The objective of the present invention is to isolate and identify genes responsive to plant hormones, such as, brassinolide, and to provide these genes and their use. The present inventors found two novel genes (referred to as OsBLE1 gene and OsBLE2 gene) whose expressions are markedly increased by brassinolide and auxin, using DNA microarray techniques and Northern blotting. Transformed rice plants were produced using Agrobacterium EHA101 which comprise antisense polynucleotide against OsBLE1 and OsBLE2 under the control of the CaMV35S promoter in a binary vector pIG121-Hm. As a result, the transformed rice plants exhibited inhibition in stem and leaf growth as compared with controls which carried the vector alone.