ABSTRACT. CsICE1 is thought to be involved in hardiness resistance of tea plants. Using seedling cuttings of biennial Wuniuzao in this study, the pattern of CsICE1 expression under cold temperature (4°, -5°C), drought [20% polyethylene glycol 6000 (PEG-6000)], and plant hormone [200 mg/L abscisic acid (ABA), 1 mg/L brassinolide (BR)] treatment was studied by real-time quantitative PCR. Additionally, stress resistance, such as the freezing resistance of CsICE1, was studied using Arabidopsis lines transformed with sense or anti-sense CsICE1 via Agrobacterium tumefaciens infection. Our results showed that CsICE1 mRNA could be induced under -5°C, PEG, ABA, or BR treatment, although the pattern of expression differed for all treatments. Compared to wild type (WT) and anti-sense ICE1 transgenic lines, sense lines displayed higher relative germination rates under salt and drought stress. After freezing treatment, the sense transgenic lines overexpressing CsICE1 showed a higher survival rate, increased levels of proline, and decreased levels of malonaldehyde. Conversely, compared with WT, anti-sense ICE1 transgenic lines had lower proline levels and higher malonaldehyde levels under freezing conditions. Our study 11260 Z.T. Ding et al. ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 14 (3): 11259-11270 (2015) indicates that CsICE1 is an important anti-freezing gene and that overexpression of CsICE1 can improve cold resistance and enhance salt and drought tolerance of transgenic lines.