Scientists Seek to Grow More Heat-Tolerant Tomatoes

As climate change worsens drought events, scientists are finding ways to make crops more resilient. Such is the case in a new study where biologists at Brown University explored tomato traits and growth cycles that are most durable against heat stress.

Crop yields are expected to decline between 2.5% to 16% for each degree Celsius of warming, the study warned. With global temperatures already surpassing 1.5 degrees Celsius warming for the calendar year compared to pre-industrial times and droughts continuing to worsen in terms of frequency, severity and length, crops are becoming more at risk to heat stress.

In response, scientists experimented with tomato plants to study their pollen tube growth phase, a part of plants’ growth cycles when the pollen tube grows through the pistil to bring the mature male germ cells to the mature female germ cells for fertilization, as explained in the Atlas of Sexual Reproduction in Flowering Plants.

The team’s goal was to find which tomato varieties are best suited to withstanding drought and heat and use their genetics to determine how to make other varieties more durable to these conditions.

“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,” Sorel V. Yimga Ouonkap, an author of the study and a research associate at Brown University, said in a statement. “Over time, you can start accumulating different resistance mechanisms as the growing conditions continue to change.”

The researchers selected tomato plants native to the Philippines, Russia and Mexico and noted changes in gene expressions when the plants were exposed to heat. The research team and its partners at the University of Arizona found significant differences in heat-tolerant tomatoes and the varieties that were more sensitive to heat. Heat-tolerant tomatoes experienced more growth, while heat-sensitive varieties experienced limitations to fruit and seed production during the pollen tube growth phase. 

From there, the scientists were able to look deeper into the biology of the plants to identify what characteristics make this heat- and drought-tolerance possible, paving the way for more drought-resilient crops in the future. The authors published their findings in the journal Current Biology.

With more research, the findings could help inspire a type of molecule product that could be applied to more heat-sensitive tomatoes ahead of a pollen tube growth phase.

“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,” explained Mark Johnson, an author of the study and a professor of biology at Brown University.

This would allow farmers to continue to grow desirable tomato varieties, even if they are naturally more vulnerable to heat and drought.

“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.”