Abstract
DREBs are transcription factors that interact with a cis-acting DRE sequence and activate the expression of downstream genes involved in water or temperature stress responses and tolerance in Arabidopsis thaliana. Previously, we performed a comprehensive analysis of DREB2-type genes in rice. We reported that transgenic A. thaliana plants overexpressing OsDREB2B showed enhanced expression of stress-responsive genes and improved drought- and heat shock-stress tolerance. These results suggest that OsDREB2B is a key gene encoding a transcription factor that functions in stress tolerance in rice. However, transgenic rice expressing OsDREB2B at high levels did not show significantly improved stress tolerance as compared to control plants, though OsDREB2B showed high transactivation activity in a transient transcriptional activation analysis using rice protoplasts. It is possible that OsDREB2B requires a modification for full activation in rice plants. Now we analyze the accumulation level of the OsDREB2B proteins in transgenic rice.
