The present invention provides methods for modulating the growth and/or yieldof plants. In particular the methods comprise the use of agents whichfunctionally inhibit the expression of plant D-like cyclin inhibitorsincluding isolated polynucleotide sequences which interact with DNA or RNAencoding proteins capable of binding plant D-like cyclins. Further, thepresent invention provides recombinant polynucleotide sequences, vectors andhost cells which encode proteins capable of binding to and inactivating theactivity of plant D-like cyclin/cyclin dependent kinase complexes preventingplant cells from exiting the cell cycle. Methods for determining and agentswhich are inhibitors of the BRO cyclin dependent kinase inhibitor proteinswhich are capable of modulating plant cell cycle progression are alsoprovided. Methods for the production of transgenic plant cells and plants withincreased growth rates and yields when compared to wild-type plants are alsoprovided.
