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(Reference retrieved automatically from Google Scholar through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

The control of storage xyloglucan mobilization in cotyledons of Hymenaea courbaril

Full text
Author(s):
Dos Santos‚ H.P. ; Purgatto‚ E. ; Mercier‚ H. ; Buckeridge‚ M.S.
Total Authors: 4
Document type: Journal article
Source: Plant Physiology; v. 135, n. 1, p. 287-299, 2004.
Abstract

Hymenaea courbaril is a leguminous tree species from the neotropical rain forests. Its cotyledons are largely enriched with storage cell wall polysaccharide (xyloglucan). Studies of cell wall storage polymers have been focused mostly on the mechanisms of their disassembly, whereas the control of their mobilization and the relationship between their metabolism and seedling development is not well understood. Here, we show that xyloglucan mobilization is strictly controlled by the development of first leaves of the seedling, with the start of its degradation occurring after the beginning of eophyll (first leaves) expansion. During the period of storage mobilization, an increase in the levels of xyloglucan hydrolases, starch, and free sugars were observed in the cotyledons. Xyloglucan mobilization was inhibited by shoot excision, darkness, and by treatment with the auxin-transport inhibitor N-1-naphtltylphthalamic acid. Analyses of endogenous indole-3-acetic acid in the cotyledons revealed that its increase in concentration is followed by the rise in xyloglucan hydrolase activities, indicating that auxin is directly related to xyloglucan mobilization. Cotyledons detached during xyloglucan mobilization and treated with 2,4-dichlorophenoxyacetic acid showed a similar mobilization rate as in attached cotyledons. This hormonal control is probably essential for the ecophysiological performance of this species in their natural environment since it is the main factor responsible for promoting synchronism between shoot growth and reserve degradation. This is likely to increase the efficiency of carbon reserves utilization by the growing seedling in the understorey light conditions of the rain forest. (AU)

FAPESP's process: 98/05124-8 - Conservation and sustainable use of the plant biodiversity from the cerrado and Atlantic Forest: the storage of carbohydrates and their role on the adaptation and maintainance of plants in their natural environment
Grantee:Marcos Silveira Buckeridge
Support Opportunities: BIOTA-FAPESP Program - Thematic Grants