Understanding how transcription factor DREB2A gives plants drought and heat tolerance


September 19, 2017

Will assist development of drought- and heat-tolerant crops

The transcription factor DREB2A helps impart drought and heat tolerance in plants. RIKEN CSRS researchers, in collaborative work with the University of Tokyo and Japan International Research Center for Agricultural Sciences (JIRCA), have succeeded in elucidating DREB2A's activation mechanism.

DREB2A itself does not exhibit activity. Rather, it is converted to a stable, activated form called DREB2A CA, which is made from DREB2A through the deletion of a sequence of 30 amino acids in its center known as the negative regulatory domain (NRD). Although the introduction of DREB2A CA into plants was known to enhance drought and heat stress tolerance, the molecular mechanism that triggers this activity had remained elusive for more than 10 years.

In this study, researchers found that the degradation enzyme BPM-CUL3 E3 ligase recognizes NRD and binds to it, and the binding triggers the DREB2A degradation mechanism. Since DREB2A CA does not have NRD, it is neither recognized nor degraded by BPM-CUL3 E3 ligase and remains stable. Thus, the removal of NRD stabilizes and activates DREB2A CA. In plants, this suggests a mechanism in which NRD may be masked in times of stress, specifically by modifications such as phosphorylation or by an unknown protein.

This research aids in propelling understanding of plants' abilities to acquire tolerance to stresses such as high temperatures and dry conditions. It will also be useful in the development of crops with improved tolerance to such stresses.

Original article
Proc. Natl. Acad. Sci. USA doi:10.1073/pnas.1704189114
K. Morimoto, N. Ohama, S. Kidokoro, J. Mizoi, F. Takahashi, D. Todaka, J. Mogami, H. Sato, F. Qin, J.- S. Kim, Y. Fukao, M. Fujiwara, K. Shinozaki, K. Yamaguchi-Shinozaki,
"BPM-CUL3 E3 ligase modulates thermotolerance by facilitating negative regulatory domainmediated degradation of DREB2A in Arabidopsis".
Kazuo Shinozaki
Group Director
Gene Discovery Research Group