GO:0015770 sucrose transport: Phloem Loading Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0015770 sucrose transport is defined as the directed movement of sucrose into, out of or within a cell, or between cells by means of some agent such as a transporter or pore.
• Sucrose is the principal transport sugar in most higher plants, moving from source leaves to sink tissues through the phloem.
• SWEET proteins mediate sucrose efflux from phloem parenchyma cells, a key step for phloem loading and long-distance transport.
• SUC2/SUT sucrose transporters load sucrose into the phloem and are regulated by developmental and environmental signals, including the EIN3-SUC2 module.
• Sucrose transport is essential for seed development, starch accumulation in wheat, root growth, and wood formation in trees.
• Dysregulation of sucrose transport can impair sink strength and biomass allocation, making it a target for crop improvement and bioenergy research.
Description
Sucrose transport (GO:0015770) is a fundamental biological process that enables the movement of the disaccharide sucrose across cellular membranes and between cells. In higher plants, sucrose is the primary product of photosynthesis and the main sugar transported from source tissues, such as mature leaves, to sink tissues, including roots, seeds, and developing wood. This process is mediated by specialized transporter proteins that facilitate sucrose efflux, uptake, and intracellular distribution. Understanding sucrose transport is critical for plant physiology, as it directly influences growth, yield, and stress responses. In yeast and other organisms, sucrose transport and dissimilation are also important for metabolic engineering and industrial applications. The study of sucrose transport spans molecular, cellular, and organismal levels, with implications for agriculture, forestry, and biotechnology.
sucrose transport At A Glance
| GO ID | GO:0015770 |
|---|---|
| GO term | sucrose transport |
| Ontology | biological_process |
| Synonym | none |
| Major function | Directed movement of sucrose across membranes via transporters or pores |
| Definition source | QuickGO |
| Related transporters | SWEET proteins, SUC/SUT transporters |
| Key organisms | Plants, yeast, and other organisms |
| Research relevance | Phloem loading, seed filling, wood formation, metabolic engineering |
What Is GO:0015770?
According to the Gene Ontology, GO:0015770 sucrose transport is defined as the directed movement of sucrose into, out of or within a cell, or between cells by means of some agent such as a transporter or pore. Sucrose is the disaccharide fructofuranosyl-glucopyranoside. This process encompasses the translocation of sucrose across biological membranes, typically mediated by specific carrier proteins, and is distinct from sucrose metabolism or signaling.
Why Is sucrose transport Important in Cell Biology?
Sucrose transport is central to carbon allocation in plants, directly affecting crop yield, seed development, and biomass production. It is also a key determinant of sink strength and stress tolerance, as sucrose distribution influences root growth and storage organ filling. In trees, vacuolar sucrose transport is required for wood formation, linking sugar transport to carbon sequestration and bioenergy. In yeast, efficient sucrose transport and dissimilation are critical for industrial fermentation and metabolic engineering. Thus, understanding sucrose transport mechanisms provides insights into fundamental biology and offers targets for crop improvement and biotechnological applications.
• Sucrose transport is essential for phloem loading and long-distance sugar translocation in plants.
• It determines sink strength and crop yield by supplying sugars to developing seeds and fruits.
• SUC2-mediated sucrose transport regulates root growth through the EIN3-SUC2 module.
• Vacuolar sucrose transport is required for wood formation in Populus tomentosa.
• In yeast, sucrose transport and dissimilation efficiency impact industrial fermentation.
• Dysfunctional sucrose transport can lead to impaired growth and reduced biomass.
• Sucrose transporters are targets for improving stress tolerance and nutrient allocation.
• Understanding sucrose transport aids in engineering plants with enhanced carbon partitioning.
• It is a model system for studying membrane transport and energy coupling.
• Sucrose transport research bridges molecular biology, physiology, and agronomy.
What Happens During sucrose transport?
Sucrose efflux from source cells
In simple terms: Sugar made in leaves is pushed out of the cells that produce it.
In source leaves, sucrose synthesized in mesophyll cells moves into the apoplast via efflux transporters. SWEET proteins mediate sucrose efflux from phloem parenchyma cells, a key step for phloem transport. This efflux is essential for establishing a concentration gradient that drives subsequent uptake into the phloem.
Phloem loading
In simple terms: Sugar is actively pumped into the phloem tubes for long-distance travel.
Sucrose is loaded into the phloem sieve element-companion cell complex by SUC/SUT transporters, which are proton-coupled symporters. This active loading creates high sucrose concentrations in the phloem, driving pressure-driven bulk flow to sink tissues. The EIN3-SUC2 module regulates SUC2 expression to promote root growth by modulating sucrose transport.
Long-distance transport
In simple terms: Sugar travels through the plant's vascular highway to reach distant organs.
Once loaded, sucrose is transported through the phloem to sink tissues such as roots, seeds, and developing wood. This long-distance transport is driven by osmotic pressure gradients and is essential for distributing carbon throughout the plant. In Populus tomentosa, vacuolar sucrose transport in ray cells is required for wood formation.
Sucrose uptake into sink cells
In simple terms: Sugar is taken up by the cells that need it for growth or storage.
At sink tissues, sucrose is unloaded from the phloem and taken up by sink cells via sucrose transporters or symplastic pathways. In developing wheat seeds, sucrose transport and metabolism to starch are tightly coordinated to support grain filling. In rice, sucrose transporters play critical roles in grain yield and stress responses.
Intracellular and vacuolar transport
In simple terms: Sugar can also move into storage compartments inside cells.
Sucrose may be transported into vacuoles for storage or osmotic regulation. In Populus tomentosa, a ray-localized vacuolar sucrose transport is required for wood formation. In yeast, sucrose transport across the plasma membrane is coupled to energy metabolism and dissimilation efficiency.
Key Genes Involved in GO:0015770 sucrose transport
The following genes and proteins are central to sucrose transport (GO:0015770) based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| SWEET | Sucrose efflux from phloem parenchyma | Key step for phloem loading and transport |
| SUC2 | Sucrose uptake into phloem | Regulated by EIN3; affects root growth |
| SUT | Sucrose transport in various tissues | Proton-coupled symporters in plants |
| SUS | Sucrose synthase, sucrose cleavage | Links transport to metabolism |
| SPS | Sucrose phosphate synthase | Sucrose synthesis for transport |
| EIN3 | Transcription factor regulating SUC2 | Mediates ethylene signaling to sucrose transport |
| OsSUT1 | Rice sucrose transporter | Grain filling and stress response |
| OsSUT2 | Rice sucrose transporter | Vacuolar sucrose transport |
| TaSUT1 | Wheat sucrose transporter | Seed development and starch accumulation |
| TaSWEET | Wheat SWEET effluxer | Phloem loading in wheat |
| PtoSUT | Populus sucrose transporter | Wood formation |
| PtoSWEET | Populus SWEET effluxer | Ray cell sucrose transport |
| ScSUC2 | Yeast invertase | Sucrose utilization in yeast |
| HXT | Yeast hexose transporters | Glucose uptake after sucrose hydrolysis |
| MST | Monosaccharide transporter family | Related sugar transport |
| STP | Sugar transport protein | Hexose transport in plants |
| ERD6-like | Vacuolar sugar transporter | Intracellular sucrose transport |
How Is sucrose transport Regulated?
Sucrose transport is regulated at multiple levels. In plants, the EIN3 transcription factor directly regulates SUC2 expression to promote root growth in response to ethylene signaling. Sucrose transporter genes are also responsive to developmental cues and environmental factors such as light and stress. In yeast, sucrose transport and dissimilation are regulated by energy status and metabolic demand. Post-translational regulation and protein trafficking of transporters further modulate transport activity.
sucrose transport and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| SUC2 | Impaired root growth | Arabidopsis suc2 knockout |
| SWEET | Defective phloem loading | Arabidopsis sweet mutants |
| TaSUT1 | Reduced seed starch | Wheat RNAi knockdown |
| PtoSUT | Defective wood formation | Populus knockout |
| ScSUC2 | Poor sucrose fermentation | Yeast deletion |
Sucrose transport and plant growth disorders
Impaired sucrose transport leads to reduced sink strength, stunted growth, and yield loss in crops. Mutations in sucrose transporters can cause developmental defects and altered carbon allocation.
Sucrose transport in wood formation and biomass
In Populus tomentosa, disruption of vacuolar sucrose transport in ray cells impairs wood formation, linking sucrose transport to biomass production. This has implications for bioenergy and carbon sequestration.
Sucrose transport in seed development and starch accumulation
In wheat, sucrose transport and metabolism to starch are critical for seed development; defects can reduce grain filling and quality. Similar mechanisms operate in rice and other cereals.
Sucrose transport in yeast metabolic engineering
In yeast, inefficient sucrose transport and dissimilation reduce fermentation yields, impacting industrial biotechnology. Engineering sucrose transporters can improve substrate utilization.
From sucrose transport-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does SUC2 mediate root growth? | SUC2 knockout in Arabidopsis |
| Is SWEET required for phloem loading? | SWEET point mutation in Arabidopsis |
| Does vacuolar sucrose transport affect wood formation? | PtoSUT knock-in in Populus |
| How does EIN3 regulate SUC2? | EIN3 overexpression in Arabidopsis |
| Can sucrose transport be engineered in yeast? | ScSUC2 overexpression in yeast |
| What is the role of TaSUT1 in wheat seeds? | TaSUT1 knockout in wheat |
How to Study the sucrose transport Process
| Method | What It Measures | Typical Application |
|---|---|---|
| RNA-seq | Gene expression levels | Identify sucrose transporter expression patterns |
| Proteomics | Protein abundance and modifications | Characterize transporter proteins |
| Knockout mutants | Loss-of-function phenotypes | Determine gene function in transport |
| Overexpression | Gain-of-function effects | Enhance sucrose transport |
| Transport assays | Sucrose uptake rates | Measure transporter activity |
| Live-cell imaging | Protein localization | Visualize transporter dynamics |
| Yeast complementation | Functional rescue | Test plant transporters in yeast |
Transcriptomics and RNA-seq
RNA-seq can quantify expression of sucrose transporter genes across tissues and conditions, revealing regulatory patterns.
Proteomics and membrane protein analysis
Proteomic approaches identify sucrose transporter proteins and their post-translational modifications, aiding functional characterization.
Genetic and mutant analysis
Knockout and knockdown mutants of sucrose transporters reveal their roles in growth, development, and stress responses.
Transport assays and imaging
Radioactive or fluorescent sucrose uptake assays and live-cell imaging measure transport activity and localization.
How CRISPR Can Be Used to Study GO:0015770 sucrose transport
Knockout
CRISPR knockout of sucrose transporter genes such as SUC2 or SWEET can reveal their essential roles in phloem loading and root growth.
Point Mutation
Introducing point mutations in transporter genes can dissect substrate specificity and regulatory phosphorylation sites.
Knock-in
Knock-in of tagged transporters enables live-cell imaging and interaction studies in native contexts.
Overexpression
Overexpression of sucrose transporters can enhance sink strength and biomass, as shown for SUC2 and SWEET.
How EDITGENE Supports sucrose transport Research
Researchers studying sucrose transport-related genes often need to determine whether a candidate gene is causally involved in sugar allocation, growth, or stress responses. EDITGENE provides comprehensive CRISPR services to generate precise cell and animal models for functional validation.
Contact EDITGENE today to design your custom CRISPR model for sucrose transport research.
Frequently Asked Questions About sucrose transport
What is sucrose transport?
Sucrose transport is the directed movement of sucrose across membranes via transporters, as defined by GO:0015770.
What genes are involved in sucrose transport?
Key genes include SWEET, SUC2, SUT, and SUS, among others.
How does sucrose transport work in plants?
It involves efflux from source cells, phloem loading, long-distance transport, and uptake into sink tissues.
Why is sucrose transport important for crop yield?
It determines carbon allocation to seeds and fruits, directly affecting yield.
What is the role of SWEET proteins in sucrose transport?
SWEET proteins mediate sucrose efflux from phloem parenchyma, a key step for phloem loading.
How is sucrose transport regulated?
It is regulated by transcription factors like EIN3, developmental cues, and environmental signals.
Can sucrose transport be studied in yeast?
Yes, yeast is a model for sucrose transport and dissimilation, relevant to metabolic engineering.
What methods are used to study sucrose transport?
RNA-seq, proteomics, mutant analysis, and transport assays are common.
How does CRISPR help study sucrose transport?
CRISPR enables knockout, point mutation, knock-in, and overexpression of transporter genes.
What diseases are linked to sucrose transport defects?
In plants, defects cause growth retardation and yield loss; in yeast, poor fermentation.
Conclusion
Sucrose transport (GO:0015770) is a cornerstone of carbon allocation in plants and a critical process in yeast metabolism. Advances in CRISPR and omics technologies continue to unravel the complex regulation and functional diversity of sucrose transporters. Understanding these mechanisms offers opportunities for crop improvement, bioenergy production, and industrial biotechnology.
References
- 1. Chen LQ et al.. 2012. Sucrose efflux mediated by SWEET proteins as a key step for phloem transport.. Science 335(6065):207-11 PMID: 22157085
- 2. Ward JM et al.. 1998. Sucrose transport in higher plants.. Int Rev Cytol 178:41-71 PMID: 9348668
- 3. Wu Y et al.. 2021. Sucrose transporter in rice.. Plant Signal Behav 16(11):1952373 PMID: 34269147
- 4. Kumar R et al.. 2018. Molecular aspects of sucrose transport and its metabolism to starch during seed development in wheat: A comprehensive review.. Biotechnol Adv 36(4):954-967 PMID: 29499342
- 5. Tong C et al.. 2022. Long-distance transport of sucrose in source leaves promotes sink root growth by the EIN3-SUC2 module.. PLoS Genet 18(9):e1010424 PMID: 36129930
- 6. Chen LQ et al.. 2015. Transport of sugars.. Annu Rev Biochem 84:865-94 PMID: 25747398
- 7. Henderson RK et al.. 2021. Energy coupling of membrane transport and efficiency of sucrose dissimilation in yeast.. Metab Eng 65:243-254 PMID: 33279674
- 8. Lu J et al.. 2025. A ray localized vacuolar sucrose transport is required for wood formation in Populus tomentosa.. Plant J 123(2):e70347 PMID: 40726157
