PT  - JOURNAL ARTICLE
AU  - Jishan Jiang
AU  - Yanmei Xiao
AU  - Wei Hu
AU  - Hao Chen
AU  - Liping Zeng
AU  - Haiyan Ke
AU  - Franck A. Ditengou
AU  - Upendra Devisetty
AU  - Klaus Palme
AU  - Julin Maloof
AU  - Katayoon Dehesh
TI  - Retrograde induction of phyB orchestrates ethylene-auxin hierarchy to regulate growth
AID  - 10.1101/2020.01.31.929133
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.01.31.929133
4099  - http://biorxiv.org/content/early/2020/02/02/2020.01.31.929133.short
4100  - http://biorxiv.org/content/early/2020/02/02/2020.01.31.929133.full
AB  - Exquisitely regulated plastid-to-nucleus communication by retrograde signaling pathways is essential for fine-tuning of responses to the prevailing environmental conditions. The plastidial retrograde signaling metabolite methylerythritol cyclodiphosphate (MEcPP) has emerged as a stress signal transduced into a diverse ensemble of response outputs. Here we demonstrate enhanced phytochrome B protein abundance in red-light grown MEcPP-accumulating mutant (ceh1) plant relative to wild-type seedlings. We further establish MEcPP-mediated coordination of phytochrome B with auxin and ethylene signaling pathways, and uncover differential hypocotyl growth of red-light grown seedlings in response to these phytohormones. Genetic and pharmacological interference with ethylene and auxin pathways outline the hierarchy of responses, placing auxin epistatic to the ethylene signaling pathway. Collectively, our finding establishes the key role of a plastidial retrograde metabolite in orchestrating the transduction of a repertoire of signaling cascades, and positions plastids at the zenith of relaying information coordinating external signals and internal regulatory circuitry to secure organismal integrity.Two sentence summary The plastidial retrograde metabolite, MEcPP, orchestrates coordination of light and hormonal signaling cascade through induction of phytochrome B abundance and modulation of auxin and ethylene levels for optimal adaptive responses to light environment.