INVESTIGADORES
GONZALEZ SCHAIN Nahuel Damian
artículos
Título:
Phytochrome-imposed oscillations in PIF3 protein abundance regulate hypocotyl growth under diurnal light/dark conditions in Arabidopsis
Autor/es:
SOY J; LEIVAR P; GONZÁLEZ SCHAIN N; SENTANDREU M; PRAT S; QUAIL PH; MONTE E
Revista:
PLANT JOURNAL
Editorial:
WILEY-BLACKWELL PUBLISHING, INC
Referencias:
Lugar: Londres; Año: 2012 vol. 71 p. 390 - 401
ISSN:
0960-7412
Resumen:
Arabidopsis seedlings display rhythmic growth when grown under diurnal
conditions, with maximal elongation rates occurring at the end of the
night under short-day photoperiods. Current evidence indicates that this
behavior involves the action of the growth-promoting bHLH factors
PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) and PHYTOCHROME-INTERACTING
FACTOR 5 (PIF5) at the end of the night, through a coincidence mechanism
that combines their transcriptional regulation by the circadian clock
with control of protein accumulation by light. To assess the possible
role of PIF3 in this process, we have analyzed hypocotyl responses and
marker gene expression in pif single- and higher-order mutants.
The data show that PIF3 plays a prominent role as a promoter of
seedling growth under diurnal light/dark conditions, in conjunction with
PIF4 and PIF5. In addition, we provide evidence that PIF3 functions in
this process through its intrinsic transcriptional regulatory activity,
at least in part by directly targeting growth-related genes, and
independently of its ability to regulate phytochrome B (phyB) levels.
Furthermore, in sharp contrast to PIF4 and PIF5, our data show that the PIF3
gene is not subject to transcriptional regulation by the clock, but
that PIF3 protein abundance oscillates under diurnal conditions as a
result of a progressive decline in PIF3 protein degradation mediated by
photoactivated phyB, and consequent accumulation of the bHLH factor
during the dark period. Collectively, the data suggest that
phyB-mediated, post-translational regulation allows PIF3 accumulation to
peak just before dawn, at which time it accelerates hypocotyl growth,
together with PIF4 and PIF5, by directly regulating the induction of
growth-related genes.