Discovery of the genetic basis of partial resistance against Pyrenopeziza brassicae in oilseed rape (Brassica napus)

Light leaf spot caused by Pyrenopeziza brassicae has become the economically most damaging disease of oilseed rape (Brassica napus) in the UK. This polycyclic and largely asymptomatic disease is caused by a pathogen that has become insensitive to the most commonly used azole fungicides (Carter et al., 2014) and has broken down resistance of cultivar Cracker in Scotland. These findings demonstrate that fungicides and major gene resistance are prone to lose efficacy (Fitt et al., 2016). Thus, there is an increasing need to develop partial resistance in order to protect the crop against this adaptable pathogen. Generation of durable partial resistance will also help to protect fungicides that are still effective (Carolan et al., 2017).

The aim of this project is to understand the genetic basis of partial resistance against P. brassicae in B. napus.

Specific objectives are: 1) To map QTL for resistance against P. brassicae using a segregating population of B. napus or association mapping using a diversity panel of Brassica spp. accessions supplied by KWS; 2) to test relevant germplasm in field experiments across sites in France, England and Scotland; 3) to characterise genetically diverse inocula of P. brassicae.