The highest transient GUS expression was observed at 22 °C, in which 64% of total calluses showed GUS activity. The ratio of GUS-stained calluses to totalluses decreased by 85% at 20°C(54.2% of total calluses) and by 69% at 24°C(44.2% of total calluses) compared with that at 22°C with EHA101. Suboptial temperatures for transformation depend on the combination of Agrobacterium strains and plant mate rials. For example, when pEHA101 was use Dillen et al. (1997), GUS activity wahierher at 1900 than at 25°C, whereas the activity was higher at 25 oC at 19 °C when pGV2260 and pMP90 were use than The results of our study, in which EHA101 was used as the Agrobacterium strain, showed that transient GUS expression was higher at 20 than at 24°C, this in good agreement with Dillen et al. (1997) usi EHA101. Light and temperature are generalltant factors affecting biological responses. Co-cultivation has been carried out in darkness for ma of plants. Ikeda et al. (1997) also co-cultivated Welsh onion with Agrobacterium in darkness at 22 °C. In preliminary experiments, we compared light and dark conditions with respect to transformation efficiency No significant differences between the cultures in light and dark conditions were observed for transformation efficiency in garlic(data not shown).