SEUSS and PIF4 Coordinately Regulate Light and Temperature Signaling Pathways to Control Plant Growth

Abstract

Plants continuously monitor environmental conditions (such as light and temperature) and adjust their growth and development accordingly. The transcription factor PHYTOCHROME-INTERACTING FACTOR4 (PIF4) regulates both light and temperature signaling pathways. Here, we identified ENHANCED PHOTOMORPHOGENIC2 (EPP2) as a new repressor of photomorphogenesis in red, far-red, and blue light. Map-based cloning revealed that EPP2 encodes the SEUSS (SEU) transcription regulator. The C terminus of SEU has transcriptional activation activity, and SEU physically interacts with PIF4. Moreover, SEU promotes the expression of many genes, including auxin biosynthetic and responsive genes, and regulates IAA levels in plants. SEU associates with the regulatory regions of INDOLE-3-ACETIC ACID INDUCIBLE6 (IAA6) and IAA19 in a PIF4-independent manner, whereas the binding of PIF4 to these genes requires SEU. Furthermore, mutations in SEU affect H3K4me3 methylation at IAA6 and IAA19, and SEU positively regulates warm temperature-mediated hypocotyl growth together with PIF4. Collectively, our results reveal that SEU acts as a central regulator integrating light and temperature signals to control plant growth by coordinating with PIF4.

PHYTOCHROME-INTERACTING FACTOR-LIKE14 and SLENDER RICE1 Interaction Controls Seedling Growth under Salt Stress

“…cv ZH11 and OsPIL14OE (5) seedlings were grown in darkness for 7 d before sampling. RNA sequencing analysis was conducted as previously described with three biological replicates (Huai et al, 2018). Genes with more than 2-fold change in expression and P , 0.05 were considered to be differentially expressed genes.…”

Transcriptional regulatory network of the light signaling pathways

“…PIF4 and the transcriptional co-regulator SEUSS (SEU) interact, and both target auxin signaling genes to regulate warm temperature-mediated hypocotyl growth. However, the binding of SEU to its target genes occurs independently of PIF4 (Huai et al, 2018). How SEU is recruited to its target genes remains unknown.…”

Dark, Light, and Temperature: Key Players in Plant Morphogenesis

“…In addition to stimulating auxin production, PIF4 also directly activates a series of auxin-responsive genes, including SMALL AUXIN UP RNA (SAUR) genes (Franklin et al, 2011), INDOLE-3-ACETIC ACID INDUCIBLE6 (IAA6), IAA19, and IAA29 (Nomoto et al, 2012;Sun et al, 2013;Huai et al, 2018). SAUR proteins physically interact with the D-clade type 2C protein phosphatases to repress their activity, resulting in the phosphorylation and activation of plasma membrane H 1 -ATPases to stimulate cell elongation (Spartz et al, 2014).…”

“…Fourth, in addition to PIF4-centered signaling, some epigenetic-related components also contribute to thermomorphogenesis (Kumar and Wigge, 2010;Zha et al, 2017;Huai et al, 2018;Tasset et al, 2018). The relationships between PIF4 and these players are worthy of pursuit.…”