Tomatoes have a molecular trick to survive in extreme heat

Hot days, cool salads, and refreshing tomato slices – sounds like summer, doesn’t it? But have you ever wondered – how do tomatoes survive intense heat?

Under the scorching sun, as the mercury rises, some tomato varieties keep on thriving. A team of biologists based at Brown University decided to investigate.

Tomatoes surviving the heat

The experts wanted to identify the specific growth cycle phase when tomatoes buckle under heat, as well as the molecular mechanisms that shield them.

The findings could be a crucial key to protecting our food supply in the age of climate change. Indeed, agricultural productivity is already dancing on thin ice.

Our rising temperatures could slash crop yields by up to 16% with every additional degree Celsius of seasonal warming.

Lessons from evolution

Study co-author Sorel V. Yimga Ouonkap is a research associate in molecular biology, cell biology, and biochemistry at Brown.

Ouonkap noted that the scientists took some lessons from evolution to experiment with how best to speed up the adaptation process for varieties of tomato plants.

According to the researchers, it would take a long time to wait for evolution to weed out the vulnerable tomato varieties like Heinz in favor of those that can handle extreme heat – a process that might also jeopardize the qualities that make vulnerable crops commercially desirable.

Making tomatoes more tolerant of heat

“We’re trying to figure out thermoregulation at a molecular and cellular level, and identify what and where we need to improve so that we can target those in commercial plant cultivars and conserve everything about them except for this one aspect that makes them vulnerable to extreme heat,” explained Ouonkap.

“Over time, you can start accumulating different resistance mechanisms as the growing conditions continue to change.”

Thermotolerance, or the ability of a plant to withstand extreme temperatures, could be a promising way to confront climate change, noted study author Mark Johnson, a professor of biology at Brown.

“Imagine if you could just make a Heinz tomato more resilient to temperature stress without affecting the flavor profile or the way people experience the tomato,” Johnson said. “That would be a great advantage.”

Heat stress and plant reproduction

Johnson’s lab has studied plant reproduction for years. Yet, a gap remained: no studies examined what happens after pollen lands on the stigma during this crucial phase – a key to understanding how tomatoes survive extreme conditions.

Undeterred, Ouonkap dived into this unexplored area for his thesis project. He focused on the pollen tube growth phase of the plant reproductive cycle, studying different tomato varieties known for thriving in extra-hot growing seasons.

Collaborating with scientists from the University of Arizona, the experts learned that heat stress during just this phase limits fruit and seed production more in heat-sensitive than heat-tolerant tomato varieties.

It’s not all bad news. Ouonkap discovered that the heat-tolerant Tamaulipas tomato variety showed exceptional growth under high temperatures. His molecular analysis helped the team uncover the mechanisms that let this tomato survive intense heat.

Creating tomatoes to beat the heat

The researchers focused on tomatoes because different varieties can adapt to a range of extreme climates – providing clues to how species respond differently to environmental conditions.

Tomatoes are a valuable commercial crop all over the world, including some regions that are among the most vulnerable to extreme heat conditions. 

Having identified the beneficial molecular mechanisms, the next step is to determine specific techniques to enable tomatoes to grow in diverse climates.

One possible avenue? Creating a molecule that could prepare the pollen in the plants to withstand a heat wave, as Johnson explained.

Can more tomatoes survive?

“When the weather forecast showed two weeks of high temperatures during the pollen tube growth phase, the farmer would apply a product to plants that would change the gene expression so that the pollen would be resilient to heat,” said Johnson.

While this level of manipulation is still a vision and not yet a reality, the experts said this area of research is ripe for exploration.

The study is published in the journal Current Biology.

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