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Title: The plant cell wall integrity sensing mechanism
Author: Tsang, Dat
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2013
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Plant cell walls are dynamic and responsive structures rather than rigid cages. Disruption of cell wall integrity prevents cell expansion: for example, inhibition of cellulose biosynthesis with isoxaben rapidly reduces root elongation. This is not a passive consequence of mechanical failure but an active response regulated by cell wall integrity (CWI) sensing pathway. Interestingly, the plant response to pathogen-associated molecular patterns (PAMPs) like flagellin shares many similarities with the CWI pathway response; such as the production of reactive oxygen species (ROS) and lignin. While root elongation is also reduced by flagellin, microarrays show that the two treatments lead to a very different expression profile. Little is known about the mechanisms and components of the CWI pathway. Here we show that inhibiting the biosynthesis of 1-aminocyclopropane-1-carboxylic acid (ACC), the immediate precursor of the plant hormones ethylene, restores elongation in roots treated with isoxaben but exacerbates the extent of the cell wall damage. Unexpectedly, ethylene itself is not required for the process. Further experiments show that the response to flg22 in roots also requires this putative signalling pathway. Auxin appears to work downstream of ACC since inhibiting auxin activity prevents growth reduction in roots treated with ACC, isoxaben or flg22We have also identified a receptor-like kinase (SRK) which is required for growth repression in root cells that are experiencing cell wall damage. Expression of this gene is rapidly and transiently induced by isoxaben. SRK (S-locus RLK) is part of a highly expanded locus of RLKs related to self-incompatibility proteins in Brassica. However, while other genes of this family are induced by cell wall stress, only SRK mutants are insensitive to acute cell wall damage. Further characterisation of the SRK is under way to confirm its role in the CWI pathway.
Supervisor: Turner, Simon; Nuhse, Thomas Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available