Barley modified for tolerance to drought and nutrient deficiencies

The pEXP:CKX1  barley line has been genetically modified by inserting the Arabidopsis thaliana cytokinin dehydrogenase 1 gene under the control of the root-specific promoter derived from the expressed protein gene LOC_Os04g11040.1 of rice

The Arabidopsis cytokinin oxidase/dehydrogenase 1 enzyme (CKX1) catalyzes the irreversible degradation of the hormone cytokinin in a single enzymatic step by oxidative side chain cleavage causing ectopic depletion of cytokinins in roots. The modification therefore results in the irreversible degradation of the cytokinin hormone that leads to enhanced root meristem proliferation and therefore enhanced root system development which might render the modified plant more tolerant to drought and nutrient deficiencies in the soil.

In addition, the transgenic line has also integrated the hpt selection gene coding for hygromycin phosphotransferase that confers resistance to the antibiotic Hygromycin B. This antibiotic resistance has been used in in vitro culture to screen for genetically modified cells and plants.

cv. Golden Promise

pEXP:CKX1

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

The cytokinin dehydrogenase 1 gene is under the control of the root-specific promoter derived from the expressed protein gene LOC_Os04g11040.1 of rice.

The Hygromycin B phosphotransferase selection marker is under the control of the promoter region from Zea mays polyubiquitin gene.