This project aims to identify the I-3 gene and to characterise the I-3 protein. We also aim to characterise I-3 resistance by microscopic analysis and digital gene expression analysis.
The tomato I-3 gene confers resitance to Fusarium wilt caused by the fungus Fusarium oxysporum f. sp. lycopersici. I-3 has been mapped to a 50 kb region on tomato chromosome 7 containing three candidate genes encoding receptor-like kinases (Lim et al. 2008). We are using plant transformation and VIGS (virus-induced gene silencing) combined with pathogen inoculation to determine which candidate gene corresponds to I-3. Once the I-3 gene has been identified we will use GFP(green fluorescent protein) tagging and microscopic analysist to determine the subcellular location of the I-3 protein, and use interaction cloning to identify protein interactions that lead to I-3 activation. We are especially interested in learning how the Avr1 effector protein from the fungus is able to suppress activation of I-3 mediated resistance. Defence genes, signalling pathways and key regulatory genes involved in I-3 mediated resistance will be identified by using digital gene expression analysis of transcripts expressed in resistant and susceptible plants challenged with Fusarium in the same way as described for the I-7 project and will be conducted in parallel with the I-7 project.