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- Title
A cytosol-tethered YHB variant of phytochrome B retains photomorphogenic signaling activity.
- Authors
Hu, Wei; Lagarias, J. Clark
- Abstract
The red and far-red light photoreceptor phytochrome B (phyB) transmits light signals following cytosol-to-nuclear translocation to regulate transcriptional networks therein. This necessitates changes in protein–protein interactions of phyB in the cytosol, about which little is presently known. Via introduction of a nucleus-excluding G767R mutation into the dominant, constitutively active phyBY276H (YHB) allele, we explore the functional consequences of expressing a cytosol-localized YHBG767R variant in transgenic Arabidopsis seedlings. We show that YHBG767R elicits selective constitutive photomorphogenic phenotypes in dark-grown phyABCDE null mutants, wild type and other phy-deficient genotypes. These responses include light-independent apical hook opening, cotyledon unfolding, seed germination and agravitropic hypocotyl growth with minimal suppression of hypocotyl elongation. Such phenotypes correlate with reduced PIF3 levels, which implicates cytosolic targeting of PIF3 turnover or PIF3 translational inhibition by YHBG767R. However, as expected for a cytoplasm-tethered phyB, YHBG767R elicits reduced light-mediated signaling activity compared with similarly expressed wild-type phyB in phyABCDE mutant backgrounds. YHBG767R also interferes with wild-type phyB light signaling, presumably by formation of cytosol-retained and/or otherwise inactivated heterodimers. Our results suggest that cytosolic interactions with PIFs play an important role in phyB signaling even under physiological conditions. Key message: Cytoplasmic phytochrome B activity is revealed by expression of a cytosol-tethered, constitutively active YHBG767R mutant allele.
- Subjects
PHYTOCHROMES; GENE regulatory networks; PLANT photoreceptors; PROTEIN-protein interactions; PHENOTYPES; GERMINATION; COTYLEDONS; CYTOSOL
- Publication
Plant Molecular Biology, 2024, Vol 114, Issue 4, p1
- ISSN
0167-4412
- Publication type
Article
- DOI
10.1007/s11103-024-01469-2