The Red Light Receptor Phytochrome B Directly Enhances Substrate-E3 Ligase Interactions to Attenuate Ethylene Responses

Publication date: Available online 23 November 2016
Source:Developmental Cell
Author(s): Hui Shi, Xing Shen, Renlu Liu, Chang Xue, Ning Wei, Xing Wang Deng, Shangwei Zhong
Plants germinating under subterranean darkness assume skotomorphogenesis, a developmental program strengthened by ethylene in response to mechanical pressure of soil. Upon reaching the surface, light triggers a dramatic developmental transition termed de-etiolation that requires immediate termination of ethylene responses. Here, we report that light activation of photoreceptor phyB results in rapid degradation of EIN3, the master transcription factor in the ethylene signaling pathway. As a result, light rapidly and efficiently represses ethylene actions. Specifically, phyB directly interacts with EIN3 in a light-dependent manner and also physically associates with F box protein EBFs. The light-activated association of phyB, EIN3, and EBF1/EBF2 proteins stimulates robust EIN3 degradation by SCF^EBF1/EBF2 E3 ligases. We reveal that phyB manipulates substrate-E3 ligase interactions in a light-dependent manner, thus directly controlling the stability of EIN3. Our findings illustrate a mechanistic model of how plants transduce light information to immediately turn off ethylene signaling for de-etiolation initiation.

Graphical abstract

Teaser

Exposure of plants to sunshine upon emergence from the soil causes dramatic developmental changes, including inhibition of ethylene signaling. Shi, Shen et al. now show that the light-activated photoreceptor phyB contributes to this acute transition by mediating an interaction between the ethylene signaling regulator EIN3 and an E3 ubiquitin ligase.


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