University of Hertfordshire

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Light leaf spot (LLS) caused by Pyrenopeziza brassicae is the most damaging disease of oilseed rape (Brassica napus) in the UK. The disease accounts for up to £160 M yield loss annually in England, despite expenditure of £20M on fungicides,
and the severity of the disease is much greater in Scotland (Karandeni Dewage et al., 2018; Ashby, 1997). In the UK, the disease has been increasing as a national problem in recent decades rather than just being confined to Scotland and Northern England.

LLS is currently controlled by a combination of cultivar resistance, fungicide applications and cultural practices. However, resistance mechanisms of the oilseed rape plant against P. brassicae are not understood well. Furthermore, fungicide
control is problematic as the pathogen has developed insensitivity to triazole fungicides (Carter et al., 2013). Carter et al. (2014) have reported decreased azole fungicide sensi This project will benefit UK and European agriculture by decreasing risk of LLS epidemics through improved understanding of resistance against P. brassicae. 195 accessions of B. napus were screened under glasshouse conditions. In collaboration with John Innes Centre, associative transcriptomics pipeline was used to identify gene expression markers from the glasshouse data and transcript data available from York knowledgebase. GEMs identified does include cinnamate 4-hydroxylase, beta adaptin and AKIN10 SNF1 kinase homolog 10. C4H is involved in phenylpropanoid pathway and 2 calatyse trans-cinnamic acid to 4-hydroxycinnamate. Phenylpropanoid pathway and C4H are thus involved in lignin metabolism, which plays an important role in disease resistance (Chen et al., 2007). Beta adaptin is a subunit of clathrin coated vesicle and there is an increasing evidence that the vesicle trafficking is involved in the plant defence. Wu et al., (2015) showed that the subunit of clathrin heavy chain2 reduced disease resistance against powdery mildew in Arabidopsis thaliana and is involved in salicylic acid signaling. Furthermore, AKIN10 SNF1 kinase homolog 10 downregulates HMG-coA reductase in A. thaliana (Robertlee et al., 2017) which is a key enzyme in mevalonate pathway and therefore, in isoprenoid production. Under biotic and abiotic stress in plants, isoprenoids serve as antioxidant (Soto et al., 2011). It will be a novel discovery to understand the role of these candidate genes in B. napus resistance against P. brassicae. This project aims to assess the disease progression in tilling B. rapa mutants corresponding to these genes (Bra018311: Cinnamate hydroxylase, Bra019302: Beta adaptin and Bra039146: AKIN10 SNF1) to assess the involvement.

Objectives and experiments planned.
1. To remove undesired mutation by backcrossing tilling mutants with wild type R-O-18.
2. KASP analysis to confirm mutation: DNA extraction and PCR.
3. Phenotypical disease scoring after infection with P. brassicae.
4. Spore counting and pathogen DNA quantification

ID: 25464940