BES1 negatively regulates the expression of to control the endogenous level of ethylene in .

Quantitative reverse transcription PCR (qRT-PCR) analysis and expression showed that was highly expressed in the shoots of Arabidopsis seedlings under light conditions. Exogenously applied aminocyclopropane-1-carboxylic acid (ACC) enhanced the expression of , whereas Co ions suppressed its expression. In comparison with wild-type seedlings, the knockdown mutant produced less ethylene, which resulted in the inhibited growth of Arabidopsis seedlings. Exogenously applied brassinolide reduced the expression of expression was increased in , a brassinosteroid (BR)-deficient mutant; however, it was decreased in , a brassinosteroid insensitive 1-EMS-suppressor 1 (BES1)-dominant mutant. In the putative promoter region of , 11 E-box sequences for BES1 binding but not BR regulatory element sequences for brassinazole-resistant 1 (BZR1) binding were found. Chromatin immunoprecipitation assay showed that BES1 could directly bind to the E-boxes located in the putative promoter region of . Less ethylene was produced in seedlings compared with wild-type seedlings, suggesting that the direct binding of BES1 to the promoter may negatively regulate expression to control the endogenous level of ethylene in Arabidopsis seedlings.