Prof. Chong Kang and team from the Chinese Academy of Sciences (CAS)
reported a new mechanism for chilling tolerance in rice. The findings are
reported in Developmental Cell.
In 2009, the research team had shown that overexpression of the wild rice
gene OrbHLH2 improved tolerance to osmotic stress in Arabidopsis. In their
recent study, they discovered that the cold-activated protein kinase OsMAPK3
phosphorylates the transcription factor OsbHLH002/OsICE1 directly to enhance
its transactivation activity. Furthermore, OsMAPK3 weakened the interaction
between OsbHLH002 and E3 ubiquitin ligase OsHOS1, which led to decreased
ubiquitination and degradation of OsbHLH002.
The boost in protein content and transactivation activity of OsbHLH002
turned on the expression of OsTPP1 (encoding trehalose-6-phosphatase) to
bring about the hydrolysis of trehalose-6-phosphate, increasing the
trehalose content and improving the chilling tolerance of rice.