Carbon source–sink relationship in Arabidopsis thaliana: the role of sucrose transporters

Abstract

Main conclusion The regulation of source-to-sink sucrose transport is associated with AtSUC and AtSWEET sucrose transporters’ gene expression changes in plants grown hydroponically under different physiological conditions. Source-to-sink transport of sucrose is one of the major determinants of plant growth. Whole-plant carbohydrates’ partitioning requires the specific activity of membrane sugar transporters. In Arabidopsis thaliana plants, two families of transporters are involved in sucrose transport: AtSUCs and AtSWEETs. This study is focused on the comparison of sucrose transporter gene expression, soluble sugar and starch levels and long distance sucrose transport, in leaves and sink organs (mainly roots) in different physiological conditions (along the plant life cycle, during a diel cycle, and during an osmotic stress) in plants grown hydroponically. In leaves, the AtSUC2, AtSWEET11, and 12 genes known to be involved in phloem loading were highly expressed when sucrose export was high and reduced during osmotic stress. In roots, AtSUC1 was highly expressed and its expression profile in the different conditions tested suggests that it may play a role in sucrose unloading in roots and in root growth. The SWEET transporter genes AtSWEET12, 13, and 15 were found expressed in all organs at all stages studied, while differential expression was noticed for AtSWEET14 in roots, stems, and siliques and AtSWEET9, 10 expressions were only detected in stems and siliques. A role for these transporters in carbohydrate partitioning in different source–sink status is proposed, with a specific attention on carbon demand in roots. During development, despite trophic competition with others sinks, roots remained a significant sink, but during osmotic stress, the amount of translocated [U-14C]-sucrose decreased for rosettes and roots. Altogether, these results suggest that source–sink relationship may be linked with the regulation of sucrose transporter gene expression.Electronic supplementary materialThe online version of this article (10.1007/s00425-017-2807-4) contains supplementary material, which is available to authorized users.

Natural variation and selection in GmSWEET39 affect soybean seed oil content

“…5d,e) and the GmSWEET39 CDS2 overexpressing lines had higher soluble sugar content than control in the siliques of Arabidopsis (Fig. In most plants, carbon dioxide is assimilated in mesophyll cells (source) by photosynthesis to produce starch or sucrose, with sucrose as the primary transported form and SWEETs are responsible for sucrose efflux (Doidy et al, 2012;Durand et al, 2018). In most plants, carbon dioxide is assimilated in mesophyll cells (source) by photosynthesis to produce starch or sucrose, with sucrose as the primary transported form and SWEETs are responsible for sucrose efflux (Doidy et al, 2012;Durand et al, 2018).…”

Sugars en route to the roots. Transport, metabolism and storage within plant roots and towards microorganisms of the rhizosphere

“…Starch is an important form of C storage that plays an significant role in regulating the carbon status of the plant during the day/night cycle and in response to environmental cues (Durand et al ). In addition, a fine regulation of C allocation between source and sink organs (roots, flowers, fruits and seeds) occurs throughout plant development (Durand et al ). A specific sugar storage process is implicated in a number of plant species that develop storage organs (Fig.…”

“…Root exudation cannot be accurately measured as it is difficult to discriminate between root and microbial exudates, even in axenic cultures. In Arabidopsis hydroponic cultures, we traced source‐to‐sink C partitioning at different stages of development by measuring the [U‐ 14 C] sucrose transport (Durand et al ). Our results showed high C exudation (around 20%) at the vegetative stage, then exudation decreased at the reproductive stage.…”

“…Besides, roots must be supplied with sucrose for metabolic maintenance, even when root growth has ceased. Roots are therefore a typical sink organ, especially at early developmental stages and will be competing with other sinks during later stages (Durand et al ).…”

Trehalose 6-Phosphate Regulates Photosynthesis and Assimilate Partitioning in Reproductive Tissue

“…In explaining elevated cadmium and salt, through antioxidant mechanisms (Brychkova et al, 2008), and 345 jasmonic acid and ABA signalling (Takagi et al, 2016). Arabidopsis (Durand et al, 2017). Sucrose levels in leaves of transgenics were also An association between T6P and sucrose is well established (Lunn et al,391 2006; Nunes et al, 2013a).…”