Biologists have uncovered what enables certain tomato varieties to withstand heat, which could provide valuable information for helping crops adjust to climate change.
By examining tomato types that thrive in extremely hot growing seasons, researchers at Brown University have pinpointed the specific growth stage when tomatoes are most affected by high temperatures, along with the molecular processes that enhance their heat resistance.
The findings, published in Current Biology, might play an essential role in safeguarding the food supply against the unpredictable impacts of climate change, according to the researchers. The study highlighted that agricultural output is highly susceptible to climate variations, warning that for every additional degree Celsius of warming during growing seasons, crop yields could drop by 2.5% to 16%.
Taking cues from the process of evolution, the scientists experimented on how to accelerate the adaptation of specific tomato varieties, as explained by study co-author Sorel V. Yimga Ouonkap, a research associate in molecular biology, cell biology, and biochemistry at Brown. Instead of waiting long periods for evolution to phase out susceptible tomato varieties like Heinz in favor of those that can withstand extreme heat—which could also risk losing desirable commercial qualities—the researchers aimed to streamline the adaptation process.
“Our goal is to understand how plants regulate temperature at both the molecular and cellular levels so we can determine what modifications are needed to enhance heat tolerance in commercial plant types while preserving their other valuable traits,” Ouonkap said. “This approach would allow us to accumulate various resistance mechanisms as cultivation conditions evolve.”
According to Mark Johnson, a biology professor at Brown and another author of the study, grasping thermotolerance—plants’ capability to endure extreme temperatures—is a promising avenue to tackle climate adaptation.
“Imagine enhancing a Heinz tomato’s resilience to temperature fluctuations without altering its taste or how consumers perceive it,” Johnson noted. “That could be a significant benefit.”
Focusing on Plant Reproduction
Research on plant reproduction has been a longstanding interest in Johnson’s lab. While past studies have generally explored how heat stress impacts plant growth or the development of essential reproductive structures, little had been examined regarding what occurs after pollen lands on the stigma during reproduction, Johnson elaborated.
In his thesis project, Ouonkap investigated the pollen tube growth stage in the tomato reproduction cycle. He examined different tomato cultivars known for their ability to produce fruit during very hot seasons. The tomatoes studied originated from the Philippines, Russia, and Mexico and were cultivated in Brown’s Plant Environment Center.
Working with researchers from the University of Arizona, Ouonkap looked into how high temperatures impact pollen growth within tomato flowers. He evaluated how gene expression alters when pollen produced under optimal greenhouse conditions undergoes heat exposure in a petri dish.
The team’s collaborators in Arizona discovered that heat stress experienced only during the pollen tube growth phase significantly hampers fruit and seed production in heat-sensitive tomato cultivars compared to heat-resistant ones. Notably, Ouonkap’s research revealed that pollen tubes from the Tamaulipas tomato variety, known to tolerate heat, showed enhanced growth in elevated temperatures. His molecular analysis of these pollen tubes enabled the research team to identify the mechanisms linked to thermotolerance.
Researchers consider tomatoes to be an excellent subject for this type of exploration. The diverse adaptability of various tomato varieties to extreme climates provides insights into how different species respond to changing environmental conditions. Additionally, tomatoes are a crucial commercial crop globally, thriving in regions like the Mediterranean, Egypt, Turkey, and California—areas particularly vulnerable to extreme heat.
With molecular mechanisms identified, the next phase involves developing specific methods to promote tomato growth across various climates. In a hypothetical scenario, scientists might create a small compound that prepares pollen to endure heat waves, Johnson explained.
“When forecasts predict a couple of weeks of high temperatures during the pollen tube growth phase, farmers could apply a product that modifies gene expression to ensure the pollen withstands the heat,” he said.
While such advancements are still a distant prospect, researchers believe this area of study is ripe for further investigation.
This research was funded by the National Science Foundation (IOS-1939255), with further support from the United States Department of Agriculture National Institute of Food and Agriculture (2020-67013-30907, 2024-67012-41882) and the National Institutes of Health (5R35GM139609, PI AEL).