Alfalfa (Medicago sativa L.) is an important legume forage crop with great economic value. However, the growth of alfalfa is seriously affected by an inadequate supply of water, making drought the major abiotic environmental factor that affects alfalfa production. To enhance alfalfa drought tolerance, Guangshun Zheng of the Chinese Academy of Sciences overexpressed the Arabidopsis Enhanced Drought Tolerance 1 (AtEDT1) gene into alfalfa via Agrobacterium-mediated transformation.

Drought stress treatment resulted in higher survival rates and biomass, as well as reduced water loss in transgenic plants. Furthermore, transgenic alfalfa plants had increased stomatal size, but reduced stomatal density, contributing to the reduced water loss. Moreover, the transgenic  plants exhibited larger root systems with larger root lengths, root weight, and root diameters than wild type alfalfa plants.

The transgenic alfalfa plants had reduced membrane permeability and enhanced expression of drought-responsive genes compared to wild types. In field trials, the plants grew better and showed enhanced growth performance with increased biomass.

Expression of AtEDT1 improved the growth and enhanced drought tolerance in alfalfa. This study provides new alfalfa germplasm for use in forage improvement programs, and may help increase alfalfa production in arid lands.

For more on this study, read the article in Frontiers in Plant Science.