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Giant flowers of Southern magnolia are hydrated by the xylem
Citation
Feild, TS and Chatelet, DS and Brodribb, TJ, Giant flowers of Southern magnolia are hydrated by the xylem, Plant Physiology, 150, (July) pp. 1587-1597. ISSN 0032-0889 (2009) [Refereed Article]
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Copyright Statement
Copyright © 2009 by the American Society of Plant Biologists
DOI: doi:10.1104/pp.109.136127
Abstract
Flowering depends upon long-distance transport to supply water for reproductive mechanisms to function. Previous
physiological studies suggested that flowers operated uncoupled from stem xylem transport and received water primarily
from the phloem. We demonstrate that the water balance of Southern magnolia (Magnolia grandiflora) flowers is regulated in a
manner opposite from that of previously examined flowers. We show that flowers of Southern magnolia rely upon relatively
efficient xylem hydraulic transport to support high water demand during anthesis. We measured rapid rates of perianth
transpiration ranging from twice to 100 times greater than previous studies. We found that relatively efficient xylem pathways
existed between the xylem and flower. Perianth hydraulic conductance and the amount of xylem to transpirational surface area
ratios of flowers were both approximately one-third those measured for leafy shoots. Furthermore, we observed that perianth
tissues underwent significant diurnal depressions in water status during transpiring conditions. Decreases in water potential
observed between flowers and vegetative tissues were consistent with water moving from the stem xylem into the flower
during anthesis. Xylem hydraulic coupling of flowers to the stem was supported by experiments showing that transpiring
flowers were unaffected by bark girdling. With Southern magnolia being a member of a nearly basal evolutionary lineage, our
results suggest that flower water balance represents an important functional dimension that influenced early flower evolution.
Item Details
| Item Type: | Refereed Article |
|---|---|
| Research Division: | Biological Sciences |
| Research Group: | Evolutionary Biology |
| Research Field: | Biological Adaptation |
| Objective Division: | Environment |
| Objective Group: | Flora, Fauna and Biodiversity |
| Objective Field: | Forest and Woodlands Flora, Fauna and Biodiversity |
| UTAS Author: | Brodribb, TJ (Professor Tim Brodribb) |
| ID Code: | 62059 |
| Year Published: | 2009 |
| Web of Science® Times Cited: | 23 |
| Deposited By: | Plant Science |
| Deposited On: | 2010-03-09 |
| Last Modified: | 2010-05-10 |
| Downloads: | 0 |
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