Identification of a mitogen-activated protein kinase, p56, which mediates the self-incompatibility response in Papaver rhoeas L.

Tudor, Richard Lee (2010). Identification of a mitogen-activated protein kinase, p56, which mediates the self-incompatibility response in Papaver rhoeas L. University of Birmingham. Ph.D.

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Abstract

Self-incompatibility (SI) is the major mechanism used by flowering plants to prevent self-pollination and thus avoid inbreeding. It is a genetically controlled mechanism that encodes a highly specific recognition system that inhibits the growth of incompatible pollen, whereas compatible pollen from an unrelated plant of the same species is able to grow and effect fertilization. In Papaver rhoeas, inhibition of incompatible pollen is mediated by a signal transduction pathway that activates a complex network of intracellular events including Ca\(^{2+}\)-dependent phosphorylation of p26, an inorganic pyrophosphatase required for pollen tube growth, depolymerisation of the pollen actin cytoskeleton and ultimately programmed cell-death (PCD). To further understand the mechanisms involved in Papaver rhoeas SI it is important to identify and characterize components of the signalling network that mediate the SI response. Recent studies have revealed that p56, a mitogen-activated protein kinase (MAPK), is involved in activation of PCD during SI. MAPKs have been shown to be important signalling components in a range of cellular responses in eukaryotes. In Arabidopsis thaliana there are 20 MAPKs with roles including cell division, abiotic stress response, wounding response and hormone signalling. Preliminary studies suggested an MPK3-like gene might encode p56, as an anti-AtMPK3 antibody cross-reacts with a protein corresponding to p56. Experiments carried out here suggest this is not the case. Using a combination of bioinformatics and proteomics data it has been possible to identify and clone a candidate p56 gene from Papaver rhoeas pollen. The putative p56 gene has homology to AtMPK9 and is a member of the T-D-Y class of MAPKs. It has been designated PrMPK9-1. An antibody raised against recombinant PrMAPK9-1 protein is being used to confirm that this gene/protein does indeed correspond to p56.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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