phot1 Inhibition of ABCB19 Primes Lateral Auxin Fluxes in the Shoot Apex Required For Phototropism

Christie, John M.; Yang, Haibing; Richter, Gregory L.; Sullivan, Stuart; Thomson, C.; Lin, Ji; Titapiwatanakun, Boosaree; Ennis, Margaret; Kaiserli, Eirini; Lee, Ok Ran; Adamec, Jiřı́; Peer, Wendy Ann; Murphy, Angus S.

doi:10.1371/journal.pbio.1001076

Cited by 226 publications

(305 citation statements)

References 46 publications

(94 reference statements)

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“…This result implied that some other auxin transporters might be involved in BL-induced auxin transport besides PIN2. The ABC subfamily B auxin transporter could be a potential candidate because the pgp19 mutant has a significantly increased root phototropic bending response after 13 h of unilateral BL illumination (see Supplemental Figure 6 online), coincident with early reports on hypocotyl phototropism (Noh et al, 2003;Christie et al, 2011). Considering that the unilateral BL illumination increased asymmetric GFP expression in DR5 pro :GFP transformed wild-type lines in the root apex transition zone, we conclude that unilateral BL stimulates asymmetric auxin distribution between the shaded and illuminated side by asymmetrically increasing the upward (shootward) polar auxin transport.…”

Section: Discussionsupporting

confidence: 66%

The Signal Transducer NPH3 Integrates the Phototropin1 Photosensor with PIN2-Based Polar Auxin Transport in Arabidopsis Root Phototropism

et al. 2012

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Under blue light (BL) illumination, Arabidopsis thaliana roots grow away from the light source, showing a negative phototropic response. However, the mechanism of root phototropism is still unclear. Using a noninvasive microelectrode system, we showed that the BL sensor phototropin1 (phot1), the signal transducer NONPHOTOTROPIC HYPOCOTYL3 (NPH3), and the auxin efflux transporter PIN2 were essential for BL-induced auxin flux in the root apex transition zone. We also found that PIN2-green fluorescent protein (GFP) localized to vacuole-like compartments (VLCs) in dark-grown root epidermal and cortical cells, and phot1/NPH3 mediated a BL-initiated pathway that caused PIN2 redistribution to the plasma membrane. When dark-grown roots were exposed to brefeldin A (BFA), PIN2-GFP remained in VLCs in darkness, and BL caused PIN2-GFP disappearance from VLCs and induced PIN2-GFP-FM4-64 colocalization within enlarged compartments. In the nph3 mutant, both dark and BL BFA treatments caused the disappearance of PIN2-GFP from VLCs. However, in the phot1 mutant, PIN2-GFP remained within VLCs under both dark and BL BFA treatments, suggesting that phot1 and NPH3 play different roles in PIN2 localization. In conclusion, BL-induced root phototropism is based on the phot1/NPH3 signaling pathway, which stimulates the shootward auxin flux by modifying the subcellular targeting of PIN2 in the root apex transition zone.

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Section: Discussionsupporting

confidence: 66%

The Signal Transducer NPH3 Integrates the Phototropin1 Photosensor with PIN2-Based Polar Auxin Transport in Arabidopsis Root Phototropism

et al. 2012

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“…However, NBD-auxins were less accumulated in the deeper cell layers or in the central cylinder (SI Appendix, Fig. S13 C and D), although the DR5 reporter signal was shown in both the epidermal cells and the central cylinder (31). To confirm that the NBD-auxin distribution mimics the auxin gradient in other plant species, the distribution of NBD-NAA was observed in rice roots.…”

Section: Fluorescent Auxin Distribution Mimics Native Auxin Accumulatmentioning

confidence: 85%

Auxin transport sites are visualized in planta using fluorescent auxin analogs

Hayashi

Nakamura

Fukunaga

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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The plant hormone auxin is a key morphogenetic signal that controls many aspects of plant growth and development. Cellular auxin levels are coordinately regulated by multiple processes, including auxin biosynthesis and the polar transport and metabolic pathways. The auxin concentration gradient determines plant organ positioning and growth responses to environmental cues. Auxin transport systems play crucial roles in the spatiotemporal regulation of the auxin gradient. This auxin gradient has been analyzed using SCF-type E3 ubiquitin-ligase complex-based auxin biosensors in synthetic auxin-responsive reporter lines. However, the contributions of auxin biosynthesis and metabolism to the auxin gradient have been largely elusive. Additionally, the available information on subcellular auxin localization is still limited. Here we designed fluorescently labeled auxin analogs that remain active for auxin transport but are inactive for auxin signaling and metabolism. Fluorescent auxin analogs enable the selective visualization of the distribution of auxin by the auxin transport system. Together with auxin biosynthesis inhibitors and an auxin biosensor, these analogs indicated a substantial contribution of local auxin biosynthesis to the formation of auxin maxima at the root apex. Moreover, fluorescent auxin analogs mainly localized to the endoplasmic reticulum in cultured cells and roots, implying the presence of a subcellular auxin gradient in the cells. Our work not only provides a useful tool for the plant chemical biology field but also demonstrates a new strategy for imaging the distribution of smallmolecule hormones.auxin transporter | subcellular localization

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“…Two potential substrates for phototropin kinase that are involved in phototropism have been identified, namely the auxin efflux transporter ATP-binding cassette B19 (ref. 29) and phytochrome kinase substrate 4 (ref. 30).…”

Section: Discussionmentioning

confidence: 99%

Phosphorylation of BLUS1 kinase by phototropins is a primary step in stomatal opening

et al. 2013

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Opening of stomata in the plant facilitates photosynthetic CO 2 fixation and transpiration. Blue-light perception by phototropins (phot1, phot2) activates the plasma membrane H þ -ATPase, causing stomata to open. Here we describe a regulator that connects these components, a Ser/Thr protein kinase, BLUS1 (BLUE LIGHT SIGNALING1), which mediates a primary step for phototropin signalling in guard cells. blus1 mutants identified by infrared thermography result in a loss of blue light-dependent stomatal opening. BLUS1 encodes a protein kinase that is directly phosphorylated by phot1 in vitro and in vivo at Ser-348 within its C-terminus. Both phosphorylation of Ser-348 and BLUS1 kinase activity are essential for activation of the H þ -ATPase. blus1 mutants show lower stomatal conductance and CO 2 assimilation than wild-type plants under decreased ambient CO 2 . Together, our analyses demonstrate that BLUS1 functions as a phototropin substrate and primary regulator of stomatal control to enhance photosynthetic CO 2 assimilation under natural light conditions.

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phot1 Inhibition of ABCB19 Primes Lateral Auxin Fluxes in the Shoot Apex Required For Phototropism

Cited by 226 publications

References 46 publications

The Signal Transducer NPH3 Integrates the Phototropin1 Photosensor with PIN2-Based Polar Auxin Transport in Arabidopsis Root Phototropism

The Signal Transducer NPH3 Integrates the Phototropin1 Photosensor with PIN2-Based Polar Auxin Transport in Arabidopsis Root Phototropism

Auxin transport sites are visualized in planta using fluorescent auxin analogs

Phosphorylation of BLUS1 kinase by phototropins is a primary step in stomatal opening

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