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ABSTRACT: Plants have the ability to adjust its physiology and metabolism to the changes of nutrient availability in the environment. Since a number of common responses are regulated by sugar and auxin, the obvious question arises is whether sugar and auxin act interdependently to bring about changes in plant morphology. In the February issue of the PLoS ONE, we presented detailed investigation of glucose and auxin signaling interaction in controlling root growth and development in Arabidopsis thaliana seedlings. Further analysis of tissue specific regulation of glucose auxin signaling interaction may provide some insight as to how these two signaling molecules interact to control the morphogenic changes during seedling development.
Plant signaling & behavior 09/2009; 4(9):862-3.
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ABSTRACT: P lants have the ability to adjust its physiology and metabolism to the changes of nutrient availability in the environment. Since a number of com-mon responses are regulated by sugar and auxin, the obvious question arises is whether sugar and auxin act interdepen-dently to bring about changes in plant morphology. In the February issue of the PLoS ONE, 1 we presented detailed inves-tigation of glucose and auxin signaling interaction in controlling root growth and development in Arabidopsis thaliana seedlings. Further analysis of tissue spe-cific regulation of glucose auxin signal-ing interaction may provide some insight as to how these two signaling molecules interact to control the morphogenic changes during seedling development. In literature there are several reports about sugar and phytohormones interaction. The possible link of sugar with auxin was sug-gested by some sugar related mutants that were also perturbed in auxin responses. The glucose sensor HXK mutant gin2 also display resistance towards exogenous auxin. 2 The turanose insensitive, tin mutant encodes for a WOX5 gene that is induced by both turanose and auxin. WOX gene plays an important role in maintaining auxin maxima at root tip and root formation and patterning by acting as a negative trigger of IAA homeostasis. 3 A new allele of hls1 (hookless1) mutant is shown to be resistant to both sugar and auxin responses. 4 Along with these reports, a number of common responses are reported to be controlled both by sugar and auxin defining the need to fur-ther study the mechanism of interaction between these molecules. In our study, we have observed that the increasing concentration of glucose can also bring more randomization in root growth direction along with changes in other parameters such as root length, lateral root production and root hair for-mation. These responses are dependent on HXK mediated signaling to different extents as suggested by the response of gin2 (glucose receptor hexokinase) mutant towards exogenous sugars. In order to find out the extent of inter-action between auxin and glucose, whole genome transcript profiling was done. Microarray analysis suggested that total 604 genes were two or more fold up/ downregulated by IAA. Glucose alone could regulate 377 (62%) of these 604 IAA regulated genes suggesting a large overlap between the two signaling mol-ecules and could be a possible explanation for controlling a large number of common responses shared by glucose and auxin. Out of these 377 genes 68% were regu-lated agonistically and 32% were regulated antagonistically by glucose. Glucose could also modulate the extent of regulation of almost 63% genes induced or repressed by IAA. Most of the IAA regulated genes, which were agonistically affected by glucose, were regulated transcriptionally by glu-cose alone, whereas most of the IAA regu-lated genes in which glucose antagonizes IAA mediated up or downregulation were not regulated transcriptionally by glucose alone. This suggests that antagonistic action of glucose on IAA regulated genes either requires auxin regulated factor/s or may control gene expression through some non transcriptional pathways in presence of auxin. The GUS expression of
Plant Signaling and Behaviour. 09/2009; 4(September):862–863.
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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.
PLoS ONE 02/2009; 4. · 4.09 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: 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.
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.
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.
PLoS ONE 02/2009; 4(2):e4502. · 4.09 Impact Factor
