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Abstract Detail



Phytochemical Section

Westley, Rebecca M. [1], Hawkins, Barbara J. [1], Constabel, C. Peter [1].

Ecological and physiological functions of poplar root condensed tannins - can they influence nutrient uptake?

Condensed tannins (CTs) are plant secondary metabolites that are widely known for their roles in phytochemical defense and soil nutrient cycling. They are widely distributed and especially abundant in trees and woody plants. To date, most chemical ecology studies on tannins have focused either on foliar chemistry and above-ground plant-environment interactions, or on their ability to slow litter decomposition within soils. However, CTs are also very abundant in woody roots; in greenhouse-grown Populus saplings, concentrations of CTs have been found to be four-fold higher in roots compared to leaves. The physiological role(s) of tannins in roots is not known, but their abundance suggests that they may have significant functions. CTs are known to bind cations, and therefore have the potential to influence nutrient uptake and interactions in plants.
This study will test the hypothesis that CTs in roots can impact nutrient uptake, by determining the localization of CTs, in parallel with the spatial distribution of nutrient fluxes in Populus roots. Histochemical analysis using 4-DMACA (4-dimethylaminocinnamaldehyde) staining in hybrid aspen (Populus tremula x alba) demonstrated that the CTs accumulate principally in the root cap and epidermal cells of younger roots. This distribution was distinct from suberin localization, which was determined using fluorescence microscopy. Microelectrode ion flux (MIFE) measurements are now being used to measure net fluxes of NH4+, NO3- and Ca2+ at discreet locations along the root; these will then be correlated with CT localization. In addition, MIFE experiments in transgenic high-CT and wild-type roots are being carried out, and will allow for a direct test of the effects of CTs on nutrient acquisition.


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1 - University of Victoria, Centre for Forest Biology, Department of Biology, 3800 Finnerty Road, Victoria, British Columbia, V8P 5C2, Canada

Keywords:
plant polyphenols
condensed tannins
Populus
root anatomy
nutrients
microscopy.

Presentation Type: Oral Paper:Papers for Sections
Session: 30
Location: Salon 13/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 10:45 AM
Number: 30011
Abstract ID:441
Candidate for Awards:CSPB President's Award for Best Student Presentation


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