Biologists at Brown University have made a significant discovery regarding the vulnerability of tomato plants to extreme heat, identifying the specific phase of the growth cycle most susceptible to heat stress and the molecular mechanisms that could enhance heat tolerance. This study, published in Current Biology, provides valuable insight into a critical strategy for protecting crops as global temperatures rise and climate change threatens agricultural productivity. Rising temperatures are predicted to decrease crop yields by 2.5% to 16% for every additional degree Celsius of seasonal warming, making it increasingly important to find ways to adapt crops to these changing conditions.
The researchers focused on tomato varieties that have shown the ability to produce fruit in exceptionally hot conditions. According to Sorel V. Yimga Ouonkap, a research associate in molecular biology at Brown, the team sought to harness insights from evolution to speed up the adaptation process. While natural evolution could eventually weed out vulnerable tomato varieties, this process could take many years and may also compromise desirable traits in commercially valuable crops. The researchers instead aim to identify specific aspects of heat tolerance that can be targeted without affecting other essential qualities, such as flavor and appearance.
Understanding thermotolerance, or a plant’s ability to withstand extreme temperatures, is a promising avenue for climate adaptation. Mark Johnson, a professor of biology at Brown and co-author of the study, emphasized the potential benefit of making heat-sensitive tomato varieties more resilient without altering their key characteristics. For instance, if scientists could modify a popular tomato variety like Heinz to better tolerate heat stress, it could provide a significant advantage in maintaining crop yields in warmer climates.
A key aspect of the study focused on plant reproduction, specifically the phase of pollen tube growth during fertilization. Previous research has often looked at how heat stress affects overall plant growth or reproductive structures, but little attention has been given to the critical post-pollination phase. Ouonkap’s research investigated how heat affects the growth of pollen tubes—the structures that deliver sperm cells to the ovule—in tomato plants. Using varieties of tomatoes known for their heat tolerance, Ouonkap and his colleagues exposed pollen tubes to high temperatures in controlled laboratory conditions. They found that exposure to heat during the pollen tube growth phase resulted in a more significant reduction in fruit and seed production in heat-sensitive tomato varieties than in heat-tolerant varieties. Notably, the Tamaulipas variety of tomato, which is native to Mexico and known for its heat tolerance, showed enhanced pollen tube growth even under high temperatures.
This finding is particularly important because it highlights the potential for breeding or modifying tomatoes to enhance their resilience to heat stress during the reproductive phase, which is crucial for successful fruit and seed production. The ability of different tomato varieties to adapt to extreme climates makes them an ideal model for studying how plants respond to environmental stressors. As tomatoes are a major commercial crop grown around the world, from California to the Mediterranean, improving their heat tolerance could have significant implications for global food security, especially in regions that are increasingly vulnerable to heatwaves.
The next step in this research involves developing specific techniques to enable tomato plants to grow successfully in different climates. One possibility, as Johnson suggested, could be the development of small molecules that help prime the pollen to withstand heat stress. In a hypothetical scenario, farmers could apply such a product during periods of expected high temperatures to enhance the heat resilience of tomato pollen, ensuring continued fruit production even during extreme heat events.
While this kind of molecular intervention is still far from being realized, the research represents an exciting opportunity for advancing agricultural practices in the face of climate change. With the molecular mechanisms behind heat tolerance now identified, future studies may explore ways to apply these insights to other crops, providing a vital tool for maintaining food security in an increasingly unpredictable climate.
Source: Brown University