Scientists Reveal Key Genetic Mechanism that Improves Sorghum's Drought Tolerance

A research team from the Centre for Research in Agricultural Genomics (CRAG) led by Ana I. Caño-Delgado has identified a molecular mechanism that enables sorghum plants to thrive under water-scarce conditions. This discovery could pave the way for developing drought resistant crops to help secure global food supplies in the face of increasing climate crisis.

Sorghum is a vital crop for millions of people living in regions prone to drought, such as Africa, Southeast Asia, and Central America. Despite being naturally more drought-resistant than other cereals, extreme droughts still cause considerable reductions in sorghum yield. The CRAG-led research team focused on understanding how plants respond to drought at a molecular level, and identified key genes that could be modified to boost drought resilience. The research focused on the plant steroid hormones called brassinosteroids and their receptor BRASSINOSTEROID-INSENSITIVE 1 (BRI1). The team discovered that by modifying the BRI1 receptor of sorghum (known as SbBRI1), sorghum plants can significantly improve their drought tolerance.

The study also revealed that the SbBRI1 receptor plays a dual role. Under normal conditions, it regulates lignin biosynthesis through a downstream protein called SbBES1. Lignin is critical in cell wall formation, but it also requires significant energy and resources. However, during drought conditions, this process changes. The SbBES1 protein becomes less active, and the plant switches to a different metabolic pathway that activates flavonoid production. The metabolic shift allows the plant to conserve energy, improve photosynthetic efficiency,  and protect itself from the harsh conditions brought on by drought.

The researchers generated mutant sorghum plants with a loss-of-function mutation in the SbBRI1 gene, to produce inactive BRI1 receptors. The mutant plants were tested under controlled drought conditions, and the results were remarkable as the mutant plants displayed significantly improved water retention and photosynthetic efficiency.

For more details, read the article in CRAG News.