Heat stress study could protect potato yields

12th Aug 2013

 

The hot climates of Egypt, Israel and Southern Europe may have seemed like a world away to UK potato growers gathered at Balruddery Farm near Dundee on 8 August for the country’s largest potato field event but the experiences of growers there have a direct impact on the UK industry which has a large seed potato export market.

High temperature is one of the most significant uncontrollable factors affecting potato yield and in the face of climate change it is more important than ever to understand why potato yields can be so dramatically reduced by hot weather so new cultivars more resilient to higher temperatures can be developed.

Potato is the world’s third most important food crop after rice and wheat and in China alone, the world’s biggest consumer of potatoes, it is anticipated that production will need to increase by 50% to meet demand over the next 20 years. However the effects of global warming on potato production have been predicted to decrease global yields by 10%-19% in 2010-39, and by 18%-32% in the 2050s at a time when more than ever is needed to feed the world’s growing population.

That is why a new study by scientists at the James Hutton Institute, which aims to identify genetic markers for tolerance to heat stress, could be of great importance in future breeding programmes to develop new potato cultivars less susceptible to high temperatures.

The optimal yield for most commercial potato varieties is produced in average day time temperatures between 14-22˚C. Any hotter than this and yield falls sharply, for example, at 27˚C, yield in the Desiree cultivar plummets to 0% and in Spunta to ~15% of maximal. This problem is accentuated in the Tropics and sub-tropical zones where the potential for the potato crop is heavily constrained by its sensitivity to heat. As the UK exports seed to countries where temperature stress is a growing problem, yield at higher temperature is an issue of increasing magnitude to the UK potato industry. There is also a real need to mitigate the effects of rising temperatures in regions of the UK to protect national food self-sufficiency.

There is a complex array of heat stress responses that may impact on overall tuber yield and the screening of potato germplasm for heat stress tolerance carried out by the James Hutton Institute team indicates a wide variation for this trait. As heat stress tolerance is likely to be multigenic, understanding the basic physiological, biochemical and molecular responses to high temperatures can benefit breeding programmes aiming to develop heat tolerant potato varieties either by conventional targeted breeding or transgenic approaches.

Explaining the importance of the new study Dr Mark Taylor of the James Hutton Institute said: “Although studies have previously examined heat stress responses in potato and other plants using a range of technologies, these have primarily focussed on responses to heat shock or the immediate acclimatory phase following a shift to elevated temperature.

“In our study we chose to examine the impact of high temperatures following acclimation of mature tuberising plants to either typical, that is 22°C during the day and 16°C during the night, or elevated, 30°C day time and 20°C night time, temperatures.

“We have combined physiological, biochemical and molecular analyses with a detailed time series of transcript and metabolite profiles in both the leaves and tubers. This analysis informs the underlying genetic and biochemical drivers of the plant’s physiological response and provides us with potential targets for developing potato varieties that can maintain yield in hotter temperatures.”

The study has also resulted in new findings which demonstrate crosstalk between biotic and abiotic stress signalling pathways, avenues that are being pursued in a seed corn project. It has also led to new insights into the thermal signalling pathway that suppresses tuberisation, a discovery that forms the basis of a patent application. It is hoped the heat stress work will be further developed in new projects with researchers from across the UK, Europe and India.

Scientists involved in the study were available to talk about their work and its potential benefits at Potatoes in Practice, the UK’s largest potato field event which attracts hundreds of growers and industry representatives to hear about the latest research.

It is a joint event organised by the Potato Council, the James Hutton Institute, SRUC and Agrii and supported by media partner Potato Review. It is held annually at the James Hutton Institute’s Balruddery Farm on the western outskirts of Dundee.

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