Methods and compositions for modulating plant development are provided. Polynucleotide sequences and amino acid sequences encoding isopentenyl transferase (IPT) 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 senescence, modulating seed size and/or weight, and modulating tolerance of plants to abiotic stress. Polynucleotides comprising an IPT promoter are also provided. The promoter can be used to regulate expression of a sequence of interest. Transformed plants, plant cell, tissues, and seed are also provided.