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While nothing says "summer" quite like the taste of a perfectly ripe tomato, excessive heat during the growing season can prevent tomato plants from bearing fruit.

Gloria Muday, the Charles M. Allen Professor of Biology at Wake Forest University, studies tomatoes and how to make them more heat-resistant. Her research laboratory focuses on understanding the signals that control plant growth and development. Muday is also part of a team of scientists in North Carolina working with farmers to develop and apply new agricultural approaches and crop varieties that thrive in an environment that challenges crop success.

Muday explains the science behind tomatoes and shares how commercial growers and backyard gardeners can help tomatoes beat the heat.

What happens in a tomato plant in extreme heat?

The heat causes the tomato blossom's pollen tube to explode before fertilization, preventing the pollen from reaching the plant ovary and setting fruit. Pollen really is the weak link in high-temperature response.

We found that when pollen is warmer, it produces more reactive oxygen species. At high levels, these damaging molecules cause the pollen to fail or explode, and the plant can't produce seeds and fruits.

What protects some tomatoes from high temperatures better than others?

We're using a number of genetic approaches to get at that question. We began by working with a tomato that does not produce good levels of flavonol compounds. Flavonoid compounds are important protectors. They are antioxidants, and they can convert the dangerous reactive oxygen species to less damaging compounds.

We have tried to identify natural variants of plants that produce more flavonols and to create plant lines that overproduce these molecules. We have found that they are protective against high temperature stress, resulting in plants that are much more thermo-tolerant. We're told to eat purple vegetables and fruits because they are rich in antioxidants. The antioxidants are good for people and they are also good for plants. They protect them from the damage of high-temperature stress.

What varieties thrive in the heat?

One of our favorites right now is tamaulipas. It is from the state of Tamaulipas in Mexico and can withstand temperature stress. Another favorite is Empress tomatoes. They are high in antioxidants, heat-tolerant and have a beautiful purple color.

Why is it critical that we develop heat-resistant tomatoes? What's at stake?

Tomatoes are an important part of our diet, and their adaptability has helped make them an important part of the global food supply. Where tomato crops thrive has shifted because it's warmer than it was 10 years ago.

Our studies, and others that try to understand the effect of high temperature on plant growth and development, are designed to lead to crops that are better at dealing with this stress. If we understand why a particular plant fails at reproduction under high temperatures, we can do other experiments to engineer or breed plants that are more resistant to high temperature stress. And, this can increase our food supply in a changing climate.

What are the implications of your research for backyard gardeners?

Our work translates not just to agricultural supply chains and farmers, but also to home gardeners. First, gardeners can select varieties that are adapted to their local climate. Some plants do better under high-temperature conditions, so those who live in the South may need to select those.

Still, full sun all day may be too much for tomatoes grown in certain climates, so gardeners may also need to select growth conditions that are a little more sheltered to protect the plants and increase watering to balance the effect of the high temperatures. Second, home gardeners can help their tomatoes thrive by planting them earlier in the season.

One of the challenges with growing tomatoes is when they stop producing fruit, we think, "What did I do today?" But, the question we should ask is, "What could I have done three or four weeks ago when the pollination was occurring, so that the plants could produce the seeds and the fruits?" The reproduction process that yields fruit occurs weeks before we see the first tomato.