Glucose control of root growth direction in Arabidopsis thaliana

Abstract

Directional growth of roots is a complex process that is modulated by various environmental signals. This work shows that presence of glucose (Glc) in the medium also extensively modulated seedling root growth direction. Glc modulation of root growth direction was dramatically enhanced by simultaneous brassinosteroid (BR) application. Glc enhanced BR receptor BRASSINOSTEROID INSENSITIVE1 (BRI1) endocytosis from plasma membrane to early endosomes. Glc-induced root deviation was highly enhanced in a PP2A-defective mutant, roots curl in naphthyl phthalamic acid 1-1 (rcn1-1) suggesting that there is a role of phosphatase in Glc-induced root-growth deviation. RCN1, therefore, acted as a link between Glc and the BR-signalling pathway. Polar auxin transport worked further downstream to BR in controlling Glc-induced root deviation response. Glc also affected other root directional responses such as root waving and coiling leading to altered root architecture. High light intensity mimicked the Glc-induced changes in root architecture that were highly reduced in Glc-signalling mutants. Thus, under natural environmental conditions, changing light flux in the environment may lead to enhanced Glc production/response and is a way to manipulate root architecture for optimized development via integrating several extrinsic and intrinsic signalling cues.

Multiple Interactions between Glucose and Brassinosteroid Signal Transduction Pathways in Arabidopsis Are Uncovered by Whole-Genome Transcriptional Profiling

“…UDP-glycosyltransferases UGT73C5 and UGT73C6 function in conjugation of Glc to BR, which ultimately leads to reduced BR activity (Poppenberger et al, 2005;Husar et al, 2011). Recently, our group has also shown a dual role for BR-Glc cross talk in modulating shoot and root gravitropic responses of Arabidopsis seedlings (Gupta et al, 2012;Singh et al, 2014). Although a number of developmental responses of early seedlings are simultaneously controlled by BR and sugar, no systematic study has been performed to explore the interaction between Glc and BR signaling on global gene expression profiles and, in turn, on plant growth and development in the dark.…”

“…Apart from their metabolic functions, sugars such as Suc and Glc have also been reported to act as signals that can trigger changes in gene expression in plants (Price et al, 2004). Glc as a signaling molecule can also influence almost every aspect of plant growth and development such as cell proliferation and death, cell expansion and elongation, seed germination, seedling growth and development, primary root length, shoot and root gravitropism, lateral roots, root hairs, shoot meristem maintenance, reproduction, senescence, photosynthetic gene expression, crop yield and product quality, carbon and nitrogen metabolism, and stress responses (Rolland et al, 2002(Rolland et al, , 2006Rolland and Sheen, 2005;Chen et al, 2006;Ramon et al, 2008;Mishra et al, 2009;Smeekens et al, 2010;Eveland and Jackson, 2012;Gupta et al, 2012;Singh et al, 2014). There are three distinct Glc-signaling pathways in plants: the Arabidopsis (Arabidopsis thaliana) HEXOKI-NASE1 (AtHXK1) signaling function-dependent pathway, the AtHXK1 catalytic function-dependent pathway, and the AtHXK1-independent pathway (Xiao et al, 2000).…”

Interaction between Glucose and Brassinosteroid during the Regulation of Lateral Root Development in Arabidopsis

“…In plants, roots function as a vital system essential for optimal growth and overall fitness. Root elongation, root branching via lateral root (LR) formation, and root direction determine root system architecture, which allows the plant to adapt to continuously changing environmental conditions as well as intrinsic cues (Malamy, 2005;Cuesta et al, 2013;Singh et al, 2014a). LR formation is an important adaptive feature that provides flexibility to the entire root system toward changes in environmental conditions.…”

“…Glc and auxin can interact extensively to control many aspects of root architecture, such as root elongation, LR production, root hair development, and root directional growth (Mishra et al, 2009;Mudgil et al, 2009;Booker et al, 2010;Yuan et al, 2014). However, there are very few reports in the literature that either directly or indirectly link BR responses to sugar signaling (Laxmi et al, 2004;Rognoni et al, 2007;Gupta et al, 2012;Singh et al, 2014a). In this study, we aim to analyze the nature of the interaction between Glc and BR signaling and find its molecular bases during the regulation of LR emergence using the model plant system Arabidopsis.…”

Mycorrhizal Fungi Regulate Root Responses and Leaf Physiological Activities in Trifoliate Orange

“…A relatively greater hexose level in AMF plants would provide greater substrates for the growth of both AMF and roots. Glucose stimulates the accumulation of a transcription factor or Auxin-mediated signalling for root initiation (Mishra et al, 2009;Singh et al, 2014). As a result, the AMF-induced root modification is so closely related to the AMF-stimulated sucrose cleavage.…”