RCB initiates Arabidopsis thermomorphogenesis by stabilizing the thermoregulator PIF4 in the daytime

Qiu, Yongjian; Pasoreck, Elise K.; Yoo, Chan Yul; He, Jiangman; Wang, He; Bajracharya, Abhishesh; Li, Meina; Larsen, Haley D; Cheung, Stacey T. M.; Meng, Chen

doi:10.1038/s41467-021-22313-x

Cited by 41 publications

(40 citation statements)

References 79 publications

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“…Transcriptional regulation of thermoresponsive genes is one of the earliest and principal steps in plant thermomorphogenesis. We previously discovered that PIF4 and its coactivator HMR promote thermomorphogenetic hypocotyl growth in the daytime by activating the transcription of key growth-promoting genes (Qiu et al, 2019; Qiu et al, 2021). In this study, we further demonstrate that PIF4/HMR-mediated transcriptional regulation is achieved by recruiting the Mediator complex through their direct interactions with MED14 (Figure 5E).…”

Section: Discussionmentioning

confidence: 99%

PIF4/HEMERA-mediated daytime thermosensory growth requires the Mediator subunit MED14

Qiu

Bajracharya

et al. 2022

Preprint

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While moderately elevated ambient temperatures do not trigger stress responses in plants, they do significantly stimulate the growth of specific organs through a process known as thermomorphogenesis. The basic helix-loop-helix transcription factor PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) plays a central role in regulating thermomorphogenetic hypocotyl elongation in various plant species, including Arabidopsis thaliana. Although it is well known that PIF4 promotes plant thermosensory growth by activating genes involved in the biosynthesis and signaling of the phytohormone auxin, the detailed molecular mechanism of such transcriptional activation is not clear. Our previous studies demonstrated that HEMERA (HMR), a transcriptional co-activator of PIF4, promotes the thermo-induced expression of PIF4 target genes through its nine-amino-acid transactivation domain (9aaTAD). In this report, we investigate the role of the Mediator complex in the PIF4/HMR-mediated thermoresponsive gene expression. Through the characterization of various mutants of the Mediator complex, a tail subunit named MED14 is identified as an essential factor for thermomorphogenetic hypocotyl growth. MED14 is required for the thermal induction of PIF4 target genes but has a marginal effect on the levels of PIF4 and HMR. Further transcriptomic analyses confirm that the expression of numerous PIF4/HMR-dependent, auxin-related genes requires MED14 at warm temperatures. Moreover, PIF4 and HMR physically interact with MED14 and both are indispensable for the association of MED14 with the promoters of these thermoresponsive genes. Taken together, these results unveil an important thermomorphogenetic mechanism, in which PIF4 and HMR recruit the Mediator complex to activate auxin-related growth-promoting genes when plants sense moderate increases in ambient temperature.One-sentence summaryThe Mediator subunit MED14 promotes thermomorphogenesis by interacting with PHYTOCHROME-INTERACTING FACTOR 4 and HEMERA to induce the expression of growth-promoting genes at elevated temperatures.

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Section: Discussionmentioning

confidence: 99%

PIF4/HEMERA-mediated daytime thermosensory growth requires the Mediator subunit MED14

Qiu

Bajracharya

et al. 2022

Preprint

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“…HMR does not regulate PIF4 transcription, but interacts directly with PIF4 and activates the plant growth-related gene expressions and promotes PIF4 accumulation [ 15 ]. REGULATOR OF CHLOROPLAST BIOGENESIS (RCB), which interacts with HMR, acts as a novel temperature signaling component that functions collaboratively with HMR to initiate thermomorphogenesis by selectively stabilizing PIF4 in the daytime [ 101 ]. rcb-101 mutants completely rescue the short-hypocotyl phenotypes of hmr-22 mutants at 27 °C and restore PIF4 stability and activity in hmr-22 .…”

Section: Pif4-interacting Transcriptional Regulatorsmentioning

confidence: 99%

“…In addition, RCB regulates PIF4 stability and activity and is required for thermoresponsive PIF4 accumulation. Therefore, HMR and RCB collaboratively enable thermomorphogenesis via stabilizing PIF4 ( Figure 5 A) [ 101 ].…”

Section: Pif4-interacting Transcriptional Regulatorsmentioning

confidence: 99%

PIF4 and PIF4-Interacting Proteins: At the Nexus of Plant Light, Temperature and Hormone Signal Integrations

Zhu

2021

IJMS

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Basic helix-loop-helix (bHLH) family transcription factor PHYTOCHROME INTERACTING FACTOR 4 (PIF4) is necessary for plant adaption to light or high ambient temperature. PIF4 directly associates with plenty of its target genes and modulates the global transcriptome to induce or reduce gene expression levels. However, PIF4 activity is tightly controlled by its interacting proteins. Until now, twenty-five individual proteins have been reported to physically interact with PIF4. These PIF4-interacting proteins act together with PIF4 and form a unique nexus for plant adaption to light or temperature change. In this review, we will discuss the different categories of PIF4-interacting proteins, including photoreceptors, circadian clock regulators, hormone signaling components, and transcription factors. These distinct PIF4-interacting proteins either integrate light and/or temperature cues with endogenous hormone signaling, or control PIF4 abundances and transcriptional activities. Taken together, PIF4 and PIF4-interacting proteins play major roles for exogenous and endogenous signal integrations, and therefore establish a robust network for plants to cope with their surrounding environmental alterations.

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“…These responses are collectively referred to as thermo-morphogenesis. Therefore, plants that can endure warmer temperatures are highly desirable, and progress has been reported lately [ 17 ]. For instance, in wheat, high temperature adversely affects plant development, productivity, and grain quality [ 18 ].…”

mentioning

confidence: 99%

Crop Improvement: Now and Beyond

Sourdille

Devaux²

2021

Biology

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RCB initiates Arabidopsis thermomorphogenesis by stabilizing the thermoregulator PIF4 in the daytime

Cited by 41 publications

References 79 publications

PIF4/HEMERA-mediated daytime thermosensory growth requires the Mediator subunit MED14

PIF4/HEMERA-mediated daytime thermosensory growth requires the Mediator subunit MED14

PIF4 and PIF4-Interacting Proteins: At the Nexus of Plant Light, Temperature and Hormone Signal Integrations

Crop Improvement: Now and Beyond

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