Mechanistic Analysis of Quantitative Disease Resistance in Brassicas by Associative Transcriptomics

• Applicants: Professor Bruce Fitt, Ph.D.; Professorin Barbara Ann Halkier, Ph.D.; Professor Andrzej Kononowicz, Ph.D.; Dr. Christopher J. Ridout; Professor Dr. Andreas von Tiedemann
• Subject Area: Plant Breeding and Plant Pathology ; Plant Physiology
• Term: from 2015 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 263030032

Oilseed rape (OSR, Brassica napus) is a major crop worldwide, producing edible oil, biodiesel and protein for animal feed. Diseases are a major factor limiting OSR production, and this threat is increasing due to climate change and the imminent withdrawal of agrochemicals in Europe. Improved disease control is an urgent priority, and breeders are increasingly using quantitative disease resistance (QDR) which is considered broad-spectrum and durable. This research will identify the most useful QDR genes for OSR breeding and understand the mechanisms behind this to enable predictions of their effectiveness and durability. Our consortium combines the leading expertise on the major OSR pathogens, the latest research on defence mechanisms of resistance and expertise in association genetics to identify effective QDR genes. Our industrial partner, KWS, will provide expertise on deployment of QDR in the field, and on the development of genetic marker for molecular breeding of improved OSR varieties. We will identify resistance to the most important pathogens of OSR: Sclerotinia sclerotiorum, Vertcillium spp, Leptosphaeria maculans, Alternaria brassisicola, Pyenopeziza brassicae, and the model pathogens Pseudomonas syringae and Botrytis cinerea. A panel of 196 diverse OSR cultivars will be screened for resistance against these pathogens in controlled environments, and at KWS field trial sites. Schools will contribute in a citizen science project to evaluate resistance at locations throughout Europe. In the same cultivars, we will quantify induced defence responses to conserved pathogen-associated molecular patterns (PAMPs). We will also quantify glucosinolate, phenylpropanoid and and indole metabolites that contribute to resistance mechanisms. Using association genetics, we will identify resistance gene loci against multiple pathogens and understand how this relates to metabolite production and PAMP-triggered immunity.We include studies on specific genes to test hypotheses about their contribution to resistance. We will introduce tomato receptor Ve1 into B. napus and assess its ability to mediate resistance against Verticillium wilt. Whilst glucosinolates contribute to resistance, they can reduce the quality of seed. GTR1 and GTR2 are transporters in Arabidopsis that control the allocation of glucosinolates to seeds. We will test gtr1 gtr2 mutants for microbial and herbivore susceptibility, yield and root exudation. We will create gtr1, gtr2 TILLING mutants in Brassica rapa (B. napus A genome), and measure the glucosinolate loading in leaves and seed. The work could enable development of OSR with high leaf glucosinolate for resistance, and low content for improved seed quality.This research will lead to more sustainable production of OSR, with less reliance on chemical inputs which will benefit the environment.

• DFG Programme: Research Grants
• International Connection: Denmark, Netherlands, Poland, United Kingdom
• Co-Investigators: Privatdozentin Violetta Macioszek, Ph.D.; Privatdozent Henk-jan Schoonbeek, Ph.D.
• Cooperation Partner: Professor Dr. Bart Thomma