This invention provides a method for producing a plant with enhanced or suppressed growth through introduction of a mutated gene and a plant including such a mutated gene. This invention provides a method for producing a plant with enhanced growth or suppressed growth. Such method includes a step of introducing a gene encoding a chimeric myosin protein into a host plant so as to transform the host plant, wherein the chimeric myosin protein comprises: a neck domain, a coiled-coil domain, and a globular tail domain from a myosin protein involved in cytoplasmic streaming of a donor plant and a motor domain from a myosin protein other than the myosin protein of the host plant, which has sliding velocity that is higher or lower, respectively, than that of the myosin protein involved in cytoplasmic streaming of the donor plant.
