mention, among others, greater thicknesses of the leaf blade and palisade parenchyma in leaves collected in the sun, which can increase the photosynthetic potential (EVERT, 2013; AMORIM; MELO JÚNIOR, 2017).…”