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Title: The role of extensin protein in Arabidopsis thaliana resistance to pathogen invasion
Author: Wei, Guo
ISNI:       0000 0001 3565 3560
Awarding Body: Bangor University
Current Institution: Bangor University
Date of Award: 2008
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Extensin, a major group of the hydroxyproline-rich glycoproteins, are abundant in the plant cell wall. They are rich in hydroxyproline residues which are arranged in many pentapeptide Ser (HYP)4 repeats. Extensins are the most well studied, have been implicated in nearly all aspects of plant growth and development including pollen recognition and fertilization, cell division and differentiation, the cessation of cell elongation, in response to pathogen attack and wounding. However it still remains largely unknown in the exact roles of extensin in plant cell wall. In order to address this question, the overexpressed extensin transgenic Arabidopsis plants were used to infect with the bacterial and fungal pathogens. Pathogenesis analysis within this transgenic line showed that the formation of disease symptoms was restricted by inhibiting the colonization of ) the pathogen. Additionally, bacterial defense and signal transduction pathways involved in plant defense were not perturbed in this transgenic line containing the high level of extensin proteins. This is the first study. to convincingly demonstrate a functional linkage between extensin levels and plant resistance to bacterial pathogen invasion. The expression of the atExtJ gene was investigated by infection with virulent and avirulent bacteria pathogen, which induc~d the basal defense respo.nse and hypersensitive responses marked by activa,!ing defense related genes such as PR-l. Northern analysis on the accumulation of atExtl gene and PR-l gene showed that the expression patterns of both genes were completely .... . different, suggesting that the regulation of alExtl gene was different compared to that of PR-l gene. ..~,. RNA interference (RNAi) is the most widely used approach to identify the gene functions in plant genome. In order to reveal the function of atExtl gene, the atExt1 coding sequence in sense and antisense orientation was successfully inserted into specific RNA interference (RNAi) vector to produce the most efficient silencing construct. Transgenic Arabidopsis thaliana plants containing RNAi-atExtl were generated. '-Phenotypic analysis of the transgenic plants showed that the lower atExtJ protein levels significantly delayed the different growth stages of Arabidopsis thaliana, in particularly inhibited inflorescence emergence.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available