Deep in the Jelly: Histochemical and Functional Aspects of Mucilage-Secreting Floral Colleters in the Orchids Elleanthus brasiliensis and E. crinipes

Autor(es)

Cassola, Fabio ^{[1, 2]} ; Pereira Nunes, Carlos Eduardo ^{[1, 3]} ; Lusa, Makeli Garibotti ^{[1, 4]} ; Garcia, Vera Lucia ^[2] ; Sampaio Mayer, Juliana Lischka ^[1]

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas, Inst Biol, Campinas, SP - Brazil

^[2] Chem Biol & Agr Pluridisciplinary Res Ctr, Dept Organ & Pharmaceut Chem, Paulinia - Brazil

^[3] Univ Stirling, Dept Biol & Environm Sci, Stirling - Scotland

^[4] Univ Fed Santa Catarina, Ctr Biol Sci, Florianopolis, SC - Brazil

• Tipo de documento: Artigo Científico
• Fonte: FRONTIERS IN PLANT SCIENCE; v. 10, APR 24 2019.
• Citações Web of Science: 0

Resumo

Colleters are trichomes or emergencies that produce a sticky exudate consisting of a mixture of mucilage, lipids, terpenes, and phenolic compounds. Colleters occur in at least 60 families of angiosperms; however, reports of them are scarce for the Orchidaceae. Elleanthus brasiliensis is distinguished by the presence of an abundant gelatinous secretion that covers almost all of its inflorescences. We aimed to describe the histology of colleters in inflorescences of E. brasiliensis and Elleanthus crinipes, and to analyze the chemical composition of their secretion to better understand the functions of these secretory structures. Due to the low frequency of colleters and lack of visible secretion in E. crinipes, histochemical tests and chemical analyses were not performed for this species. Colleters are of a brush type and their secretion has, at the same time, hydrophilic and lipophilic components. Histochemical tests further revealed the presence of pectin, mucilage, lipids, terpenes, phenolic compounds, and proteins. The GC-MS analysis confirmed the presence of gamma-sitosterol and palmitic, linoleic, and stearic acids in the secretion of E. brasiliensis. Infrared analysis indicated the possible presence of polysaccharides in the secretion. The occurrence of colleters in both species studied and in other orchids described in the literature suggests that these structures are common in the inflorescences of tropical orchids. In these environments, the hydrated polysaccharides in the secretion form a dense matrix that can act as a physical barrier, and terpenes may help to protect against herbivores and pathogenic microorganisms. This information broadens our knowledge of the morphological and chemical diversity of the secretions produced by orchid colleters. (AU)

• Processo FAPESP: 03/12595-7 - Composição florística, estrutura e funcionamento da Floresta Ombrófila Densa dos Núcleos Picinguaba e Santa Virgínia do Parque Estadual da Serra do Mar, estado de São Paulo, Brasil
• Beneficiário: Carlos Alfredo Joly
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOTA - Temático
• Processo FAPESP: 15/26479-6 - Estrutura vegetativa de Pogoniopsis schenckii (Orchidaceae: Vanilloideae) e interação desta orquídea aclorofilada com fungos micorrízicos
• Beneficiário: Juliana Lischka Sampaio Mayer
• Modalidade de apoio: Auxílio à Pesquisa - Regular