PIL5, a phytochrome-interacting basic helix-loop-helix protein, is a key negative regulator of seed germination in Arabidopsis thaliana

Eunkyoo Oh, Jonghyun Kim, Eunae Park, Jeong Il Kim, Changwon Kang, Giltsu Choi

Research output: Contribution to journalArticle

258 Citations (Scopus)


The first decision made by an angiosperm seed, whether to germinate or not, is based on integration of various environmental signals such as water and light. The phytochromes (Phys) act as red and far-red light (Pfr) photoreceptors to mediate light signaling through yet uncharacterized pathways. We report here that the PIF3-like 5 (PIL5) protein, a basic helix-loop-helix transcription factor, is a key negative regulator of phytochrome-mediated seed germination. PIL5 preferentially interacts with the Pfr forms of Phytochrome A (PhyA) and Phytochrome B (PhyB). Analyses of a pil5 mutant in conjunction with phyA and phyB mutants, a pif3 pil5 double mutant, and PIL5 overexpression lines indicate that PIL5 is a negative factor in Phy-mediated promotion of seed germination, inhibition of hypocotyl negative gravitropism, and inhibition of hypocotyl elongation. Our data identify PIL5 as the first Phy-interacting protein that regulates seed germination.

Original languageEnglish
Pages (from-to)3045-3058
Number of pages14
JournalPlant Cell
Issue number11
Publication statusPublished - 2004 Nov 1
Externally publishedYes


ASJC Scopus subject areas

  • Plant Science
  • Cell Biology

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