Thesis Title

Functional Analysis of Grapevine Transcription Factors VaERF4 and VaERF5

Author

Qiang Chen

Date of Graduation

Summer 2007

Degree

Master of Science in Plant Science (Agriculture)

Department

School of Agriculture

Committee Chair

Wenping Qiu

Keywords

grapevine, transcription factor, function, ethylene response factor, abiotic stress

Subject Categories

Fruit Science | Genomics

Abstract

Ethylene response factors (ERF) belong to a plant-specific transcription factor family, and play pivotal roles in a plant's adaptation to various types of stresses. Two ERF genes, VaERF4 and VaERF5, were isolated from grapevine Vitis aestivalis and classified into group III of the ERF family, which are presumed to be involved in a plant's responses to abiotic stresses. These two ERFs were then expressed in model tobacco (Nicotiana tabacum) plants for studying their putative functions. Phenotype and gene expression of VaERF4 and VaERF5-transgenic tobacco plants were investigated by comparing with wild type and ß-glucuronidase gene-transgenic tobacco plants. The biomass of individual VaERF5-transgenic tobacco plants was significantly reduced in comparison with other plants on agar plates supplemented with Murashige and Skoog (MS) basal salts. The salt tolerance study showed that VaERF5-transgenic tobacco plants had a significantly lower reduction in total biomass than other plants after growing on MS media supplemented with 150 mM and 300mM NaCl for 35 days. No significant difference was observed among plants in terms of resistance to the fungus Botrytis cinerea. To discover putative target genes that are subjected to transcriptional regulation by the two ERFs, quantitative real-time polymerase chain reaction was applied to determine expression levels of selected downstream genes. It was discovered that the transcript of a tobacco osmotin gene increased only in VaERF5-transgenic tobacco plants, while other genes did not exhibit significant change. These results suggested that VaERF5 may be involved in the regulation of grapevine's response to abiotic stresses. In addition, promoters of grapevine PR1 and PR5 were isolated and cloned for analyzing their interaction with VaERF4 and VaERF5.

Copyright

© Qiang Chen

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