Apoplastic oxidation of L-asparagine is involved in the control of the green algal endophyte Acrochaete operculata Correa and Nielsen by the red seaweed Chondrus crispus Stackhouse.

Weinberger, Florian , Pohnert, G., Berndt, M.-L., Bouarab, K., Kloareg, B. and Potin, P. (2005) Apoplastic oxidation of L-asparagine is involved in the control of the green algal endophyte Acrochaete operculata Correa and Nielsen by the red seaweed Chondrus crispus Stackhouse. Journal of Experimental Botany, 56 . pp. 1317-1326. DOI 10.1093/jxb/eri132.

[img] Text
J. Exp. Bot.-2005-Weinberger-1317-26.pdf - Published Version
Restricted to Registered users only

Download (493Kb) | Contact

Supplementary data:

Abstract

Gametophytes of the marine alga Chondrus crispus are more resistant than tetrasporophytes to infection by the filamentous endophytic alga Acrochaete operculata. It has been shown recently that carrageenan oligosaccharides from the resistant gametophytic generation of C. crispus stimulate the secretion of L-asparagine (L-Asn) by the endophyte and that the host generates hydrogen peroxide and 2-oxo-succinamic acid after contact with this amino acid. Here the response of C. crispus to L-Asn and its effect on the pathogen is investigated. Chondrus crispus released hydrogen peroxide, ammonium ions, and a carbonyl compound into the medium when exposed to L-Asn. This response was correlated with an increase in oxygen consumption. Inhibitor studies indicated the involvement of a flavoenzyme in the reaction, which was sensitive to high concentrations of the reaction product, ammonium, and to chlorpromazine, quinacrine, and cyanide, inhibitors of L-amino acid oxidase. Cell wall macerate of C. crispus also responded to L-Asn, while protoplasts were inactive. Uptake of L-Asn into the cell was not necessary for the response, suggesting that the involved L-amino acid oxidase is apoplastic. Acrochaete operculata was more sensitive to hydrogen peroxide than C. crispus and settlement of A. operculata zoospores on C. crispus was reduced by 86% in the presence of L-Asn. This reduced settlement could be prevented with catalase. Chondrus crispus thus features an apoplastic amino acid oxidase, which is involved in the control of its endophytic pathogen. The modulation of the amino acid secretion in A. operculata by carrageenan oligosaccharides is therefore a key issue in the etiology of the association.

Document Type: Article
Keywords: Acrochaete; asparagine; Chondrus; endophytism; host–pathogen interactions; L-amino acid oxidase
Research affiliation: OceanRep > GEOMAR > FB3 Marine Ecology > FB3-EOE-B Experimental Ecology - Benthic Ecology
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1093/jxb/eri132
ISSN: 0022-0957
Date Deposited: 03 Dec 2008 16:51
Last Modified: 10 Jul 2017 11:42
URI: http://oceanrep.geomar.de/id/eprint/2162

Actions (login required)

View Item View Item

Document Downloads

More statistics for this item...