Climate change is affecting UK agriculture, and research is needed to prepare crops for the
future. Wheat is the UK’s most important crop, and needs to be protected from losses
caused by disease.
While direct effect of the environment on pathogen spread is often reported, effect of the
environment on host defence is not. Many wheat resistance genes are temperature
sensitive and these were used as a starting point to investigate defence temperature
sensitivity in wheat starting with yellow rust resistance gene Yr36, previously shown to be
temperature-sensitive. The effect of temperature on resistance was shown to be
independent of Yr36 in breeding line UC1041, and was more likely to be due to a
previously-uncharacterised background temperature sensitivity. These results suggest that
temperature changes, rather than thresholds, might influence some disease resistance
mechanisms. Understanding this phenomenon could enable the breeding of more stable
defence in crops.
In order to gain further insight into how temperature changes influence resistance, plants
were grown under different thermoperiods and challenged with different types of
pathogens; Results showed that resistance to multiple pathogens in one cultivar Claire was
enhanced under variable temperatures, compared to constant temperatures. Taken
together, the research presented revealed that defence temperature sensitivity in plants is
much more complex than previously thought, considering that both temperature changes
and different thermoperiods can influence aspects of wheat defence.
To ascertain which research approaches will be most valuable in preparing for climate
change, the effect of the environment on take-all was also investigated. Vulnerable periods
for wheat from the threat of take-all development were identified by analysing historical
datasets, and controlled environment experiments. Results showed a relationship between
initial post-sowing temperatures and spring take-all levels in 2nd 3rd or 4th winter wheats,
depending on the location.
The work on yellow rust resistance and take-all both identify vulnerable periods for wheat
caused by the environment, be it weakening of host defence responses, or increased threat
from disease pressure. Further characterisation and understanding of vulnerable periods
will be essential to control disease outbreaks under an increasingly unstable climate
