Disease relevance of PIF4

• Here, we report the identification of a new mutant Arabidopsis locus, srl2 (short under red-light 2), which confers selective hypersensitivity to continuous red, but not far-red, light [1].

High impact information on PIF4

• PIF4, a phytochrome-interacting bHLH factor, functions as a negative regulator of phytochrome B signaling in Arabidopsis [1].
• Consistent with this proposal, PIF4 localizes to the nucleus and can bind to a G-box DNA sequence motif found in various light-regulated promoters [1].
• Despite its hypersensitive morphological phenotype, the srl2 mutant displays no perturbation of light-induced expression of marker genes for chloroplast development [1].
• PIF4 appears to specifically mediate SHB1 regulation of hypocotyl elongation and CHLOROPHYLL a/b BINDING PROTEIN3 or CHALCONE SYNTHASE expression under red light [2].
• Thus, the roles of HRB1 and PIF4 together in regulating both red and blue light responses may represent points where red light signaling and blue light signaling intersect [3].

Other interactions of PIF4

• Among them, it was found that the expressions of PIF4 and PIL6 were regulated in a circadian-dependent manner, exhibiting free-running robust rhythms [4].
• The light-induced expressions of PIF4 and PIL6 were severely impaired in APRR1-ox transgenic lines [4].
• We provide evidence from yeast two-hybrid and in vitro binding assays that two related phytochrome-interacting members in the Arabidopsis family, PIF3 and PIF4, can form both homodimers and heterodimers and that all three dimeric configurations can bind specifically to the G-box DNA sequence motif CACGTG [5].

References