The cloning of two novel genes that encode cytokinin oxidase/dehydrogenase (CKX) in barley is described in this work. Transformation of both genes intoArabidopsisand tobacco showed that at least one of the genes codes for a functional enzyme, as its expression caused a cytokinin-deficient phenotype in the heterologous host plants. Addi-tional cloning of two gene fragments, and anin silicosearch in the public expressed sequence tag clone databases, revealed the presence of at least 13 more members of the CKXgene family in barley and wheat. .
