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.



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