Compositions and methods for modulating plant development and for increasing yield in a plant are provided. The compositions include a PC4 sequence. Compositions of the invention comprise amino acid sequences and nucleotide sequences selected from SEQ ID NOS: 1 and 2 as well as variants and fragments thereof. Nucleotide sequences encoding the PC4 molecule are provided in DNA constructs for expression in a plant of interest are provided for modulating the level of a PC4 sequence in a plant or a plant part are provided. The methods comprise introducing into a plant or plant part a heterologous polynucleotide comprising a PC4 sequence of the invention. The level of the PC4 polypeptide can be increased or decreased. Such method can be used to increase the yield in plants in one embodiment, the method is used to increase grain yield in cereals.
