Scientists at The James Hutton Institute, Scotland have made a significant breakthrough in understanding how potato tubers develop, potentially paving the way for growing potatoes in warmer climates and boosting global food security. Their research, conducted as part of a European consortium, has identified a key factor regulating the process known as potato tuber initiation.
The journey of a potato tuber begins when signals are sent from the plant’s leaves to underground stems called stolons. These signals trigger a crucial transition, stopping the stolons from extending and starting their development into tubers. The developing tuber then becomes a vital storage location for starch, which is produced from sugars made in the leaves through photosynthesis. These sugars are transported through specialised vessels called the phloem to the roots and tubers.
For the transition from stolon growth to tuber development to occur, there needs to be a substantial increase in the availability of these sugars. Around 25 years ago, scientists at the Hutton demonstrated that this critical transition was linked to a change in how sugars were unloaded from the phloem into the developing tuber. However, the specific mechanism driving this shift remained unknown until now.
Dr Rob Hancock, Deputy Director of the Hutton’s Advanced Plant Growth Centre and a member of the original team that identified the sugar unloading switch 25 years ago, led the recent research. The team’s work identified a potential candidate that orchestrates this shift: a member of the germin family of proteins.
Their research showed that a specific gene belonging to this family was directly activated by the protein complex that regulates the switch from stolon growth to tuber development. The role of germins in tuberisation was unexpected, as they are a large class of proteins with functions that are not well understood.
To investigate further, the scientists artificially manipulated the activity of the germin3 gene. This manipulation had several notable effects:
- An earlier date of tuberisation
- An increase in tuber yield
- Robust growth
- Early flowering
- Vigorous tuber sprouting
These findings suggest that increased sugar demand at the start of tuberisation might lead to the activation of germin3. Further studies indicated that the presence of the germin3 protein in cells allowed it to move to adjacent cells. This suggests that germin3 promotes potato tuberisation by helping to open pores, facilitating a massive influx of sugars necessary for tuber bulking.
This discovery potentially solves the 25-year-old mystery of how the transition from using specific sugar transporters to directly transferring sugars with the phloem, which greatly increases sugar delivery capacity, takes place.
Crucially, since germin3 acts downstream of leaf tuberisation signals that are sensitive to temperature, this finding offers a significant opportunity. It presents a route to developing potato varieties that can form tubers effectively even at higher temperatures. By bypassing this temperature sensitivity, it could become possible to grow potatoes, a calorie-dense crop, in areas of the world where they currently cannot survive, contributing to food security for growing global populations.
Dr Mark Taylor, who initiated this work before retiring, added that these experiments indicate germins may regulate other plant developmental processes besides tuberisation, including flowering and dormancy. This suggests opportunities to manipulate multiple aspects of plant development, potentially leading to yield increases in a wide variety of crops.
The James Hutton Institute, with sites including one in Invergowrie near Dundee, is where this impactful research took place. Potatoes in Practice, an event related to potato cultivation, is also planned at the institute’s Balruddery Farm in Invergowrie in August 2025. This work highlights the ongoing importance of plant science in addressing global challenges.
