The actin-depolymerizing factor 4 gene (ADF4) of Arabidopsis thaliana was cloned and sequenced (Figs.1, 2). The plant expression vector with ADF4 was constructed and transformed into tobacco by Agrobacterium tumefaciens. Molecular identification showed that the ADF4 gene was integrated into the genome of tobacco and expressed in transgenic tobaccos assayed by PCR and RT-PCR (Fig.3). Expression of an Arabidopsis thaliana ADF4 gene in tobacco resulted in morphological change of plants. The effects of ADF4 on transgenic tobaccos growth were as follows: the hypocotyls of transgenic plants were wavy, especially in darkness, whereas those of the control were straight (Fig.4A); the root hairs of transgenic plants were less than the control, and they were also wavy (Fig.4B); the parenchyma cells of transgenic plants were larger than the control and the arrangement of vascular bundle was out of order (Fig.4C); the flowering time of T(2) line was at least 7 days later than the control; the pollen tubes of transgenic plants were shorter than those of the control (Fig.4D).