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Glucose and auxin signaling interaction in controlling Arabidopsis thaliana seedlings root growth and development.

Mishra BS, Singh M, Aggrawal P, Laxmi A - PLoS ONE (2009)

Bottom Line: Interestingly, glucose could affect induction or repression of IAA affected genes (35%) even if glucose alone had no significant effect on the transcription of these genes itself.Arabidopsis auxin receptor tir1 and response mutants, axr2, axr3 and slr1 not only display a defect in glucose induced change in root length, root hair elongation and lateral root production but also accentuate glucose induced increase in root growth randomization from vertical suggesting glucose effects on plant root growth and development are mediated by auxin signaling components.Our findings implicate an important role of the glucose interacting with auxin signaling and transport machinery to control seedling root growth and development in changing nutrient conditions.

View Article: PubMed Central - PubMed

Affiliation: National Institute for Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India.

ABSTRACT

Background: Plant root growth and development is highly plastic and can adapt to many environmental conditions. Sugar signaling has been shown to affect root growth and development by interacting with phytohormones such as gibberellins, cytokinin and abscisic acid. Auxin signaling and transport has been earlier shown to be controlling plant root length, number of lateral roots, root hair and root growth direction.

Principal findings: Increasing concentration of glucose not only controls root length, root hair and number of lateral roots but can also modulate root growth direction. Since root growth and development is also controlled by auxin, whole genome transcript profiling was done to find out the extent of interaction between glucose and auxin response pathways. Glucose alone could transcriptionally regulate 376 (62%) genes out of 604 genes affected by IAA. Presence of glucose could also modulate the extent of regulation 2 fold or more of almost 63% genes induced or repressed by IAA. Interestingly, glucose could affect induction or repression of IAA affected genes (35%) even if glucose alone had no significant effect on the transcription of these genes itself. Glucose could affect auxin biosynthetic YUCCA genes family members, auxin transporter PIN proteins, receptor TIR1 and members of a number of gene families including AUX/IAA, GH3 and SAUR involved in auxin signaling. Arabidopsis auxin receptor tir1 and response mutants, axr2, axr3 and slr1 not only display a defect in glucose induced change in root length, root hair elongation and lateral root production but also accentuate glucose induced increase in root growth randomization from vertical suggesting glucose effects on plant root growth and development are mediated by auxin signaling components.

Conclusion: Our findings implicate an important role of the glucose interacting with auxin signaling and transport machinery to control seedling root growth and development in changing nutrient conditions.

Show MeSH
Accumulation and spatial expression of auxin transporter PIN2 as analyzed by PIN2::GFP expression in root tip by confocal microscope and root basipetal transport as measured using radio-labeled IAA.(A) PIN2::GFP expression in 5 d old light-grown seedlings Arabidopsis root tip treated for 4–5 h with different concentrations of glucose containing liquid MS medium. Increasing concentrations of glucose promotes more PIN2::GFP accumulation in the plasma membrane. Scale bar 50 µm for upper panel and 10 µm for lower panel. (B) Basipetal auxin transport increases on increasing glucose concentrations in 5 d old light-grown Arabidopsis seedling root tip as measured by H3(IAA) accumulation.
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pone-0004502-g007: Accumulation and spatial expression of auxin transporter PIN2 as analyzed by PIN2::GFP expression in root tip by confocal microscope and root basipetal transport as measured using radio-labeled IAA.(A) PIN2::GFP expression in 5 d old light-grown seedlings Arabidopsis root tip treated for 4–5 h with different concentrations of glucose containing liquid MS medium. Increasing concentrations of glucose promotes more PIN2::GFP accumulation in the plasma membrane. Scale bar 50 µm for upper panel and 10 µm for lower panel. (B) Basipetal auxin transport increases on increasing glucose concentrations in 5 d old light-grown Arabidopsis seedling root tip as measured by H3(IAA) accumulation.

Mentions: Since PIN proteins show a definite spatial-temporal expression and there partitioning in the cell is very important for determining the flow of auxin transport and thus the gravitropism, we also checked the expression of PIN2::GFP [10] proteins. On increasing concentration of glucose, the level of PIN2::GFP was also found to increase on both short term as well as long term treatment. In accordance, basipetal auxin transport was found to be more in seedlings treated with glucose suggesting that glucose signaling in fact does increase the auxin polar transport (Figure 7). A number of cells did show more accumulation of PIN2::GFP on the lateral walls on higher concentrations of glucose as compared to seedlings shifted to 0% glucose containing media.


Glucose and auxin signaling interaction in controlling Arabidopsis thaliana seedlings root growth and development.

Mishra BS, Singh M, Aggrawal P, Laxmi A - PLoS ONE (2009)

Accumulation and spatial expression of auxin transporter PIN2 as analyzed by PIN2::GFP expression in root tip by confocal microscope and root basipetal transport as measured using radio-labeled IAA.(A) PIN2::GFP expression in 5 d old light-grown seedlings Arabidopsis root tip treated for 4–5 h with different concentrations of glucose containing liquid MS medium. Increasing concentrations of glucose promotes more PIN2::GFP accumulation in the plasma membrane. Scale bar 50 µm for upper panel and 10 µm for lower panel. (B) Basipetal auxin transport increases on increasing glucose concentrations in 5 d old light-grown Arabidopsis seedling root tip as measured by H3(IAA) accumulation.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2637607&req=5

pone-0004502-g007: Accumulation and spatial expression of auxin transporter PIN2 as analyzed by PIN2::GFP expression in root tip by confocal microscope and root basipetal transport as measured using radio-labeled IAA.(A) PIN2::GFP expression in 5 d old light-grown seedlings Arabidopsis root tip treated for 4–5 h with different concentrations of glucose containing liquid MS medium. Increasing concentrations of glucose promotes more PIN2::GFP accumulation in the plasma membrane. Scale bar 50 µm for upper panel and 10 µm for lower panel. (B) Basipetal auxin transport increases on increasing glucose concentrations in 5 d old light-grown Arabidopsis seedling root tip as measured by H3(IAA) accumulation.
Mentions: Since PIN proteins show a definite spatial-temporal expression and there partitioning in the cell is very important for determining the flow of auxin transport and thus the gravitropism, we also checked the expression of PIN2::GFP [10] proteins. On increasing concentration of glucose, the level of PIN2::GFP was also found to increase on both short term as well as long term treatment. In accordance, basipetal auxin transport was found to be more in seedlings treated with glucose suggesting that glucose signaling in fact does increase the auxin polar transport (Figure 7). A number of cells did show more accumulation of PIN2::GFP on the lateral walls on higher concentrations of glucose as compared to seedlings shifted to 0% glucose containing media.

Bottom Line: Interestingly, glucose could affect induction or repression of IAA affected genes (35%) even if glucose alone had no significant effect on the transcription of these genes itself.Arabidopsis auxin receptor tir1 and response mutants, axr2, axr3 and slr1 not only display a defect in glucose induced change in root length, root hair elongation and lateral root production but also accentuate glucose induced increase in root growth randomization from vertical suggesting glucose effects on plant root growth and development are mediated by auxin signaling components.Our findings implicate an important role of the glucose interacting with auxin signaling and transport machinery to control seedling root growth and development in changing nutrient conditions.

View Article: PubMed Central - PubMed

Affiliation: National Institute for Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India.

ABSTRACT

Background: Plant root growth and development is highly plastic and can adapt to many environmental conditions. Sugar signaling has been shown to affect root growth and development by interacting with phytohormones such as gibberellins, cytokinin and abscisic acid. Auxin signaling and transport has been earlier shown to be controlling plant root length, number of lateral roots, root hair and root growth direction.

Principal findings: Increasing concentration of glucose not only controls root length, root hair and number of lateral roots but can also modulate root growth direction. Since root growth and development is also controlled by auxin, whole genome transcript profiling was done to find out the extent of interaction between glucose and auxin response pathways. Glucose alone could transcriptionally regulate 376 (62%) genes out of 604 genes affected by IAA. Presence of glucose could also modulate the extent of regulation 2 fold or more of almost 63% genes induced or repressed by IAA. Interestingly, glucose could affect induction or repression of IAA affected genes (35%) even if glucose alone had no significant effect on the transcription of these genes itself. Glucose could affect auxin biosynthetic YUCCA genes family members, auxin transporter PIN proteins, receptor TIR1 and members of a number of gene families including AUX/IAA, GH3 and SAUR involved in auxin signaling. Arabidopsis auxin receptor tir1 and response mutants, axr2, axr3 and slr1 not only display a defect in glucose induced change in root length, root hair elongation and lateral root production but also accentuate glucose induced increase in root growth randomization from vertical suggesting glucose effects on plant root growth and development are mediated by auxin signaling components.

Conclusion: Our findings implicate an important role of the glucose interacting with auxin signaling and transport machinery to control seedling root growth and development in changing nutrient conditions.

Show MeSH