Methods and compositions for modulating plant development are provided.
Polynucleotide sequences and amino acid sequences encoding cytokinin
oxidase polypeptides are provided. The sequences can be used in a variety
of methods including modulating root development, modulating floral
development, modulating leaf and/or shoot development, modulating seed
size and/or weight, modulating tolerance under abiotic stress, and
modulating resistance to pathogens. Polynucleotides comprising CKX
promoters are also provided. The promoters can be used to regulate
expression of a sequence of interest. Transformed plants, plant cells,
tissues, and seed are also provided.