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New heat-proof tomato varieties in the face of climate change

People love tomatoes so much that they are now the most important vegetable crop worldwide. But as world temperatures rise, the risk of losing this vital source of food has become very real. The EU-funded TomGEM project has identified new varieties with better heat tolerance to ensure citizens can continue to enjoy all the tasty tomato-based foods they adore for a very long time still to come.

©Marcin #135547767, source: 2021

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We’ve all heard our parents or grandparents tell us how tomatoes used to taste better back in the day. While this could easily be dismissed as misplaced nostalgia, the sad truth is that, if nothing changes, we could soon be telling our grandchildren the exact same story. In recent years, temperature rises across Europe have caused up to 80 % drops in tomato production. Maintaining yield stability under harsh temperature conditions without compromising on quality is now the name of the game.

This is the context in which the EU-funded TomGEM project came to be. The project aimed to design heat-tolerant tomato varieties and come up with novel crop management practices in the face of climate change. “TomGEM builds upon the complementary expertise and skills of internationally recognised laboratories and experienced tomato producers and breeders. Together, we investigated the effects of elevated ambient temperatures on flower organ initiation, pollen fertility, fruit set, fruit growth and postharvest behaviour,” says project coordinator Mondher Bouzayen, professor of Biotechnology at the National Polytechnic Institute of Toulouse.

Ideal temperatures for tomato growth fluctuate between 21 and 29 °C during the day and 18 and 21 °C at night. Anything beyond these thresholds will have negative effects on fruit set and quality. As Bouzayen points out, many studies have also linked higher temperatures with a decrease in tomato yield. In other words, the only way forward is to identify tomato genotypes that can withstand and even thrive under harsh temperature conditions.

Pathways to improved yield

“Our teams had access to a large collection of tomato germplasm from across the world. We screened over 2 000 genotypes corresponding to natural or induced variations in different locations and evaluated their performance with regards to heat stress. To do so, we used a common set of phenotypic descriptors and environmental parameters,” Bouzayen explains.

The results of this large investigation are stored in PhenoTomGEM, a web-based database populated by all project partners. Within all this data is a precious list of superior genotypes with high tolerance to heat stress and high yield stability, but also new genes and new markers that will help tomato breeders create tomato varieties better suited to high temperature conditions.

A total of 18 genotypes were shortlisted, seven of which exhibit top performance in the three test countries of Bulgaria, Italy and Spain. But that’s not all. The project team also unveiled what they came to call the “most powerful toolkit” – a list of determinants of pollen fertility under high temperature conditions. These shall serve as a great starting point to develop new heat-resistant varieties. Other project deliverables include: a platform speeding up the search for candidate genes (TomExpress); a study of 4 000 existing tomato mutants; a plant-based bio-stimulant that can increase tomato tolerance to high temperature; a set of best management practices; and new tomato hybrids that are already turning heads in the sector. The project’s variety ‘Aleno sartse’ (Ruby Heart) even won the innovation prize at the XXVII International Agricultural Exhibition in 2018.

All in all, TomGEM is a goldmine of information for stakeholders looking to ensure that future generations will be able to enjoy tasty tomatoes in sufficient quantities. As Bouzayen says it himself, “we now have a greater understanding of the genetics behind tolerance and susceptibility to higher temperatures. We found signposts located in the tomato genome that will point breeders towards varieties with better heat tolerance, and we have devised novel management practices better suited to the new cultivars and changing growth conditions.”

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Project details

Project acronym
Project number
Project coordinator: France
Project participants:
United Kingdom
Total cost
€ 5 671 945
EU Contribution
€ 4 993 506
Project duration

See also

More information about project TomGEM

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