dc.contributor.author	Egert, Aurelie	en_ZA
dc.contributor.author	Keller, Felix	en_ZA
dc.contributor.author	Peters, Shaun	en_ZA
dc.date.accessioned	2014-09-17T08:20:23Z
dc.date.available	2014-09-17T08:20:23Z
dc.date.issued	2013
dc.date.updated	2014-04-05T15:22:29Z
dc.description	CITATION: Egert, A., Keller, F. & Peters, S. 2013. Abiotic stress-induced accumulation of raffinose in Arabidopsis leaves is mediated by a single raffinose synthase (RS5, At5g40390). BMC Plant Biology, 3(1):218, doi:10.1186/1471-2229-13-218.	en_ZA
dc.description	The original publication is available at http://www.biomedcentral.com/1471-2229/13/218	en_ZA
dc.description.abstract	Background: The 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. Results By 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. Conclusions Collectively 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.	en_ZA
dc.description.version	Publishers’ version	en_ZA
dc.identifier.citation	Egert, A., Keller, F. & Peters, S. 2013. Abiotic stress-induced accumulation of raffinose in Arabidopsis leaves is mediated by a single raffinose synthase (RS5, At5g40390). BMC Plant Biology, 3(1):218, doi:10.1186/1471-2229-13-218.	en_ZA
dc.identifier.issn	1471-2229 (online)
dc.identifier.other	doi:10.1186/1471-2229-13-218
dc.identifier.uri	http://hdl.handle.net/10019.1/95579
dc.language.iso	en_ZA	en_ZA
dc.publisher	BioMed Central	en_ZA
dc.rights.holder	Aurelie Egert et al.; licensee BioMed Central Ltd.	en_ZA
dc.subject	Abiotic stress	en_ZA
dc.subject	Raffinose synthase	en_ZA
dc.subject	Arabidopsis	en_ZA
dc.title	Abiotic stress-induced accumulation of raffinose in Arabidopsis leaves is mediated by a single raffinose synthase (RS5, At5g40390)	en_ZA
dc.type	Article	en_ZA

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

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