This summer we saw that a heat wave can lead to severe drought. But what was less visible was the damage to plants that was caused by prolonged heat. “Because of the heat, the plants do not produce pollen and if there’s no pollen, then there’s no reproduction,” says plant physiologist Ivo Rieu. It is not necessarily noticeable on the outside of a plant, but plant fertility may suffer considerably from prolonged heat. Such conditions compromise the production of seeds and fruits like wheat, rice, tomatoes and beans. Increasing temperatures and prolonged heat mean that this problem will only get worse. And that is why Ivo Rieu and his colleagues at the Radboud Institute for Biological and Environmental Sciences are investigating methods for making agriculture and horticulture sustainable and climate-proof and looking at methods for improving food security. “There are three main preventative methods for ensuring that plant fertility does not decrease due to heat,” claims Rieu. “First of all, you can start growing crops in other locations. This has already been seen in Australia, for example, where vintners are moving to cooler areas. This will undoubtedly become a more common practice, but it may involve major changes to farming cultures. Imagine what it would be like if it was no longer possible to grow tomatoes in Italy?” A second solution would involve planting crops earlier in order to beat the most intense heat, but this method also has its drawbacks. Rieu and his colleagues are particularly interested in the third method, which involves enhanced protection against heat. “We have two major lines of research,” says Rieu. “First of all, we look at which plants can effectively withstand heat. We try to identify which genes work well and we then cross-breed plants accordingly.” Heat-resistant tomatoes Rieu cites the example of a Filipino tomato variety that is extremely heat-resistant. “We started by identifying the piece of DNA that protects these tomatoes from heat. We then added this DNA to the local tomatoes in our greenhouses to see how they responded to heat. When we saw that they responded well, we grew the same crossbred tomato variety in the southern Spanish countryside, and saw that these tomatoes also withstood the heat quite well.” This piece of ‘Filipino’ DNA is now also being used by plant-breeding companies. Hormonal sweating Just because the cross breeding of protective genes has worked well in tomatoes, it does not mean that it is always an option, stresses Rieu. There will not always be an available variety of plant that is able to withstand heat so well. One alternative would involve using biotechnology to protect plants artificially. “For example, it’s possible to inhibit a hormone, as a result of which plants perspire more and cool down, just like human beings. This has proven to be very effective.” By the same token, plants are also similar to human beings in that they only have a certain amount of energy at their disposal. “By using energy to protect itself against high temperatures, a plant cannot put as much effort into warding off disease, and vice versa. This is obviously something to keep in mind when we’re looking for solutions; it could pose a problem, but we could also use it to our advantage.” Photo by Wolfgang Hasselmann on Unsplash.