Cloning and functional characterization of the vec1 resistance gene

• Applicants: Dr. Elke Diederichsen; Professor Dr. Petr Karlovsky
• Subject Area: Plant Breeding and Plant Pathology ; Organismic Interactions, Chemical Ecology and Microbiomes of Plant Systems
• Term: from 2012 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 219001547

• Final Report Year: 2014

Final Report Abstract

The vec1 locus of Arabidopsis thaliana ecotype Burren (Bur) mediates resistance against systemic colonization by the vascular pathogen Verticillium longisporum. Identification and cloning of the underlying gene(s) was the main goal of the funded project. A fine-mapping approach using near-isogenic lines (NILs) derived from colonization-resistant ecotype Bur and colonization-susceptible ecotype Landsberg erecta (Ler) was complemented by a candidate gene approach: The effect of vec1 on transcriptome response to V. longisporum was studied in a microarray experiment and by phytohormone analysis in NILs. A tailor-made NIL (tmNIL) was specially created for the microarray experiment to represent vec1 in a confined genomic region. The effect of V. longisporum on hypocotyl anatomy of resistant and susceptible genotypes was studied to detect potential resistance reactions microscopically. Two adjacent QTL within the vec1-locus were reproducibly mapped to intervals of 240 and 40 kb respectively. The microarray experiment revealed that vec1 determined rapid defence gene induction in response to V. longisporum at the onset of systemic colonization during flowering. A single gene within vec1 was always expressed more strongly in the tmNIL and co-localised with one of the fine-mapped QTL. It was chosen as a candidate and has been cloned. Furthermore, vec1 has been shown to control the response of ABA and JA to infection by V. longisporum. A gene coding for a cytochrome P450 protein involved in JA metabolism was found in the second QTL and also cloned. The Bur-alleles of the candidate genes have been cloned into overexpression vectors and the susceptible A. thaliana ecotype Ler has been transformed. Homozygous transformants overexpressing the candidate genes are under development. Homologues of the selected candidate genes that co-localize with known V. longisporum resistance QTL were identified in the Brassica napus genome.

Publications

• (2014): ERECTA, salicylic acid, abscisic acid and jasmonic acid modulate quantitative disease resistance of Arabidopsis thaliana to Verticillium longisporum. BMC Plant Biology 14:85
  Häffner, E., Karlovsky, P., Splivallo, R., Traczewska, A., & Diederichsen, E.