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Strategies to increase durability of host resistance for effective control of phoma stem canker on oilseed rape

Reference	BB/M028348/1
Principal Investigator / Supervisor	Professor Bruce Fitt
Co-Investigators / Co-Supervisors	Dr Yongju Huang
Institution	University of Hertfordshire
Department	School of Life and Medical Sciences
Funding type	Research
Value (£)	116,649
Status	Completed
Type	Research Grant
Start date	01/09/2015
End date	31/08/2018
Duration	36 months

Abstract

Summary

Phoma stem canker, caused by the fungal pathogen Leptosphaeria maculans, is a damaging disease on oilseed rape in the UK, causing annual yield losses > £100M despite use of fungicides costing £20M. With recent loss of the most effective fungicides (e.g. Punch C) through EU legislation and predicted global warming, potential yield losses will increase. Use of host resistance to control this disease is becoming ever more important. However, new sources of resistance are often rendered ineffective due to pathogen population changes. The aims of this project are to monitor the emergence of new virulent races of L. maculans and to develop new control strategies to increase durability of host resistance. To maintain effectiveness of cultivar resistance against L. maculans, this project will use molecular technology to investigate the differences between different regions in distribution of virulent races of L. maculans in populations assessed from spore samples and from crop plant samples. Results will be used to guide deployment of cultivars with suitable resistance for the region where the corresponding avirulent pathogen races are predominant. Resistance against L. maculans relies on major resistance (R) gene-mediated qualitative resistance and minor gene-mediated quantitative resistance. The fungus L. maculans has high evolutionary potential to overcome host resistance. Resistance can be rendered ineffective in 2-3 years due to L. maculans population changes from avirulent to virulent. This project will investigate the molecular events leading to virulent mutations in L. maculans by exploiting new genomic information about L. maculans. Modelling work shows that the range and severity of phoma stem canker will increase under predicted global warming. To investigate the effects of environmental factors (e.g. temperature) on operation of different R genes for resistance against L. maculans, severity of phoma stem canker on cultivars with different R genes will be assessed in field experiments in different regions (i.e. different environments) and in controlled environment experiments at different temperatures. Recent work showed that R gene-mediated resistance against L. maculans (an apoplastic pathogen) operates by recognition of pathogen effectors through receptor-like proteins (RLPs). The sequences of R genes stable at increased temperatures and the genome sequences of host Brassica napus and its related species B. rapa and B. oleracea will be used to identify candidate R genes coding for RLPs. New knowledge obtained from this project will be used to develop strategies to improve control of phoma stem canker by using effective cultivar resistance. Improved control of this disease will benefit growers by reducing yield losses. It will also address the challenge of food security. The environment will also benefit from reduced use of fungicides.

Impact Summary

The involvement of scientists, breeders, agricultural advisors and a farmer in this project will ensure that outcomes of this research are exploited directly to translate scientific outputs into practical improvements to current disease management strategies. A major beneficiary of the project will be growers. New knowledge produced from this project will not only enable better control of phoma stem canker to increase yield (by reducing yield losses from the disease) but also help to reduce cost of fungicides (by using effective host resistance and targeted fungicide application to eliminate unnecessary sprays) to improve profitability. Therefore, this project will help growers to achieve more sustainable and profitable control of phoma stem canker in oilseed rape. Another major beneficiary of the project will be plant breeders. It takes 10-15 years to produce a new cultivar with good resistance. Rapid breakdown of resistance in new cultivars is very costly to breeders. The project will investigate differences between regions in distribution of virulent races of L. maculans to guide deployment of cultivars with suitable resistance for the region where the corresponding pathogen avirulent races are predominant. This will increase the lifespan of cultivars by reducing the risk of breakdown of cultivar resistance. This project will also investigate differences between different resistance genes in response to increased temperature. This new knowledge will help breeders to develop cultivars with resistance that is both durable and temperature-resilient. Agricultural advisors will also benefit from this project by providing better disease control advice. Using the new information about differences in pathogen populations between regions and differences in effects of environmental factors on resistance, agronomists can make recommendations on use of effective host resistance. Using the new information on timing of pathogen spore release, agronomistscan make recommendations on timing of fungicide applications to improve fungicide application efficiency and avoid unnecessary fungicide sprays. Agrochemical companies will also benefit from this project because targeted fungicide application will avoid extensive use of fungicide which may lead to the development of fungicide-insensitivity. Results from this research will help agrochemical companies to maintain or increase the lifespan of fungicides. Ultimately the public and environment will benefit from reduced fungicide use through improved guidance on deployment of host resistance and targeted fungicide applications. Furthermore, improved disease control in oilseed rape crops will increase yield, which will contribute to national food security. Improved control of phoma stem canker will not only increase yield to contribute to food security, but also reduce greenhouse gas (GHG) emissions to contribute to climate change mitigation.

Committee	Research Committee A (Animal disease, health and welfare)
Research Topics	Crop Science, Microbiology, Plant Science
Research Priority	X – Research Priority information not available
Research Initiative	Innovate UK (TSB) [2011-2015]
Funding Scheme	X – not Funded via a specific Funding Scheme

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