The promoter of the nematode resistance gene Hs1 super( pro-1) activates a nematode-responsive and feeding site-specific gene expression in sugar beet (Beta vulgaris L.) and Arabidopsis thaliana

• Published in: Plant molecular biology 2003-06, Vol.52 (3), p.643-660
• Main Authors: Thurau, T, Kifle, S, Jung, C, Cai, D
• Format: Article
• Language: English
• ISSN: 0167-4412

The Hs1 super(pro-1) gene confers resistance to the beet cyst nematode Heterodera schachtii in sugar beet (Beta vulgaris L.) on the basis of a gene-for-gene relationship. RNA-gel blot analysis revealed that the transcript of Hs1 super(pro-1) was present in uninfected roots of resistant beet at low levels but increased by about fourfold one day after nematode infection. Treatments of plants with external stimuli including salicylic acid, jasmonic acid, gibberellic acid and abscisic acid as well as wounding or salt stress did not result in changes in the gene transcription, indicating de novo transcription of Hs1 super(pro-1) upon nematode infection specifically. To study transcriptional regulation of Hs1 super(pro-1) expression at the cellular level, a 3082 bp genomic fragment representing the Hs1 super(pro-1) promoter, isolated from the YAC-DNA housing the Hs1 super(pro-1) gene, was fused to the beta -glucuronidase reporter gene (1832prm1::GUS) and transformed into susceptible beet roots and Arabidopsis plants, respectively. Fluorometric and histochemical GUS assays on transgenic beet roots and Arabidopsis plants carrying the 1832prm1::GUS construct demonstrated that the Hs1 super(pro1) promoter is functional in both species and drives a nematode responsive and feeding site-specific GUS-expression. GUS activity was detected as early as at initiation of the nematode feeding sites and GUS staining was restricted to the nematode feeding sites. To delineate the regulatory domains of the Hs1 super(pro-1) promoter, fusion genes with various 5' deletions of the Hs1 super(pro-1) promoter and the GUS gene were constructed and analysed in transgenic beet roots as well. Cis elements responsible for feeding site-specific gene expression reside between -355 and +247 from the transcriptional initiation site of Hs1 super(pro-1) whereas an enhancer region necessary for higher gene expression is located between -1199 and -705 of the promoter. The Hs1 super(pro-1) promoter drives a nematode feeding site-specific GUS expression in both sugar beet and Arabidopsis suggesting a conserved mechanism of regulation of Hs1 super(pro-1) expression in these two species.