Ultrastructure of secretory and senescence phase in colleters of Bathysa gymnocarpa and B. stipulata (Rubiaceae)

Abstract

-(ultrastructure of secretory and senescence phase in colleters of Bathysa gymnocarpa and B. stipulata (Rubiaceae)). Colleters are secretory structures formed by a parenchymatic axis with vascular bundles, bound by a layer of secretory palisade-like epidermis. some studies regarding the structure of colleters have focused on secretory cells structure, but not distinguished the secretory and senescent phases. generally, in mucilage-secreting cells such as colleters, the endoplasmic reticulum and golgi apparatus are involved in secretion production and transport. in these study, colleters structure of Bathysa gymnocarpa K. schum. and B. stipulata (Vell.) C. presl. (Rubiaceae) were determined in two phases: a secretory phase and a senescence one. samples were collected and processed by usual light and electron microscopy techniques. studied colleters are constituted by an epidermal palisade layer and a central axis formed by parenchymatic cells with rare vascular traces. during the secretory phase, epidermal cells presented a dense cytoplasm, small vacuoles, enhanced rough and smooth endoplasmic reticulum, and a golgi apparatus close to large vesicles. during the senescence phase epidermal cells presented a disorganized membrane system. no intact organelles or vesicles were observed. the outer cell wall exhibited similar layers to that observed during the secretory phase. The senescent phase is easily defined by the morphology of the colleters, but not well defined at subcellular level. our research suggests that programmed cell death starts on secretory phase. however, more evidences are needed to evaluate the phenomena.Key words -light and electron microscopy, plant cell ultrastructure, programmed cell dead, secretory structure RESUMO -(ultraestrutura da fase secretora e da senescente dos coléteres de Bathysa gymnocarpa e B. stipulata (Rubiaceae)). Coléteres são estruturas secretoras formadas por um eixo parenquimático que inclui feixes vasculares, circundado por uma camada de células epidérmicas secretoras em paliçada. Em estudos sobre a estrutura dos coléteres tem sido observada a ultraestrutura das células secretoras, mas não discriminam as fases secretora e senescente. geralmente, em células secretores de mucilagem como os coléteres, o retículo endoplasmático e o complexo de golgi estão envolvidos na produção e no transporte da secreção. neste estudo, foram determinadas duas fases baseadas na estrutura dos coléteres de Bathysa gymnocarpa K. schum. and B. stipulata (Vell.) C. presl. (Rubiaceae): a fase secretora e a fase senescente. amostras foram coletadas e processadas utilizando técnicas usuais de microscopia óptica e eletrônica. os coléteres estudados são constituídos por uma camada epidérmica em paliçada e um eixo central parenquimático com traços vasculares raros. durante a fase secretora, as células epidérmicas se apresentam com o citoplasma denso, pequenos vacúolos, retículo endoplasmático liso e rugoso evidente e complexo de golgi próximo a grandes vesículas. durante a fase senescente, as cél...

Colleters in 10 species belonging to three tribes of Rubiaceae: morphoanatomical diversity and potential as useful characters for taxonomy

“…This is consistent with previous reports (Thomas 1991;Appezzato-da-Glória and Estelita 2000;Miguel et al 2010;Coelho et al 2013).…”

“…(Klein et al 2004), Bathysa stipulata, and B. gymnocarpa (Miguel et al 2010). Certain features observed here, such as colleter length, shape and development of the basal constriction, the arrangement of parenchymatous central axis, as well as the vascularization in the central axis, were reported earlier in the Rubiaceae and reflect the diversity of these structures within the family (Robbrecht 1988;Miguel et al 2009).…”

“…The presence of vascularization in colleters of the Rubiaceae had been previously reported only in Simira glaziovii (Klein et al 2004), Bathysa stipulata, and Bathysa gymnocarpa (Miguel et al 2010). Therefore, it is possible that this anatomical feature, together with differences related to colleter type, could be used to distinguish Palicourea from Psychotria species occurring in the RFMP.…”

“…Based on their external morphology and anatomical structure, the following types of colleters have been described in this family: standard, reduced standard, dendroid, brush-like, winged, and filiform (Lersten 1974a(Lersten , 1974bPuff et al 1984;Thomas 1991;Klein et al 2004;Miguel et al 2006Miguel et al , 2009Miguel et al , 2010Barreiro and Machado 2007;Vitarelli and Santos 2009;Coelho et al 2013;Mayer et al 2013;Muravnik et al 2014). The standard type is considered the most common and is characterized by a central parenchymatous axis ensheathed by a palisade secretory epidermis (Lersten 1974a(Lersten , 1974b.…”

Comparative systematic study of colleters and stipules of Rhizophoraceae with implications for adaptation to challenging environments

“…During senescence, colleter epidermal cells and core parenchyma show a disorganized subcellular structure, filled with many vesicles, but without intact organelles, as reported by Miguel et al . (). Tannins and calcium oxalate crystals in the druse form are commonly found in core parenchyma cells and stipular tissue, but not in the outer epidermal cells.…”