Programmed Cell Death Across the Eukaryotic Kingdoms

EU 6th Framework STREP

Research group of Jonathan Jones

PCD & necrosis in plant disease resistance




Fig.: Silencing of E3 ligases reduces hypersensitive reaction (HR)  

The Jones laboratory was one of the first to clone a plant disease resistance gene and is currently interested in mechanisms of cell death initiated during the interaction between tomato and tobacco carrying the Cf-9 resistance gene and the fungus C. fulvum expressing the Avr9 avirulence gene. The group has recently identified 4 genes required for plant PCD in this reaction using differential display and functional RNAi analyses. One encodes a NAK protein kinase, and 3 encode proteins involved in ubiquitylation (1 F-box & 2 U-box proteins). This implies that the defence response and cell death are under negative regulation, and that activation of these responses upon pathogen recognition requires that these negative regulators be degraded. Since it is unlikely that the 3 distinct E3 ligase components identified recognise the same negative regulator, this work suggests that there are at least 3 distinct negative regulators of cell death. A major goal of the Jones group is to identify these negative regulators and understand their mode of action.

Relevant References

1) Yoshioka et al. (2003) Nicotiana benthamiana gp91phox Homologs NbrbohA and NbrbohB Participate in H2O2 Accumulation and Resistance to Phytophthora infestans. Plant Cell 15, 706-18
2) Krüger et al. (2002) A tomato cysteine protease required for Cf-2-dependent disease resistance and suppression of autonecrosis Science 296, 744-7
3) Austin et al. (2002) SGT1 is an essential regulator of early R gene-mediated plant defences. Science 295 2077-80
4) Dangl & Jones (2001) Plant pathogens and integrated defence responses to infection. Nature 411, 826-33
5) Dixon et al. (2000) Genetic complexity of pathogen perception by plants: The example of Rcr3, a tomato gene required specifically by Cf-2. Proc Nat Acad Sci USA 97, 8807-13

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