Abiotic stress-induced accumulation of raffinose in Arabidopsis leaves is mediated by a single raffinose synthase RS5, At5g40390Report as inadecuate




Abiotic stress-induced accumulation of raffinose in Arabidopsis leaves is mediated by a single raffinose synthase RS5, At5g40390 - Download this document for free, or read online. Document in PDF available to download.

BMC Plant Biology

, 13:218

Plant-abiotic interactions

Abstract

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.

KeywordsAbiotic stress Arabidopsis Galactinol Raffinose Raffinose synthase Seeds Water-soluble carbohydrates AbbreviationsRSRaffinose synthase

GolGalactinol

RafRaffinose

StaStachyose

GGTGalactan:galactan galactosyl transferase

α-Galα-galactosidase

GolSGalactinol synthase

ATSIP1-ATSIP2Arabidopsis thaliana seed imbibition protein 1-2

MVMethyl viologen

DWDry weight.

Electronic supplementary materialThe online version of this article doi:10.1186-1471-2229-13-218 contains supplementary material, which is available to authorized users.

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Author: Aurélie Egert - Felix Keller - Shaun Peters

Source: https://link.springer.com/



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