Helping growers find potato varieties that are more resilient to potential heat-wave disruption is critical to the sustainability and profitability of Canada's 4.5 million tonnes per year potato production, reports Portal Potatoes.news.
Recognizing this need, Dr. Xu-Qing Li, Agriculture and Agri-Food Canada (AAFC) Research Fellow at the Fredericton Research and Development Center in New Brunswick, has been studying heat stress in potatoes for years. In 2018, he took his work to the next level by joining forces with a team of scientists from the University of New Brunswick and a number of international collaborators to study the response of 55 different potato varieties to heat stress, the first large-scale study of its kind.
In most of the varieties studied, heat stress reduced the size of the leaves, but increased the tops and height of the plants, while greatly reducing the number and weight of tubers. This study also determined which varieties were the most heat tolerant: Eramosa, Chieftain, AC Belmont and Superior.
Identifying these varieties was an important first step, but even these potatoes didn't do particularly well in the heat, so it was clear more research was needed. In 2020, Dr. Lee collaborated with AAFC colleague Dr. Benoît Bizimungu and scientists at Queen's University to carry out research that was later awarded the American Journal of Potato Research.
In their publication "Influence of early maturity on resistance to heat stress in fifty varieties of potatoesIt was emphasized that potato varieties known for their early ripening in the field grew at the same rate as later ones when they were subjected to heat stress in greenhouses, i.e. the heat actually slowed down their maturation process.
The study by Dr. Lee and colleagues sought to identify specific potato genes that could help explain why this is the case and the mechanisms that determine whether a potato variety will mature early or late.
Heat stress causes the potato to react by changing the time it takes for it to ripen, and higher temperatures actually slow down its growth.
Following this award-winning study, Dr. Lee launched and led a new research project to learn even more and dive deeper into the genomic mechanisms of the potato's response to heat stress. In 2020, he identified the genes that regulate heat-induced germination.
Potatoes grown in hot, dry summers often have a defect called "pre-harvest seedlings" or "heat seedlings" that can change the chemical composition of the tubers and reduce the overall quality and marketability of the potato.
In this study, 18 different cultivars were used to find out if heat stress conditions alone are the cause of problematic sprouts. The project confirmed that heat was indeed the culprit, and that the natural precocity or lateness of the variety in question had nothing to do with whether it sprouted under stress.
To reach this conclusion, the researchers working with Dr. Li studied the transcriptome responses of heat-stressed potatoes. Transcriptome research involves examining genes, gene interaction networks, and mRNA features of a cell to see how they behave when confronted with environmental factors or diseases, providing a very deep and detailed look at cell behavior and function.
The study found that genes associated with dormancy are downregulated in heat stressed potatoes, just as they are in post-harvest post-harvest post-harvest heat-stressed potatoes, indicating that plant hormone metabolism plays a key role in germination. This information will prove useful when it comes to genetically improving potato varieties for germination resistance under high temperature conditions.
“What we found will help farmers and processors make better decisions about how to store and process heat stressed potatoes,” says Xiu-Qing Li. “This is a challenge faced by manufacturers around the world, and it was great to be able to contribute to our understanding of the issue and provide evidence-based recommendations.” The study provided important insights into the choice of potato varieties to grow, how best to plan for the storage and use of heat stressed potatoes, and knowledge to help develop heat-tolerant varieties in the future.
As climate change threatens to bring even hotter and more erratic weather, Dr. Lee suggests further evaluation of varieties during hot summer conditions and further development of comprehensive strategies to reduce the risk of heat stress.
This research is an invaluable contribution to reducing the risk of potato production in Canada and around the world.