Dissection of Mechanisms Underlying Protection to Elevated Temperature in Potato

Crop production is highly sensitive to elevated temperatures. Further rises in ambient temperature can reduce or completely inhibit potato tuber production, with damaging consequences for both producer and consumer. Recent studies have started to address molecular mechanisms that underpin acquired thermotolerance. We describe two potential mechanisms to underpin tolerance in potato plants.

Screening of a well characterised mapping population for tolerance to elevated temperature was used to identify quantitative trait loci (QTL). A candidate gene encoding HSc70 was identified within the QTL interval and a particular allelic variant of the HSc70 gene was associated with elevated yield. Expression of this allelic variant was much higher than other alleles particularly on exposure to moderately elevated temperature. Furthermore, expression of the transgene under its native promoter in the potato cultivar Desiree resulted in enhanced HSc70 expression at elevated temperature. This was reflected in greater tolerance to heat stress as determined by improved yield under moderately elevated temperature.

In addition, we describe a novel mechanism of acquired thermotolerance in young potato plants. Acquired thermotolerance is a powerful adaptive response that has been observed in many plant species. Here we describe the temperature and light conditions that elicit acquired thermotolerance. Time course experiments were used to investigate gene expression and metabolite changes associated. We also define changes in the main cellular redox buffers associated with thermotolerance and subsequent exposure to severe heat stress. Ultimately, our results will be used to develop genetic screens for heat tolerance identification and to implement novel targeted breeding approaches.