TY  - JOUR
AU  - Živanović, Branka  D.
AU  - Danilović Luković, Jelena
AU  - Korac, Aleksandra
AU  - Stanić, Marina
AU  - Spasić, Slađana
AU  - Galland, Paul
PY  - 2021
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1399
AB  - The growing zone (GZ) of the unicellular coenocytic sporangiophore of Phycomyces blakesleeanus represents the site of stimulus reception (light, gravity, gas) and stimulus response, i.e., local modulations of the elongation growth, which may result, in dependence of the stimulus direction, in tropic bending. Until now, evidence for a possible participation of the columella in sensory reception is absent. We confirm with light microscopy earlier studies that show that the GZ and the columella are not separated by a membrane or cell wall, but rather form a spatial continuum that allows free exchange of cytoplasm and organelle transport. Evidence is presented that the columella is responsive to external stimuli. Columellae, from which spores and sporangial cell wall had been removed, respond to exogenous auxin with a local depolarization of the membrane potential and an increased growth rate of the GZ. In contrast, auxin applied to the GZ causes a decrease of the growth rate irrespective of the presence or absence of sporangia. The response pattern is specific and relevant for the sensory reception of Phycomyces, because the light-insensitive mutant C148carAmadC, which lacks the RAS-GAP protein MADC, displays abnormal IAA sensitivity and membrane depolarization. We argue that the traditional concept of the GZ as the only stimulus-sensitive zone should be abandoned in favor of a model in which GZ and columella operate as a single entity capable to orchestrate a multitude of stimulus inputs, including auxin, to modulate the membrane potential and elongation growth of the GZ.
PB  - Springer Wien, Wien
T2  - Protoplasma
T1  - Signal transduction in Phycomyces sporangiophores: columella as a novel sensory organelle mediating auxin-modulated growth rate and membrane potential
DO  - 10.1007/s00709-021-01709-y
ER  - 

@article{
author = "Živanović, Branka  D. and Danilović Luković, Jelena and Korac, Aleksandra and Stanić, Marina and Spasić, Slađana and Galland, Paul",
year = "2021",
abstract = "The growing zone (GZ) of the unicellular coenocytic sporangiophore of Phycomyces blakesleeanus represents the site of stimulus reception (light, gravity, gas) and stimulus response, i.e., local modulations of the elongation growth, which may result, in dependence of the stimulus direction, in tropic bending. Until now, evidence for a possible participation of the columella in sensory reception is absent. We confirm with light microscopy earlier studies that show that the GZ and the columella are not separated by a membrane or cell wall, but rather form a spatial continuum that allows free exchange of cytoplasm and organelle transport. Evidence is presented that the columella is responsive to external stimuli. Columellae, from which spores and sporangial cell wall had been removed, respond to exogenous auxin with a local depolarization of the membrane potential and an increased growth rate of the GZ. In contrast, auxin applied to the GZ causes a decrease of the growth rate irrespective of the presence or absence of sporangia. The response pattern is specific and relevant for the sensory reception of Phycomyces, because the light-insensitive mutant C148carAmadC, which lacks the RAS-GAP protein MADC, displays abnormal IAA sensitivity and membrane depolarization. We argue that the traditional concept of the GZ as the only stimulus-sensitive zone should be abandoned in favor of a model in which GZ and columella operate as a single entity capable to orchestrate a multitude of stimulus inputs, including auxin, to modulate the membrane potential and elongation growth of the GZ.",
publisher = "Springer Wien, Wien",
journal = "Protoplasma",
title = "Signal transduction in Phycomyces sporangiophores: columella as a novel sensory organelle mediating auxin-modulated growth rate and membrane potential",
doi = "10.1007/s00709-021-01709-y"
}

Živanović, Branka  D., Danilović Luković, J., Korac, A., Stanić, M., Spasić, S.,& Galland, P.. (2021). Signal transduction in Phycomyces sporangiophores: columella as a novel sensory organelle mediating auxin-modulated growth rate and membrane potential. in Protoplasma
Springer Wien, Wien..
https://doi.org/10.1007/s00709-021-01709-y

Živanović, Branka  D., Danilović Luković J, Korac A, Stanić M, Spasić S, Galland P. Signal transduction in Phycomyces sporangiophores: columella as a novel sensory organelle mediating auxin-modulated growth rate and membrane potential. in Protoplasma. 2021;.
doi:10.1007/s00709-021-01709-y .

Živanović, Branka  D., Danilović Luković, Jelena, Korac, Aleksandra, Stanić, Marina, Spasić, Slađana, Galland, Paul, "Signal transduction in Phycomyces sporangiophores: columella as a novel sensory organelle mediating auxin-modulated growth rate and membrane potential" in Protoplasma (2021),
https://doi.org/10.1007/s00709-021-01709-y . .

TY  - 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 . .

TY  - JOUR
AU  - Živanović, Branka  D.
AU  - Ullrich, Kristian K.
AU  - Steffens, Bianka
AU  - Spasić, Slađana
AU  - Galland, Paul
PY  - 2018
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1164
AB  - The roles of fungal auxins in the regulation of elongation growth, photo-, and gravitropism are completely unknown. We analyzed the effects of exogenous IAA (indole-3-acetic acid), various synthetic auxins including 1-NAA (1-naphthaleneacctic acid) and 2,4-D (2,4-dichlorophenoxyacetic acid), and the auxin transport inhibitor NPA (N-1-naphtylphtalamic acid) on the growth rate and bending of the unicellular sporangiophore of the zygomycete fungus. Phycomyces blakesleeanus. Sporangiophores that were submerged in an aqueous buffer responded to IAA with a sustained enhancement of the growth rate, while 1-NAA, 2,4-D. and NPA elicited an inhibition. In contrast, sporangiophores kept in air responded to IAA with a 20 to 40% decrease of the growth rate, while 1-NAA and NPA elicited an enhancement. The unilateral and local application of IAA in the growing zone of the sporangiophore elicited in 30 min a moderate negative tropic bending in wild type C2 and mutant C148madC, which was, however, partially masked by a concomitant avoidance response caused by the aqueous buffer. Auxin transport-related genes ubiquitous in plants were found in a BLAST search of the Phycomyces genome. They included members of the AUX1 (auxin influx carrier protein 1), PILS (PIN-LIKES, auxin transport facilitator protein), and ABCB (plant ATP-binding cassette transporter B) families while members of the PIN family were absent. Our observations imply that IAA represents an intrinsic element of the sensory transduction of Phycomyces and that its mode of action must very likely differ in several respects from that operating in plant.
PB  - Springer Wien, Wien
T2  - Protoplasma
T1  - The effect of auxin (indole-3-acetic acid) on the growth rate and tropism of the sporangiophore of Phycomyces blakesleeanus and identification of auxin-related genes
EP  - 1347
IS  - 5
SP  - 1331
VL  - 255
DO  - 10.1007/s00709-018-1232-2
ER  - 

@article{
author = "Živanović, Branka  D. and Ullrich, Kristian K. and Steffens, Bianka and Spasić, Slađana and Galland, Paul",
year = "2018",
abstract = "The roles of fungal auxins in the regulation of elongation growth, photo-, and gravitropism are completely unknown. We analyzed the effects of exogenous IAA (indole-3-acetic acid), various synthetic auxins including 1-NAA (1-naphthaleneacctic acid) and 2,4-D (2,4-dichlorophenoxyacetic acid), and the auxin transport inhibitor NPA (N-1-naphtylphtalamic acid) on the growth rate and bending of the unicellular sporangiophore of the zygomycete fungus. Phycomyces blakesleeanus. Sporangiophores that were submerged in an aqueous buffer responded to IAA with a sustained enhancement of the growth rate, while 1-NAA, 2,4-D. and NPA elicited an inhibition. In contrast, sporangiophores kept in air responded to IAA with a 20 to 40% decrease of the growth rate, while 1-NAA and NPA elicited an enhancement. The unilateral and local application of IAA in the growing zone of the sporangiophore elicited in 30 min a moderate negative tropic bending in wild type C2 and mutant C148madC, which was, however, partially masked by a concomitant avoidance response caused by the aqueous buffer. Auxin transport-related genes ubiquitous in plants were found in a BLAST search of the Phycomyces genome. They included members of the AUX1 (auxin influx carrier protein 1), PILS (PIN-LIKES, auxin transport facilitator protein), and ABCB (plant ATP-binding cassette transporter B) families while members of the PIN family were absent. Our observations imply that IAA represents an intrinsic element of the sensory transduction of Phycomyces and that its mode of action must very likely differ in several respects from that operating in plant.",
publisher = "Springer Wien, Wien",
journal = "Protoplasma",
title = "The effect of auxin (indole-3-acetic acid) on the growth rate and tropism of the sporangiophore of Phycomyces blakesleeanus and identification of auxin-related genes",
pages = "1347-1331",
number = "5",
volume = "255",
doi = "10.1007/s00709-018-1232-2"
}

Živanović, Branka  D., Ullrich, K. K., Steffens, B., Spasić, S.,& Galland, P.. (2018). The effect of auxin (indole-3-acetic acid) on the growth rate and tropism of the sporangiophore of Phycomyces blakesleeanus and identification of auxin-related genes. in Protoplasma
Springer Wien, Wien., 255(5), 1331-1347.
https://doi.org/10.1007/s00709-018-1232-2

Živanović, Branka  D., Ullrich KK, Steffens B, Spasić S, Galland P. The effect of auxin (indole-3-acetic acid) on the growth rate and tropism of the sporangiophore of Phycomyces blakesleeanus and identification of auxin-related genes. in Protoplasma. 2018;255(5):1331-1347.
doi:10.1007/s00709-018-1232-2 .

Živanović, Branka  D., Ullrich, Kristian K., Steffens, Bianka, Spasić, Slađana, Galland, Paul, "The effect of auxin (indole-3-acetic acid) on the growth rate and tropism of the sporangiophore of Phycomyces blakesleeanus and identification of auxin-related genes" in Protoplasma, 255, no. 5 (2018):1331-1347,
https://doi.org/10.1007/s00709-018-1232-2 . .