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A plant’s response to drought

Written by Rashmi Shivni

Researchers determined the genetic mechanisms of plant growth, which may help increase crop yields in times of drought.

Arabidopsis plants were grown under well-watered (left) or drought (right) conditions.

Credit: Zhouli Xie.

In recent years, the American Southwest has been hit with severe, lasting droughts that make it difficult for farmers and agriculturalists to keep up with the demand for year-round produce. This is just one of the far-reaching effects of climate change—problems that scientists are now tackling at the molecular level.

Researchers at Iowa State University have spent nearly 15 years investigating the genetic mechanisms behind plant growth and development. In their latest research, published in Nature Communications, the scientists uprooted some new information about two key pathways that govern plant growth and responses to drought.

“Plants have to deal with various stresses, so it’s good for us to know how they do this mechanistically,” said Yanhai Yin, corresponding author of the study.

Yin and his colleagues studied these mechanisms inArabidopsis, or thale cress. They discovered that the two interacting pathways—the brassinosteroid hormone (BR) and drought response—depend on the transcription factors BES1 and RD26, respectively.

Under normal conditions, BRs activate BES1 and its family of proteins to regulate plant growth and development. In contrast, RD26 is active only when plants are extremely parched, as they try to conserve energy by slowing growth.

“We found that these pathways are kind of like ‘frenemies’ that stay together but ‘antagonize’ each other most of the time,” Yin explained. Both transcription factors bind the same promoter sites simultaneously, but only one pathway becomes active, depending on the environmental conditions.

Now that the ISU researchers have a view of the mechanisms’ roots, they need to see how far its roots go. In upcoming work, they hope to further investigate how RD26 is regulated by drought, how BES1 and RD26 inhibit one another, and how the two proteins bind in the same regions of the genome and remain antagonistic. Other areas of investigation include whether additional stressors, such as salt stress or bug bites, rely on the same genetic mechanisms and if other plants share similar pathways.

The ultimate goal, though, is to use the knowledge to fine-tune and favor growth no matter the environmental condition. “We believe there are similar mechanisms present in a variety of cash crops, and hopefully, we can use this model to improve stress tolerance and boost crop performance under drought or other stressful conditions,” Yin said.