TY - JOUR
T1 - Phytochrome-imposed inhibition of PIF7 activity shapes photoperiodic growth in Arabidopsis together with PIF1, 3, 4 and 5
AU - Leivar, Pablo
AU - Martín, Guiomar
AU - Soy, Judit
AU - Dalton-Roesler, Jutta
AU - Quail, Peter H.
AU - Monte, Elena
N1 - Funding Information:
We thank M. Cohn and C. Coates for early work on the project, and J. Chory, Ullas Pedmale and L. Li for PIF7-flash lines. This work was supported by Marie Curie International Reintegration Grant PIRG06-GA-2009-256420 and by funds from Universitat Ramon Llull/Obra Social la Caixa (2016-URL-Internac-019, 2018-LC-05 and 2018-URL-IR2nQ-019) to P.L., by NIH (5R01GM047475-24) and USDA ARS Current Research Information System (2030-21000-051-00D) grants to P.H.Q., and by grants from the Spanish ‘Ministerio de Economía y Competitividad’ (MINECO) (BIO2012-31672 and BIO2015-68460-P), by FEDER / Ministerio de Ciencia, Innovación y Universidades – Agencia Estatal de Investigación (Project Reference BIO2015-68460-P) and from the CERCA Programme/Generalitat de Catalunya (Project References 2014-SGR-1406 and 2017SGR-718) to E.M. We acknowledge financial support by the CERCA Programme/Generalitat de Catalunya and from MINECO through the ‘Severo Ochoa Programme for Centers of Excellence in R&D’ 2016-2019 (SEV-2015-0533).
Funding Information:
We thank M. Cohn and C. Coates for early work on the project, and J. Chory, Ullas Pedmale and L. Li for PIF7‐flash lines. This work was supported by Marie Curie International Reintegration Grant PIRG06‐GA‐2009‐256420 and by funds from Universitat Ramon Llull/Obra Social la Caixa (2016‐URL‐Internac‐019, 2018‐LC‐05 and 2018‐URL‐IR2nQ‐019) to P.L., by NIH (5R01GM047475‐24) and USDA ARS Current Research Information System (2030‐21000‐051‐00D) grants to P.H.Q., and by grants from the Spanish ‘Ministerio de Economía y Competitividad’ (MINECO) (BIO2012‐31672 and BIO2015‐68460‐P), by FEDER / Ministerio de Ciencia, Innovación y Universidades – Agencia Estatal de Investigación (Project Reference BIO2015‐68460‐P) and from the CERCA Programme/Generalitat de Catalunya (Project References 2014‐SGR‐1406 and 2017SGR‐718) to E.M. We acknowledge financial support by the CERCA Programme/Generalitat de Catalunya and from MINECO through the ‘Severo Ochoa Programme for Centers of Excellence in R&D’ 2016‐2019 (SEV‐2015‐0533).
Publisher Copyright:
© 2020 Scandinavian Plant Physiology Society
PY - 2020/7/1
Y1 - 2020/7/1
N2 - Under photoperiodic conditions, Arabidopsis thaliana seedling growth is inhibited in long days (LDs), but promoted under the extended nights of short days (SDs). This behavior is partly implemented by phytochrome (phy)-imposed oscillations in the abundance of the growth-promoting, phy-interacting bHLH transcription factors PHY-INTERACTING FACTOR 1 (PIF1), PIF3, PIF4 and PIF5 (PIF quartet or PIFq). However, the observation that a pifq mutant is still stimulated to elongate when given a phy-inactivating end-of-day far-red pulse (EODFR), suggests that additional factors are involved in the phy-mediated suppression of growth during the subsequent dark period. Here, by combining growth-analysis of pif7 single- and higher-order mutants with gene expression analysis under SD, LD, SD-EODFR, and LD-EODFR, we show that PIF7 promotes growth during the dark hours of SD, by regulating growth-related gene expression. Interestingly, the relative contribution of PIF7 in promoting growth is stronger under EODFR, whereas PIF3 role is more important under SD, suggesting that PIF7 is a prominent target of phy-suppression. Indeed, we show that phy imposes phosphorylation and inactivation of PIF7 during the light hours in SD, and prevents full dephosphorylation during the night. This repression can be lifted with an EODFR, which correlates with increased PIF7-mediated gene expression and elongation. In addition, our results suggest that PIF7 function might involve heterodimerization with PIF3. Furthermore, our data indicate that a pifqpif7 quintuple mutant is largely insensitive to photoperiod for hypocotyl elongation. Collectively, the data suggest that PIF7, together with the PIFq, is required for the photoperiodic regulation of seasonal growth.
AB - Under photoperiodic conditions, Arabidopsis thaliana seedling growth is inhibited in long days (LDs), but promoted under the extended nights of short days (SDs). This behavior is partly implemented by phytochrome (phy)-imposed oscillations in the abundance of the growth-promoting, phy-interacting bHLH transcription factors PHY-INTERACTING FACTOR 1 (PIF1), PIF3, PIF4 and PIF5 (PIF quartet or PIFq). However, the observation that a pifq mutant is still stimulated to elongate when given a phy-inactivating end-of-day far-red pulse (EODFR), suggests that additional factors are involved in the phy-mediated suppression of growth during the subsequent dark period. Here, by combining growth-analysis of pif7 single- and higher-order mutants with gene expression analysis under SD, LD, SD-EODFR, and LD-EODFR, we show that PIF7 promotes growth during the dark hours of SD, by regulating growth-related gene expression. Interestingly, the relative contribution of PIF7 in promoting growth is stronger under EODFR, whereas PIF3 role is more important under SD, suggesting that PIF7 is a prominent target of phy-suppression. Indeed, we show that phy imposes phosphorylation and inactivation of PIF7 during the light hours in SD, and prevents full dephosphorylation during the night. This repression can be lifted with an EODFR, which correlates with increased PIF7-mediated gene expression and elongation. In addition, our results suggest that PIF7 function might involve heterodimerization with PIF3. Furthermore, our data indicate that a pifqpif7 quintuple mutant is largely insensitive to photoperiod for hypocotyl elongation. Collectively, the data suggest that PIF7, together with the PIFq, is required for the photoperiodic regulation of seasonal growth.
UR - http://www.scopus.com/inward/record.url?scp=85087039902&partnerID=8YFLogxK
U2 - 10.1111/ppl.13123
DO - 10.1111/ppl.13123
M3 - Article
C2 - 32412656
AN - SCOPUS:85087039902
SN - 0031-9317
VL - 169
SP - 452
EP - 466
JO - Physiologia Plantarum
JF - Physiologia Plantarum
IS - 3
ER -