Abiotic stress-induced accumulation of raffinose in Arabidopsis leaves is mediated by a single raffinose synthase (RS5, At5g40390)

BMC Plant Biology

Research Article

Shaun Peters¹  Felix Keller²  Aurélie Egert³ 

[1]Institute for Plant Biotechnology, Department of Genetics, Faculty of AgriSciences, Stellenbosch University, 7602, Matieland, South Africa

[2]Institute of Plant Biology, Molecular Plant Physiology Division, University of Zürich, Zollikerstrasse 107, CH-8008, Zürich, Switzerland

[3]Institute of Plant Biology, Molecular Plant Physiology Division, University of Zürich, Zollikerstrasse 107, CH-8008, Zürich, Switzerland

[4]Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, CH-4056, Basel, Switzerland

关键词: Abiotic stress;    Arabidopsis;    Galactinol;    Raffinose;    Raffinose synthase;    Seeds;    Water-soluble carbohydrates;   

DOI  :  10.1186/1471-2229-13-218

 received in 2013-08-29, accepted in 2013-12-09,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundThe sucrosylgalactoside oligosaccharide raffinose (Raf, Suc-Gal1) accumulates in Arabidopsis leaves in response to a myriad of abiotic stresses. Whilst galactinol synthases (GolS), the first committed enzyme in Raf biosynthesis are well characterised in Arabidopsis, little is known of the second biosynthetic gene/enzyme raffinose synthase (RS). Conflicting reports suggest the existence of either one or six abiotic stress-inducible RSs (RS-1 to -6) occurring in Arabidopsis. Indirect evidence points to At5g40390 being responsible for low temperature-induced Raf accumulation in Arabidopsis leaves.ResultsBy heterologously expressing At5g40390 in E.coli, we demonstrate that crude extracts synthesise Raf in vitro, contrary to empty vector controls. Using two independent loss-of-function mutants for At5g40390 (rs 5–1 and 5–2), we confirm that this RS is indeed responsible for Raf accumulation during low temperature-acclimation (4°C), as previously reported. Surprisingly, leaves of mutant plants also fail to accumulate any Raf under diverse abiotic stresses including water-deficit, high salinity, heat shock, and methyl viologen-induced oxidative stress. Correlated to the lack of Raf under these abiotic stress conditions, both mutant plants lack the typical stress-induced RafS activity increase observed in the leaves of wild-type plants.ConclusionsCollectively our findings point to a single abiotic stress-induced RS isoform (RS5, At5g40390) being responsible for Raf biosynthesis in Arabidopsis leaves. However, they do not support a single RS hypothesis since the seeds of both mutant plants still contained Raf, albeit at 0.5-fold lower concentration than seeds from wild-type plants, suggesting the existence of at least one other seed-specific RS. These results also unambiguously discount the existence of six stress-inducible RS isoforms suggested by recent reports.

【 授权许可】

Unknown   
© Egert et al.; licensee BioMed Central Ltd. 2013. This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.