BHLH32 modulates several biochemical and morphological processes that respond to Pi starvation in Arabidopsis

Chen, Z.-H., Nimmo, G.A., Jenkins, G.I. and Nimmo, H.G. (2007) BHLH32 modulates several biochemical and morphological processes that respond to Pi starvation in Arabidopsis. Biochemical Journal, 405(1), pp. 191-198.

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Abstract

P<sub>i</sub> (inorganic phosphate) limitation severely impairs plant growth and reduces crop yield. Hence plants have evolved several biochemical and morphological responses to Pi starvation that both enhance uptake and conserve use. The mechanisms involved in P<sub>i</sub> sensing and signal transduction are not completely understood. In the present study we report that a previously uncharacterized transcription factor, BHLH32, acts as a negative regulator of a range of Pi starvation-induced processes in Arabidopsis. In bhlh32 mutant plants in P<sub>i</sub>-sufficient conditions, expression of several Pi starvation-induced genes, formation of anthocyanins, total P<sub>i</sub> content and root hair formation were all significantly increased compared with the wild-type. Among the genes negatively regulated by BHLH32 are those encoding PPCK (phosphoenolpyruvate carboxylase kinase), which is involved in modifying metabolism so that P<sub>i</sub> is spared. The present study has shown that PPCK genes are rapidly induced by P<sub>i</sub> starvation leading to increased phosphorylation of phosphoenolpyruvate carboxylase. Furthermore, several Arabidopsis proteins that regulate epidermal cell differentiation [TTG1 (TRANSPARENT TESTA GLABRA1), GL3 (GLABRA3) and EGL3 (ENHANCER OF GL3)] positively regulate PPCK gene expression in response to P<sub>i</sub> starvation. BHLH32 can physically interact with TTG1 and GL3. We propose that BHLH32 interferes with the function of TTG1-containing complexes and thereby affects several biochemical and morphological processes that respond to P<sub>i</sub> availability.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Nimmo, Dr Gillian and Nimmo, Professor Hugh and Jenkins, Professor Gareth
Authors: Chen, Z.-H., Nimmo, G.A., Jenkins, G.I., and Nimmo, H.G.
Subjects:Q Science > QH Natural history > QH301 Biology
Q Science > QP Physiology
College/School:College of Medical Veterinary and Life Sciences
College of Medical Veterinary and Life Sciences > Institute of Molecular Cell and Systems Biology
College of Medical Veterinary and Life Sciences > School of Life Sciences
Journal Name:Biochemical Journal
Publisher:Portland Press Ltd.
ISSN:0264-6021
ISSN (Online):1470-8728

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