The Arabidopsis GolS1 promotor as a potential biosensor for heat stress and fungal infection?

[摘要] ENGLISH ABSTRACT: Galactinol (Gol) has classically been considered to serve as a galactose donor during the biosynthesis of raffinose family oligosaccharides (RFOs). These sucrosyl oligosaccharides have been well characterised in their roles in carbon translocation and storage and, abiotic stress protection in plants. However, recent findings have demonstrated Gol to be an efficient free radical scavenger and it has also been suggested to act as signalling molecule during induced systemic resistance (ISR), upon pathogen infection. Collectively, these findings centres to the involvement of only a single galactinol synthase gene (GolS, synthesising Gol) in Arabidopsis (AtGolS1, At2g47180). The AtGolS1 isoform has been shown to be transcriptionally up-regulated during heat stress and Botrytis cinerea infection. Further, it is also responsive to jasmonic acid, a key component of the ISR pathway. Here we targeted the AtGolS1 promotor containing well defined heat shock transcription factor elements and a single putative jasmonate binding element, to develop a dual-functional biosensor with the ability to detect both heat stress and Botrytis cinerea infection. We created transgenic Arabidopsis lines where the reporter genes β-glucuronidase (GUS) and the green florescent protein (GFP) were under the control of the AtGolS1 promotor. Using the native AtGolS1 gene as a point of reference, we confirmed that the reporter genes were transcriptionally responsive to both heat stress and methyl jasmonate treatment in transgenic Arabidopsis. Under the same experimental conditions, both GUS assays and GFP imaging correlated with these transcriptional responses. Finally, we infected the transgenic lines with Botrytis cinerea infections to analyse reporter activity. Transcript analysis of transgenic lines clearly showed an increase in transcript abundance for both the native AtGolS1 and the reporter genes in reponse to B. cinerea infection. Similarly, reporter assays revealed a distinct difference in activity between infected and uninfected plants from 24h to 96h after Botrytis cinerea infection. These results provide sufficient proof-of-concept for the AtGolS1 promotor to be used as a dual functional biosensor for both heat stress and fungal infection.

[发布机构] Stellenbosch University