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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.

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Comparison of root hair elongation of auxin response mutants grown in different concentration of glucose containing medium.Effect of glucose on root hair induction of 5 d old light-grown Col and different auxin receptor and signaling mutant seedlings. The Col and mutant seedlings were grown in 1/2MS medium containing 0.8% agar and 1% sucrose for 5 d to promote homogenous growth and then transferred to 1/2MS medium containing 0.8% agar with different concentrations of glucose for 3 d and photographs taken using a Nikon Coolpix camera attached to Nikon Stereo Zoom microscope.
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pone-0004502-g009: Comparison of root hair elongation of auxin response mutants grown in different concentration of glucose containing medium.Effect of glucose on root hair induction of 5 d old light-grown Col and different auxin receptor and signaling mutant seedlings. The Col and mutant seedlings were grown in 1/2MS medium containing 0.8% agar and 1% sucrose for 5 d to promote homogenous growth and then transferred to 1/2MS medium containing 0.8% agar with different concentrations of glucose for 3 d and photographs taken using a Nikon Coolpix camera attached to Nikon Stereo Zoom microscope.

Mentions: To find out if glucose signaling is mediated by auxin response in controlling different root growth parameters and responses, we checked the effect of increasing concentrations of glucose on different auxin perception tir1 and signaling slr1/iaa14, axr3/iaa17 and axr2/iaa7 mutants. Both root length change as well as lateral roots induction was significantly compromised in these mutants on increasing concentrations of glucose. The roots of auxin response mutant tir1, axr2 as well as slr1 are agravitropic in nature when grown in 1% glucose containing medium suggesting a role of proper auxin signaling required for optimal gravitropic response. On increasing concentration of glucose up to 5%, the roots growth of auxin signaling mutants becomes completely randomized with roots starting to go against gravity vector in slr1/iaa14 and axr2/iaa7 mutants (Figure 8; Figure S9) suggesting increasing concentration of glucose can accentuate the growth defect caused by perturbed auxin response/transport. These results suggest that glucose affects different root growth parameters via affecting auxin signaling/transport components. Glucose although could cause root hair initiation in auxin signaling mutant at high concentrations but root hair elongation was severely compromised (Figure 9) suggesting the requirement of normal auxin physiology a prerequisite even for this glucose induced parameter of root growth and development.


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)

Comparison of root hair elongation of auxin response mutants grown in different concentration of glucose containing medium.Effect of glucose on root hair induction of 5 d old light-grown Col and different auxin receptor and signaling mutant seedlings. The Col and mutant seedlings were grown in 1/2MS medium containing 0.8% agar and 1% sucrose for 5 d to promote homogenous growth and then transferred to 1/2MS medium containing 0.8% agar with different concentrations of glucose for 3 d and photographs taken using a Nikon Coolpix camera attached to Nikon Stereo Zoom microscope.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0004502-g009: Comparison of root hair elongation of auxin response mutants grown in different concentration of glucose containing medium.Effect of glucose on root hair induction of 5 d old light-grown Col and different auxin receptor and signaling mutant seedlings. The Col and mutant seedlings were grown in 1/2MS medium containing 0.8% agar and 1% sucrose for 5 d to promote homogenous growth and then transferred to 1/2MS medium containing 0.8% agar with different concentrations of glucose for 3 d and photographs taken using a Nikon Coolpix camera attached to Nikon Stereo Zoom microscope.
Mentions: To find out if glucose signaling is mediated by auxin response in controlling different root growth parameters and responses, we checked the effect of increasing concentrations of glucose on different auxin perception tir1 and signaling slr1/iaa14, axr3/iaa17 and axr2/iaa7 mutants. Both root length change as well as lateral roots induction was significantly compromised in these mutants on increasing concentrations of glucose. The roots of auxin response mutant tir1, axr2 as well as slr1 are agravitropic in nature when grown in 1% glucose containing medium suggesting a role of proper auxin signaling required for optimal gravitropic response. On increasing concentration of glucose up to 5%, the roots growth of auxin signaling mutants becomes completely randomized with roots starting to go against gravity vector in slr1/iaa14 and axr2/iaa7 mutants (Figure 8; Figure S9) suggesting increasing concentration of glucose can accentuate the growth defect caused by perturbed auxin response/transport. These results suggest that glucose affects different root growth parameters via affecting auxin signaling/transport components. Glucose although could cause root hair initiation in auxin signaling mutant at high concentrations but root hair elongation was severely compromised (Figure 9) suggesting the requirement of normal auxin physiology a prerequisite even for this glucose induced parameter of root growth and development.

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