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Recent Topics Posters

Brown, Mark Philip [1], BROWN , GREGORY K [2].

Floral Mucilage – Bromeliaceae subfamily Tillandsioideae.

Currently 30 species of bromeliads, all in subfamily Tillandsioideae (ca. 1340 spp.), are documented to produce copious amounts of a clear mucilaginous material held within the primary inflorescence bracts and/or floral bracts during late pre-anthesis, and anthesis.  In most cases the floral buds are completely submersed in this mucilage.  This is the first systematic characterization of bromeliad floral mucilage, including taxonomic distribution, chemical characterization, anatomical basis for production, and review of hypotheses concerning its functional.  Field studies for this project were conducted in Napo Province, Ecuador, and Marie Selby Botanical Gardens, Sarasota, FL; the laboratory work was conducted in WY.  Conspicuous to copious levels of flora mucilage are known in six of the nine commonly recognized Tillandsioideae genera: Mezobromelia (1 sp.), Alcantarea (2 spp.), Tillandsia (3 spp.), Werauhia (5 spp.), Vriesea (6 spp.), and Guzmania (13 spp.).  The floral mucilage has a pH of 7, and is 99% water, by weight, consisting of a carbohydrate matrix with no detectable free sugars or other potentially bioactive compounds (e.g., amino acids, secondary metabolites).  Analysis of mucilage from two different species (Mezobromelia bicolor, Tillandsia orbicularis) using gas chromatography – mass spectrometry shows that the carbohydrates are composed of both 5-member ring structures (e.g., arabinofuranosides, galactofuranosides) and 6-member ring structures (e.g., galactopyranosides, xylopyranosides).   Growth assays using 11 different bacteria and one yeast (Candida albicans), showed the mucilage to have no inhibitory influence on growth, however, moderate growth facilitation was seen for two Bacillus species.   Anatomical survey of rachis, pedicel, and receptacular tissues revealed conspicuous lysogenous mucilage canals, presumably responsible for the production of the floral mucilage.  This confirmed first, and thus far only report of mucilage canals associated with bromeliad flowers (Sajo et al., 2004).  Hypotheses addressing the functional role of bromeliad flora mucilage provided are mostly be accounted for under two categories,  1) anti-herbivore/anti-florivory, or 2) pollinator attraction/reward.  Results from this study, including field observations, are consistent with an anti-herbivore/anti-florivory role.  The mucilage, especially in cases of copious production that fully submerge floral buds and all but distal portions of open corollas, appears to have a protective role analogous to the phytotelma in nidular species from Bromeliaceae subfamily Bromelioideae (e.g., Nidularium,  Canistrum).


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1 - University of Wyoming, Botany, 1000 University Ave., Laramie, WY, 82071-3165, USA
2 - UNIVERSITY OF WYOMING, Department Of Botany, BOX 3165, LARAMIE, WY, 82071-3165, USA

Keywords:
Bromeliaceae
floral mucilage.

Presentation Type: Recent Topics Poster
Session: P
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Number: PRT046
Abstract ID:1832
Candidate for Awards:None


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