Barley modified for tolerance to drought and nutrient deficiencies

The bGLU:CKX1 barley line has been genetically modified by inserting the Arabidopsis thaliana cytokinin dehydrogenase 1 gene under the control of the root-specific β-glucosidase promoter from maize.

Cytokinin dehydrogenases catalyze the irreversible degradation of cytokinins in a single enzymatic step by oxidative side chain cleavage. Cytokinins, which are chemically N6-substituted purine derivatives, are a class of plant hormones that regulate cell division as well as a large number of developmental events in plants. An important trait regulated by cytokinin is the size of the root system.

A reduced cytokinin status in plants (including barley) causes an enhanced root system which might render plants more tolerant to drought and nutrient deficiencies in the soil. Crop yield is often limited by the availability of water and soil-derived mineral nutrients. A larger root system may enable plants to get better access to water and nutrient resources, therefore to better cope with adverse environmental conditions.

cv. Golden Promise

bGLU:CKX1

The transgenic line shows an up to 8-fold higher CKX enzyme activity in roots as compared to the wild type. In contrast, CKX enzymatic activity in the leaves of transgenic plants is similar to the control plants.

The cytokinin dehydrogenase 1 gene is under the control of the root-specific β-glucosidase promoter from maize.

The Hygromycin B phosphotransferase selection marker is under the control of the TMV 35s promoter.