Isolated or purified nucleic acid molecules encoding polypeptides having cyclin-dependent kinase (CDK) inhibitor-like activity; vectors; host cells; polypeptides having CDK inhibitor-like activity; nucleic acid constructs for suppression of CDK inhibitor-like activity; methods of suppressing and up-regulating the expression of one or more CDK inhibitor-like genes in a maize cell, tissue, organ, or plant; a maize cell, tissue, organ, or plant in which the expression of a CDK inhibitor-like gene has been suppressed or up-regulated in accordance with such methods; and a seed (and the oil and meal thereof) obtained from a plant in which the expression of one or more CDK inhibitor-like genes has been suppressed or up-regulated.