Role of Cytokinin Oxidase/ Dehydrogenase in Crop Improvement

The phytohormone cytokinin regulates various crucial functions of plant growth and development such as shoot apical meristem activity, flower development, vascular development etc. and also has negative role in lateral root development and root apical meristem activity. Cytokinin is degraded by cytokinin oxidase/dehydrogenase (CKX) irreversibly and reversible inactivation by glucosylation. Various homologous genes of CKX have been identified in Arabidopsis and in many other crop plants. The root specific expression of CKX showed positive results for larger root with higher lateral root numbers and higher root to shoot biomass. The site-specific manipulation of CKX gene has been done in crops like wheat, barley, maize, rice, legumes and horticultural crops to regulate the cytokinin levels in the particular tissues to enhance the yield, tolerance to various abiotic stresses (drought, salt, lower soil fertility), biofortification for many micronutrients (Zn, Fe) in the seed, propagation, etc. And the use of modern techniques in manipulation of CKX have been started to improve the crop plant and the outcome is very promising for the future application in commercial agricultural activities.