Diferenciação de laticíferos articulados em plantas de Tabernaemontana catharinensis (Apocynaceae)
Carregando...
Data
2016-02-22
Autores
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Neste estudo buscamos avaliar diferentes aspectos da diferenciação de laticíferos. O crescimento intrusivo (capacidade de crescer penetrando a lamela média de células adjacentes) e a ação indutora dos laticíferos (capacidade de induzir uma célula vizinha a adquirir características de laticíferos) são mecanismos de crescimento interessantes que podem ocorrer nos laticíferos, mas que são mal compreendidos. O etileno e o ácido jasmônico são hormônios vegetais liberados durante a herbivoria e podem afetar a diferenciação de estruturas secretoras relacionadas à defesa, como laticíferos e ductos resiníferos. Utilizando métodos convencionais em microscopia eletrônica de transmissão, para caracterização da ultraestrutura celular, e imunocitoquímicos, para a detecção de componentes de parede celular, exploramos o desenvolvimento de laticíferos articulados anastomosados com crescimento intrusivo e a ação indutora dos laticíferos no embrião maduro e na planta de Tabernaemontana catharinensis A.DC. (Apocynaceae). Além disso, pulverizamos soluções de etileno 2%, ácido jasmônico 0,1% ou água deionizada em plantas (n = 33) de T. catharinensis cultivadas em condições controladas e avaliamos a influência destes reguladores vegetais sobre a diferenciação dos laticíferos nos tecidos primários e floema secundário. Ultraestruturalmente, verificamos que o processo de incorporação de células ao sistema laticífero é distinto no embrião e na planta. Entretanto, em ambos os casos, o protoplasto da célula incorporada adquire características semelhantes à de laticíferos, e a incorporação é restrita às células em contato com laticíferos. Os tratamentos imunocitoquímicos revelaram que as paredes celulares dos laticíferos e das células do meristema fundamental no embrião maduro marcaram de maneira semelhante para JIM7 e JIM5 (homogalaturonanos com grau de alta e baixa de metil-esterificação, respectivamente), LM6 ((1→5)-α-L-arabinanos) e BS400-2 (calose). Em porções indiferenciadas do ápice caulinar na planta, as paredes dos laticíferos marcaram mais intensamente para JIM5 e LM6 e exibiram fraca ou nenhuma marcação para LM5 ((1→4)-β-D-galactanos) e BS400-2 do que as células meristemáticas adjacentes. A detecção de epitopos glicanos no ápice caulinar da planta é compatível com crescimento intrusivo em laticíferos. Análises quantitativas revelaram que a diferenciação dos laticíferos originados do meristema fundamental (córtex e medula) é reduzida por etileno exógeno, enquanto o ácido jasmônico parece não influenciar a diferenciação dos laticíferos. A diferenciação dos laticíferos originados do procâmbio e do câmbio vascular parece não ser influenciada pelo etileno e ácido jasmônico exógenos. Assim, considerando as funções protetoras do látex, plantas tratadas com etileno exógeno podem ficar mais vulneráveis ao ataque de herbívoros e patógenos.
In this study, we evaluated different aspects of the laticifer differentiation. The intrusive growth (the capacity of grow penetrating the middle lamella that cements adjacent cells) and the inducing action of laticifers (the capacity of induced an adjacent cell to acquirer laticifer features) are exciting growth mechanisms that may occur in laticifers, but they are poorly understood. Ethylene and jasmonic acid are plant hormones released during the herbivory and may affect the differentiation of secretory structures related with plant defense, as laticifers and resin ducts. Using transmission electron microcopy conventional methods (for characterization of the cell ultrastructure), and immunocytochemistry (for detection of the cell wall compounds), we explored the development of the articulated anastomosing laticifers with intrusive growth and the induction action of laticifer in the mature embryo and plant of Tabernaemontana catharinensis A.DC. (Apocynaceae). Additionally, we sprayed solutions of the 2% ethephon, 0.1% jasmonic acid and deonized water in plants of T. catharinensis (n = 33) growing under controlled conditions and evaluated the influence of these plant regulators on laticifer differentiation in the primary tissues and secondary phloem. In the ultrastructure, we verified that the process of cell incorporation within the laticifer system is distinct in the embryo and plant. However, in both the cases the protoplast of the incorporated cells acquires similar features of laticifers, and the incorporation is restricted to those cells in contact with laticifers. The immunolocalization analyses revealed that walls of laticifers and ground meristem cells in the mature embryo have similar labeled for JIM7 and JIM5 (homogacturonans with high and low degree of methyl-esterification, respectively), LM6 ((1→5)-α-L-arabinans) and BS400-2 (calose). In undifferentiated portions of the plant shoot apex, the laticifer walls show more intense labeling for JIM5 and LM6 and exhibit weak or no labeling for LM5 ((1→4)-β-D-galactans) and BS400-2 than the adjacent meristematic cells. The labeling of glycan epitopes in the shoot apex of plant is compatible with intrusive growth in laticifers. Quantitative analyzes revealed that the differentiation of laticifers from ground meristem (in cortex and pith) is reduced by exogenous ethylene, while jasmonic acid appears not to influence on the laticifer differentiation. Laticifer differentiation from procambium and vascular cambium seems be not influenced by ethylene or jasmonic acid. Thus, considering the protective latex functions, we suggest that the negative effect of exogenous ethylene on laticifer differentiation in T. catharinensis would make the plants most vulnerable to attack by herbivores and pathogens.
In this study, we evaluated different aspects of the laticifer differentiation. The intrusive growth (the capacity of grow penetrating the middle lamella that cements adjacent cells) and the inducing action of laticifers (the capacity of induced an adjacent cell to acquirer laticifer features) are exciting growth mechanisms that may occur in laticifers, but they are poorly understood. Ethylene and jasmonic acid are plant hormones released during the herbivory and may affect the differentiation of secretory structures related with plant defense, as laticifers and resin ducts. Using transmission electron microcopy conventional methods (for characterization of the cell ultrastructure), and immunocytochemistry (for detection of the cell wall compounds), we explored the development of the articulated anastomosing laticifers with intrusive growth and the induction action of laticifer in the mature embryo and plant of Tabernaemontana catharinensis A.DC. (Apocynaceae). Additionally, we sprayed solutions of the 2% ethephon, 0.1% jasmonic acid and deonized water in plants of T. catharinensis (n = 33) growing under controlled conditions and evaluated the influence of these plant regulators on laticifer differentiation in the primary tissues and secondary phloem. In the ultrastructure, we verified that the process of cell incorporation within the laticifer system is distinct in the embryo and plant. However, in both the cases the protoplast of the incorporated cells acquires similar features of laticifers, and the incorporation is restricted to those cells in contact with laticifers. The immunolocalization analyses revealed that walls of laticifers and ground meristem cells in the mature embryo have similar labeled for JIM7 and JIM5 (homogacturonans with high and low degree of methyl-esterification, respectively), LM6 ((1→5)-α-L-arabinans) and BS400-2 (calose). In undifferentiated portions of the plant shoot apex, the laticifer walls show more intense labeling for JIM5 and LM6 and exhibit weak or no labeling for LM5 ((1→4)-β-D-galactans) and BS400-2 than the adjacent meristematic cells. The labeling of glycan epitopes in the shoot apex of plant is compatible with intrusive growth in laticifers. Quantitative analyzes revealed that the differentiation of laticifers from ground meristem (in cortex and pith) is reduced by exogenous ethylene, while jasmonic acid appears not to influence on the laticifer differentiation. Laticifer differentiation from procambium and vascular cambium seems be not influenced by ethylene or jasmonic acid. Thus, considering the protective latex functions, we suggest that the negative effect of exogenous ethylene on laticifer differentiation in T. catharinensis would make the plants most vulnerable to attack by herbivores and pathogens.
Descrição
Palavras-chave
Ácido jasmônico, Apocynaceae, Imunocitoquímica, Etileno, Sistema laticífero, Ultraestrutura, Apocynaceae, Ethylene, Immunocitochemistry, Jasmonic acid, Laticifer system, Ultrastructure