PMID:24569844

Citation	Li, Y, Jing, Y, Li, J, Xu, G and Lin, R' (2014) Arabidopsis VQ-motif-containing Protein 29 Represses Seedling De-etiolation by Interacting with PIF1. Plant Physiol. '
Abstract	Seedling de-etiolation, a critical process in early plant development, is regulated by an intricate transcriptional network. Here, we identified VQ motif-containing protein 29 (VQ29) as a novel regulator of the photomorphogenic response in Arabidopsis thaliana. We showed that 29 of the 34 VQ proteins present in Arabidopsis exhibit transcriptional activity in plant cells, and that mutations in the VQ motif affect the transcriptional activity of VQ29. We then functionally characterized VQ29 and showed that the hypocotyl growth of plants overexpressing VQ29 is hyposensitive to far-red and low intensity white light, whereas a vq29 loss-of-function mutant exhibits decreased hypocotyl elongation under low intensity of far-red light or white light. Consistent with this, VQ29 expression is repressed by light in a phytochrome-dependent manner. Intriguingly, our yeast two-hybrid, bimolecular fluorescence complementation and co-immunoprecipitation assays showed that VQ29 physically interacts with PHYTOCHROME-INTERACTING FACTOR1 (PIF1). We then showed that VQ29 and PIF1 directly bind to the promoter of a cell elongation-related gene, XYLOGLUCAN ENDOTRANSGLYCOSYLASE7, and co-activate its expression. Furthermore, the vq29 pif1 double mutant has shorter hypocotyls than either of the corresponding single mutants. Therefore, our study reveals that VQ29 is a negative transcriptional regulator of light-mediated inhibition of hypocotyl elongation that likely promotes the transcriptional activity of PIF1 during early seedling development.
Links	PubMed Online version:10.1104/pp.113.234492
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ARATH:Q8LE89		GO:0009704: de-etiolation	ECO:0000315:		P		VQ29 is shown to be a repressor of de-etiolation in Figure 2. Mutants overexpressing VQ29 showed reduced sensitivity to far-red and low light conditions, showing that in these conditions, VQ29 may have been inhibiting de-etiolation processes. This observation is further solidified in Figure 2D.	complete CACAO 9912
ARATH:Q8LE89		GO:0003712: transcription cofactor activity	ECO:0000314:		F		Figure 1 illustrates that members of the VQ family, in this study particularly, VQ29, have transcriptional activity according to the results of a heterologous gene reporter system protocol.	complete CACAO 9909

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