A Chilling Discovery About Rice

A research group in China has revealed a signaling pathway that allows rice plants to tolerate low temperatures.

AsianScientist (Jan. 3, 2018) – Scientists in China have detailed the mechanism for cold tolerance in rice. They published their findings in the journal Developmental Cell.

The geographical distribution and growing season of plants is determined by their ability to tolerate cold stress. Local temperature anomalies caused by global climate change directly threaten crop production, hence it is essential to obtain a better understanding of how plants withstand the cold.

In this study, a team of researchers led by Professor Chong Kang from the Institute of Botany of the Chinese Academy of Sciences has discovered a mechanism for cold tolerance in rice. They identified the protein OsbHLH002, one of more than 100 members of the bHLH transcription factor family in rice, as a core member in the signaling pathway that protects rice plants against the cold.

In response to low temperatures, the cold-activated protein kinase OsMAPK3 adds a phosphate group to OsbHLH002, thus enhancing the latter’s activity and elevating the downstream expression of elements that help rice plants resist the cold.

OsbHLH002 effectively activated the expression of an enzyme that hydrolyses trehalose-6-phosphate, a modified sugar in plant cells, into trehalose. The higher levels of trehalose serve as antifreeze, preventing the rice plant from freezing.

Moreover, OsMAPK3 attenuated the interaction between OsbHLH002 and the E3 ubiquitin ligase OsHOS1. Ubiquitin ligase tags proteins in cells and marks them for degradation. Hence, by attenuating the interaction between OsbHLH002 and OsHOS1, OsMAPK3 indirectly promotes the production of cold-resistant genes. Collectively, the OsMAPK3-OsbHLH002-OsTPP1 pathway is a major mechanism of cold tolerance in rice.

The article can be found at: Zhang et al. (2017) OsMAPK3 Phosphorylates OsbHLH002/OsICE1 and Inhibits Its Ubiquitination to Activate OsTPP1 and Enhances Rice Chilling Tolerance.


Source: Chinese Academy of Sciences; Photo: Shutterstock.
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