Show-Me State Times

Researchers at the University of Missouri have found that soybeans use a natural defense called differential transpiration to protect their reproductive tissues during periods of heat and drought. This process allows the plants to keep their stomata—small pores involved in cooling—open on flowers and pods, while closing them on leaves.

“Soybeans keep their stomata — tiny pores used for plant breathing and cooling by evaporation — open on their flowers and pods to allow for transpirational cooling while simultaneously closing the stomata on their leaves,” said Ron Mittler, Curators’ Distinguished Professor of Plant Science and Technology at the University of Missouri. “By selectively cooling only the reproductive tissues and closing the stomata on the larger leaf area, these plants can save a substantial amount of water — upwards of 95 percent.”

Mittler explained that understanding this response could help develop more resilient crop varieties through breeding or genetic engineering. “This discovery opens the door to new strategies in crop improvement,” Mittler said. “If we can enhance differential transpiration through genetic engineering or breeding — for instance, by increasing stomatal density on reproductive tissues — we may be able to develop crops that are better equipped to handle tough weather conditions.”

The study, titled “Differential transpiration occurs in soybean under a wide range of water deficit and heat stress combination conditions,” was published in Physiologia Plantarum. Co-authors include Ranjita Sinha, María Ángeles Peláez-Vico, and Felix B. Fritschi at Mizzou. The research builds on earlier findings published in New Phytologist and Plant Physiology.

Funding for this work came from two grants provided by the National Science Foundation.