Transgenic Barley With Modulated Cytokinin Level - Yield Improvement and Enhanced Stress Tolerance.

Barley, Hordeum vulgare, is an agriculturally important crop. New techniques of molecular cloning and plant transformation accelerate classical breeding techniques and produce barley plants with enhanced traits.

Cytokinins are plant hormones controlling many physiological processes including stress tolerance and root formation. Cytokinins are irreversibly degraded by cytokinin dehydrogenase (EC 1.5.99.12; CKX), which is a principal factor to control cytokinin levels in plants.

For modulation of the cytokinin level in barley, constructs with cytokinin dehydrogenase with altered targeting under the control of potentially root specific promoter were prepared. All intended transgenic barley lines were prepared, confirmed and then analyzed in T2 generation of homozygous plants. Three unique transgenic barley lines with differently localized CKX showed distinct phenotypes.