Xiaomei Shu

Date of Graduation

Summer 2009

Degree

Master of Science in Plant Science (Agriculture)

Department

College of Agriculture

Committee Chair

Wenping Qiu

Abstract

Plants mount various defense responses to protect themselves against pathogens. The plant EDS1 gene plays a critical role in salicylic acid (SA)-mediated defense responses. Powdery mildew (PM) caused by the fungus Erysiphe necator (Schw.) Burr. is one of the most destructive fungal diseases on grapevine. It was reported that SA levels and its associated genes are involved in PM resistance, and a grapevine EDS1 is responsive to both SA and PM. In this study, we characterized the promoters of grapevine EDS1-like 6 (EDL6) gene from both PM-susceptible Vitis vinifera ‘Cabernet Sauvignon' and PM-resistant Vitis aestivalis ‘Norton'. DNA fragments of 1,173 bp and 1,863 bp upstream of the translation start codon were cloned from Norton and Cabernet Sauvignon, respectively, and analyzed in silico and in vivo. Compared with the upstream of EDL6 from the published V. vinifera 'Pinot Noir' genome, eight distinct gaps and defense-associated motifs were found in the promoter regions. To test for promoter activity, the promoter fragments were linked to the GUS and GFP genes and analyzed in planta for transient expression with NPR1 and WRKY30 transcription factors in tobacco. We found that the Cabernet Sauvignon EDL6 promoter activity is enhanced by SA and with transiently expressed two transcription factors in tobacco leaves. In addition, the promoter::GFP::GUS constructs were introduced into Arabidopsis ecotype Col-0, and mutants eds1, pen2, and pen2/pad4/sag101. Both of the EDL6 promoters are functional in some of Col-0, eds1, pen2 plants. But no GUS and GFP activity was detected in transgenic triple mutant. The promoters in all transgenic plants are not responsive to SA. The results confirm the defense-related function of the grapevine EDL6 promoter.

Keywords

grapevine, powdery mildew, salicylic acid, EDL6 promoter, Nicotiana tabacum, Arabidopsis thaliana

Subject Categories

Plant Sciences

Copyright

© Xiaomei Shu

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