Biotech Updates

Downregulation of Cytokinin Oxidase 2 Increases Tiller Number and Improves Rice Yield

December 9, 2015

Cytokinins are hormones that affect plant growth and development. The level of cytokinins in plant cells is regulated in part through cytokinin oxidase/dehydrogenase (CKX). Among them, CKX2 has been implicated in regulation of rice grain yield.

To downregulate OsCKX2 expression, the team led by Su-Ying Yeh of Academia Sinica in Taiwan chose two conserved glycosylation regions of OsCKX2 for designing artificial short hairpin RNA interference genes (shRNA-CX3 and -CX5, representing the 5′and 3′ glycosylation region sequences, respectively) for transformation by the Agrobacterium-mediated method. For each construct, five transgenic rice lines with reduced CKX2 expression were developed.

Transgenic plants in the greenhouse were greener and more vigorous with delayed senescence, compared to the wild type. In field experiments, both sets of transgenic rice plants produced more tillers and grains per plant and had a heavier 1000 grain weight than the wild type. The increases in grain yield were highly correlated with increased tiller numbers.

These results demonstrate that specific suppression of OsCKX2 expression through shRNA-mediated gene silencing leads to enhanced growth and productivity in rice by increasing tiller number and grain weight.

For more information, read the full article in Rice.