Tangent algorithm for photogravitropic balance in plants and Phycomyces blakesleeanus: Roles for EHB1 and NPH3 of Arabidopsis thaliana
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2021
Authors
Duemmer, MichaelaSpasić, Slađana

Feil, Martin
Michalski, Christian
Forreiter, Christoph
Galland, Paul
Article (Published version)

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Plant organs that are exposed to continuous unilateral light reach in the steady-state a photogravitropic bending angle that results from the mutual antagonism between the photo- and gravitropic responses. To characterize the interaction between the two tropisms and their quantitative relationship we irradiated seedlings of Arabidopsis thaliana that were inclined at various angles and determined the fluence rates of unilateral blue light required to compensate the gravitropism of the inclined hypocotyls. We found the compensating fluence rates to increase with the tangent of the inclination angles (0? lt ? lt 90? or max. 120?) and decrease with the cotangent (90? lt ? lt 180? or max. 120?of the inclination angles. The tangent dependence became also evident from analysis of previous data obtained with Avena sativa and the phycomycete fungus, Phycomyces blakesleeanus. By using loss-of function mutant lines of Arabidopsis, we identified EHB1 (enhanced bending 1) as an essential ele...ment for the generation of the tangent and cotangent relationships. Because EHB1 possesses a C2-domain with two putative calcium binding sites, we propose that the ubiquitous calcium dependence of gravi- and phototropism is in part mediated by Ca2+-bound EHB1. Based on a yeast-two-hybrid analysis we found evidence that EHB1 does physically interact with the ARF-GAP protein AGD12. Both proteins were reported to affect gravi- and phototropism antagonistically. We further showed that only AGD12, but not EHB1, interacts with its corresponding ARF-protein. Evidence is provided that AGD12 is able to form homodimers as well as heterodimers with EHB1. On the basis of these data we present a model for a mechanism of early tropism events, in which Ca2+-activated EHB1 emerges as the central processor-like element that links the gravi- and phototropic transduction chains and that generates in coordination with NPH3 and AGD12 the tangent / cotangent algorithm governing photogravitropic equilibrium.
Keywords:
Yeast-two hybrid analysis / Tangent relationship / Phototropism / Photogravitropic equilibrium / Hypocotyl / Gravitropism / EHB1 / Calcium / Arabidopsis / AGD12Source:
Journal of Plant Physiology, 2021, 260Publisher:
- Elsevier Gmbh, Munich
Funding / projects:
- DLR/BMWiHelmholtz AssociationGerman Aerospace Centre (DLR)Federal Ministry for Economic Affairs and Energy (BMWi) [50WB1025, 50WB1325, 50WB1814]
- Ministry of Education, Science and Technological Development, Republic of Serbia, Grant no. 200053 (University of Belgrade, Institute for Multidisciplinary Research) (RS-200053)
DOI: 10.1016/j.jplph.2021.153396
ISSN: 0176-1617
PubMed: 33713940
WoS: 000642485200005
Scopus: 2-s2.0-85102605268
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Institut za multidisciplinarna istraživanjaTY - JOUR AU - Duemmer, Michaela AU - Spasić, Slađana AU - Feil, Martin AU - Michalski, Christian AU - Forreiter, Christoph AU - Galland, Paul PY - 2021 UR - http://rimsi.imsi.bg.ac.rs/handle/123456789/1453 AB - Plant organs that are exposed to continuous unilateral light reach in the steady-state a photogravitropic bending angle that results from the mutual antagonism between the photo- and gravitropic responses. To characterize the interaction between the two tropisms and their quantitative relationship we irradiated seedlings of Arabidopsis thaliana that were inclined at various angles and determined the fluence rates of unilateral blue light required to compensate the gravitropism of the inclined hypocotyls. We found the compensating fluence rates to increase with the tangent of the inclination angles (0? lt ? lt 90? or max. 120?) and decrease with the cotangent (90? lt ? lt 180? or max. 120?of the inclination angles. The tangent dependence became also evident from analysis of previous data obtained with Avena sativa and the phycomycete fungus, Phycomyces blakesleeanus. By using loss-of function mutant lines of Arabidopsis, we identified EHB1 (enhanced bending 1) as an essential element for the generation of the tangent and cotangent relationships. Because EHB1 possesses a C2-domain with two putative calcium binding sites, we propose that the ubiquitous calcium dependence of gravi- and phototropism is in part mediated by Ca2+-bound EHB1. Based on a yeast-two-hybrid analysis we found evidence that EHB1 does physically interact with the ARF-GAP protein AGD12. Both proteins were reported to affect gravi- and phototropism antagonistically. We further showed that only AGD12, but not EHB1, interacts with its corresponding ARF-protein. Evidence is provided that AGD12 is able to form homodimers as well as heterodimers with EHB1. On the basis of these data we present a model for a mechanism of early tropism events, in which Ca2+-activated EHB1 emerges as the central processor-like element that links the gravi- and phototropic transduction chains and that generates in coordination with NPH3 and AGD12 the tangent / cotangent algorithm governing photogravitropic equilibrium. PB - Elsevier Gmbh, Munich T2 - Journal of Plant Physiology T1 - Tangent algorithm for photogravitropic balance in plants and Phycomyces blakesleeanus: Roles for EHB1 and NPH3 of Arabidopsis thaliana VL - 260 DO - 10.1016/j.jplph.2021.153396 ER -
@article{ author = "Duemmer, Michaela and Spasić, Slađana and Feil, Martin and Michalski, Christian and Forreiter, Christoph and Galland, Paul", year = "2021", abstract = "Plant organs that are exposed to continuous unilateral light reach in the steady-state a photogravitropic bending angle that results from the mutual antagonism between the photo- and gravitropic responses. To characterize the interaction between the two tropisms and their quantitative relationship we irradiated seedlings of Arabidopsis thaliana that were inclined at various angles and determined the fluence rates of unilateral blue light required to compensate the gravitropism of the inclined hypocotyls. We found the compensating fluence rates to increase with the tangent of the inclination angles (0? lt ? lt 90? or max. 120?) and decrease with the cotangent (90? lt ? lt 180? or max. 120?of the inclination angles. The tangent dependence became also evident from analysis of previous data obtained with Avena sativa and the phycomycete fungus, Phycomyces blakesleeanus. By using loss-of function mutant lines of Arabidopsis, we identified EHB1 (enhanced bending 1) as an essential element for the generation of the tangent and cotangent relationships. Because EHB1 possesses a C2-domain with two putative calcium binding sites, we propose that the ubiquitous calcium dependence of gravi- and phototropism is in part mediated by Ca2+-bound EHB1. Based on a yeast-two-hybrid analysis we found evidence that EHB1 does physically interact with the ARF-GAP protein AGD12. Both proteins were reported to affect gravi- and phototropism antagonistically. We further showed that only AGD12, but not EHB1, interacts with its corresponding ARF-protein. Evidence is provided that AGD12 is able to form homodimers as well as heterodimers with EHB1. On the basis of these data we present a model for a mechanism of early tropism events, in which Ca2+-activated EHB1 emerges as the central processor-like element that links the gravi- and phototropic transduction chains and that generates in coordination with NPH3 and AGD12 the tangent / cotangent algorithm governing photogravitropic equilibrium.", publisher = "Elsevier Gmbh, Munich", journal = "Journal of Plant Physiology", title = "Tangent algorithm for photogravitropic balance in plants and Phycomyces blakesleeanus: Roles for EHB1 and NPH3 of Arabidopsis thaliana", volume = "260", doi = "10.1016/j.jplph.2021.153396" }
Duemmer, M., Spasić, S., Feil, M., Michalski, C., Forreiter, C.,& Galland, P.. (2021). Tangent algorithm for photogravitropic balance in plants and Phycomyces blakesleeanus: Roles for EHB1 and NPH3 of Arabidopsis thaliana. in Journal of Plant Physiology Elsevier Gmbh, Munich., 260. https://doi.org/10.1016/j.jplph.2021.153396
Duemmer M, Spasić S, Feil M, Michalski C, Forreiter C, Galland P. Tangent algorithm for photogravitropic balance in plants and Phycomyces blakesleeanus: Roles for EHB1 and NPH3 of Arabidopsis thaliana. in Journal of Plant Physiology. 2021;260. doi:10.1016/j.jplph.2021.153396 .
Duemmer, Michaela, Spasić, Slađana, Feil, Martin, Michalski, Christian, Forreiter, Christoph, Galland, Paul, "Tangent algorithm for photogravitropic balance in plants and Phycomyces blakesleeanus: Roles for EHB1 and NPH3 of Arabidopsis thaliana" in Journal of Plant Physiology, 260 (2021), https://doi.org/10.1016/j.jplph.2021.153396 . .