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


RESULTS
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.


CONCLUSIONS
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.
Mishra
Bhuwaneshwar S
BS
National Institute for Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India.
Singh
Manjul
M
Aggrawal
Priyanka
P
Laxmi
Ashverya
A
D017360:Arabidopsis / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D005947:Glucose / Q000378:metabolism* / Q000502:physiology; D007210:Indoleacetic Acids / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism / Q000502:physiology; D018517:Plant Roots / Q000254:growth & development; D012639:Seeds / Q000254:growth & development; D015398:Signal Transduction
D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D005947:Glucose