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GrainGenes Reference Report: PPS-129-1127

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Reference	PPS-129-1127
Title	The serine-rich N-terminal domain of oat phytochrome a helps regulate light responses and subnuclear localization of the photoreceptor
Journal	Plant Physiology
Year	2002
Volume	129
Pages	1127-1137
Author	Casal JJ [ Show all 10 ]
Abstract	Summary: Phytochrome (phy) A mediates two distinct photobiological responses in plants: the very-low-fluence response (VLFR), which can be saturated by short pulses of very-low-fluence light, and the high-irradiance response (HIR), which requires prolonged irradiation with higher fluences of far-red light (FR). To investigate whether the VLFR and HIR involve different domains within the phyA molecule, transgenic tobacco (Nicotiana tabacum cv Xanthi) and Arabidopsis seedlings expressing full-length (FL) and various deletion mutants of oat (Avena sativa) phyA were examined for their light sensitivity. Although most mutants were either partially active or inactive, a strong differential effect was observed for the delta 6-12 phyA mutant missing the serine-rich domain between amino acids 6 and 12. delta 6-12 phyA was as active as FL phyA for the VLFR of hypocotyl growth and cotyledon unfolding in Arabidopsis, and was hyperactive in the VLFR of hypocotyl growth and cotyledon unfolding in tobacco, and the VLFR blocking subsequent greening under white light in Arabidopsis. In contrast, delta 6-12 phyA showed a dominant-negative suppression of HIR in both species. In hypocotyl cells of Arabidopsis irradiated with FR phyA:green fluorescent protein (GFP) and delta 6-12 phyA:GFP fusions localized to the nucleus and coalesced into foci. The proportion of nuclei with abundant foci was enhanced by continuous compared with hourly FR provided at equal total fluence in FL phyA:GFP, and by delta 6-12 phyA mutation under hourly FR. We propose that the N-terminal serine-rich domain of phyA is involved in channeling downstream signaling via the VLFR or HIR pathways in different cellular contexts
Keyword	[ Hide all but 1 of 51 ] anthocyanins arabidopsis arabidopsis thaliana avena avena sativa biochemical pathways biosynthesis cell cotyledons deletion downstream far red light fluorescent protein food crops fusion gfp greening growth hypocotyls irradiation localization mediate molecule mutation n-terminal domain nicotiana nuclei nucleus oat oat phytochrome photoreceptors phytochrome plant composition plant development plant morphology protein pulse recombinant proteins reporter gene responses seedling sensitivity signal signaling suppression tobacco transgenic transgenic plant transgenic tobacco translocation white light

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