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Modelling and experimental analysis of hormonal crosstalk in Arabidopsis.

Liu J, Mehdi S, Topping J, Tarkowski P, Lindsey K - Mol. Syst. Biol. (2010)

Bottom Line: Modelling correctly predicts experimental results for the effect of the pls gene mutation on endogenous cytokinin concentration.Modelling further reveals that a bell-shaped dose-response relationship between endogenous auxin and root length is established via PLS.This combined modelling and experimental analysis provides new insights into the integration of hormonal signals in plants.

View Article: PubMed Central - PubMed

Affiliation: The Integrative Cell Biology Laboratory and The Biophysical Sciences Institute, School of Biological and Biomedical Sciences, Durham University, Durham, UK. junli.liu@durham.ac.uk

ABSTRACT
An important question in plant biology is how genes influence the crosstalk between hormones to regulate growth. In this study, we model POLARIS (PLS) gene function and crosstalk between auxin, ethylene and cytokinin in Arabidopsis. Experimental evidence suggests that PLS acts on or close to the ethylene receptor ETR1, and a mathematical model describing possible PLS-ethylene pathway interactions is developed, and used to make quantitative predictions about PLS-hormone interactions. Modelling correctly predicts experimental results for the effect of the pls gene mutation on endogenous cytokinin concentration. Modelling also reveals a role for PLS in auxin biosynthesis in addition to a role in auxin transport. The model reproduces available mutants, and with new experimental data provides new insights into how PLS regulates auxin concentration, by controlling the relative contribution of auxin transport and biosynthesis and by integrating auxin, ethylene and cytokinin signalling. Modelling further reveals that a bell-shaped dose-response relationship between endogenous auxin and root length is established via PLS. This combined modelling and experimental analysis provides new insights into the integration of hormonal signals in plants.

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Increase in ACC increases both endogenous ethylene and the concentration of the activated form of auxin receptor, Ra*. Ethylene and Ra* contribute antagonistically to PLS expression, with the overall effect of increase in exogenous ACC is predicted to be the decrease in PLS expression.
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f7: Increase in ACC increases both endogenous ethylene and the concentration of the activated form of auxin receptor, Ra*. Ethylene and Ra* contribute antagonistically to PLS expression, with the overall effect of increase in exogenous ACC is predicted to be the decrease in PLS expression.

Mentions: The transcription of the PLS gene itself is regulated by both auxin and ethylene. Model analysis reveals that increase in exogenous auxin, which increases endogenous auxin concentration, increases PLS transcription (data not shown). This reflects the recognition that increase in auxin concentration increases the response of auxin signalling, and subsequently increases PLS expression (Casson et al, 2002). When ACC is exogenously applied, it also increases auxin concentration in wild type (Figure 5B), but it decreases PLS transcription (Figure 7). Model analysis shows that increase in ACC concentration increases both endogenous ethylene and the concentration of the activated form of auxin receptor, Ra*. Ethylene and Ra* contribute antagonistically to PLS expression, with the overall effect of increase in exogenous ACC is predicted to be the decrease of PLS expression (Figure 7). These trends qualitatively agree well with experimental observations (Casson et al, 2002; Chilley et al, 2006).


Modelling and experimental analysis of hormonal crosstalk in Arabidopsis.

Liu J, Mehdi S, Topping J, Tarkowski P, Lindsey K - Mol. Syst. Biol. (2010)

Increase in ACC increases both endogenous ethylene and the concentration of the activated form of auxin receptor, Ra*. Ethylene and Ra* contribute antagonistically to PLS expression, with the overall effect of increase in exogenous ACC is predicted to be the decrease in PLS expression.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2913391&req=5

f7: Increase in ACC increases both endogenous ethylene and the concentration of the activated form of auxin receptor, Ra*. Ethylene and Ra* contribute antagonistically to PLS expression, with the overall effect of increase in exogenous ACC is predicted to be the decrease in PLS expression.
Mentions: The transcription of the PLS gene itself is regulated by both auxin and ethylene. Model analysis reveals that increase in exogenous auxin, which increases endogenous auxin concentration, increases PLS transcription (data not shown). This reflects the recognition that increase in auxin concentration increases the response of auxin signalling, and subsequently increases PLS expression (Casson et al, 2002). When ACC is exogenously applied, it also increases auxin concentration in wild type (Figure 5B), but it decreases PLS transcription (Figure 7). Model analysis shows that increase in ACC concentration increases both endogenous ethylene and the concentration of the activated form of auxin receptor, Ra*. Ethylene and Ra* contribute antagonistically to PLS expression, with the overall effect of increase in exogenous ACC is predicted to be the decrease of PLS expression (Figure 7). These trends qualitatively agree well with experimental observations (Casson et al, 2002; Chilley et al, 2006).

Bottom Line: Modelling correctly predicts experimental results for the effect of the pls gene mutation on endogenous cytokinin concentration.Modelling further reveals that a bell-shaped dose-response relationship between endogenous auxin and root length is established via PLS.This combined modelling and experimental analysis provides new insights into the integration of hormonal signals in plants.

View Article: PubMed Central - PubMed

Affiliation: The Integrative Cell Biology Laboratory and The Biophysical Sciences Institute, School of Biological and Biomedical Sciences, Durham University, Durham, UK. junli.liu@durham.ac.uk

ABSTRACT
An important question in plant biology is how genes influence the crosstalk between hormones to regulate growth. In this study, we model POLARIS (PLS) gene function and crosstalk between auxin, ethylene and cytokinin in Arabidopsis. Experimental evidence suggests that PLS acts on or close to the ethylene receptor ETR1, and a mathematical model describing possible PLS-ethylene pathway interactions is developed, and used to make quantitative predictions about PLS-hormone interactions. Modelling correctly predicts experimental results for the effect of the pls gene mutation on endogenous cytokinin concentration. Modelling also reveals a role for PLS in auxin biosynthesis in addition to a role in auxin transport. The model reproduces available mutants, and with new experimental data provides new insights into how PLS regulates auxin concentration, by controlling the relative contribution of auxin transport and biosynthesis and by integrating auxin, ethylene and cytokinin signalling. Modelling further reveals that a bell-shaped dose-response relationship between endogenous auxin and root length is established via PLS. This combined modelling and experimental analysis provides new insights into the integration of hormonal signals in plants.

Show MeSH
Related in: MedlinePlus