Exploiting Next Generation Sequencing to Investigate the Genetics of Parsnip Root Disease and Develop a Marker Assisted Breeding Strategy

Parsnips (Pastinaca sativa) are a speciality crop within the UK, covering an area of around 4100 ha and a value of £64M annually. Currently the major constraint to production is the losses associated with root canker diseases caused by fungal pathogens such as Itersonilia, Mycocentrospora and Cylindrocarpon spp. This project aims to address this problem by facilitating breeding for quantitative resistance to these major diseases. Some resistance to parsnip canker exists but is difficult to select for using traditional phenotype screening methods.

Through the development of specific pathogenicity assays and the use of molecular analysis, this project has led to a greater understanding of the epidemiology of the pathogens involved in parsnip cankers. The whole genome sequence of Itersonilia has enabled detailed phylogenetic analysis of isolates, and will assist in the development of a PCR based diagnostic assay.  In addition parsnip seedling and detached root bioassays have been developed to identify a range of resistance responses to Itersonilia, Mycocentrospora and Cylindrocarpon in parsnip parent lines.

In a root assay using 96 breeding lines and 10 parent lines, a range of resistance responses to Itersonilia and Mycocentrospora was observed amongst the different lines. A further SNP-genotyped parsnip mapping population has been screened to try and determine the QTLs conferring resistance.

The project will have a direct impact upon the industry by enabling improved sustainability of parsnip production in the UK.