The nature of resistance to Neonectria ditissima in apple species

The fungal pathogen, Neonectria ditissima, is the causal agent of European canker in apple. Most modern apple varieties are susceptible and there is poor chemical control of canker of trees due to its systemic nature of the disease. It has been shown that the pathogen is often present in the plants from a young age (in the nursery) and that both the rootstock and the scion can be infected, but remain asymptomatic for long periods of time. Problems in both in-field production (tree death and yield reduction) and post-harvest losses (due to postharvest rot), call for an innovative approach to combat this disease.
– Cutting-edge genomics approaches will be used to identify natural plant-derived resistance to this important pathogen in both scion varieties and in rootstocks.
– A multi-parental population will be used to characterise resistance and a combination of targeted genome sequencing techniques and pedigree-based genotyping will be used to accurately narrow down the specific genes responsible for resistance.
– Once obtained, in proof of principle experiments, genes underpinning the resistance will be transferred into a susceptible cultivar, in order to validate the resistance in other genetic backgrounds.

 

Publications:

Antonio Gómez-Cortecero, Richard J. Harrison, and Andrew D. Armitage (2015) Draft Genome Sequence of a European Isolate of the Apple Canker Pathogen Neonectria ditissima. Genome Announcements 3.6 (2015): e01243–15.  DOI: 10.1128/genomeA.01243-15

 

Antonio Gómez-Cortecero, Robert J. Saville, Reiny W. A. Scheper, Joanna K. Bowen, Hugo Agripino De Medeiros, Jennifer Kingsnorth, Xiangming Xu and Richard J. Harrison (2016) Variation in Host and Pathogen in the Neonectria/Malus Interaction; toward an Understanding of the Genetic Basis of Resistance to European Canker. Frontiers in Plant Science, 7, 1365. DOI: 10.3389/fpls.2016.01365

 

Principal Investigator: Dr Richard Harrison

Researchers: Amanda Karlstrom, Antonio Gomez, Marzena Lipska, Feli Fernandez, Dr Charlotte Nellist

Funder: BBSRC

Duration: 5 years (2017-2022)

Partners: Worldwide Fruit, Fruition, T&G, International Nurseries Network and Plant & Food Research.

Screen Shot 2018-01-24 at 21.11.13

Life cycle of Neonectria ditissima.  The fungus produces two spore types, conidia (imperfect/asexual spores) and ascospores (sexual/perfect spores).  Both spore types enter through wounds, either natural such as bud-scale scars, leaf scars, fruit scars or artificial such as pruning wounds. Thus, inoculum and points of entry on the tree are available all year round.

Screen Shot 2018-01-24 at 21.11.23

Cut shoot artificial inoculation test.  Assessing resistance/susceptibility of apple species to Neonectria ditissima.

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