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Sucrose transporter1 functions in phloem loading in maize leaves
Thomas L Slewinski1, Robert Meeley, David M Braun
1Department of Biology, Pennsylvania State University, 208 Mueller Lab, University Park, PA 16802, USA.
Journal of Experimental Botany
|February 3, 2009
Summary
Maize SUT1 is essential for transporting sucrose from leaves to other plant parts. Mutants show carbohydrate buildup, stunted growth, and delayed development, confirming SUT1
Area of Science:
- Plant Physiology
- Molecular Biology
- Agricultural Science
Background:
- Sucrose transport is vital for plant growth, relying on sucrose transporters (SUTs) in phloem loading.
- While SUT1 is known in dicots, its role in monocot phloem loading, like in maize, remained unclear.
Purpose of the Study:
- To investigate the biological function of the SUT1 gene in maize (Zea mays) phloem loading.
- To determine if maize SUT1 plays a role in sucrose export from source leaves.
Main Methods:
- Isolation and characterization of a maize sut1 mutant.
- Phenotypic analysis of sut1 mutants, including growth, development, and carbohydrate accumulation.
- Experimental manipulation of phloem transport (cold-girdling) and radioactive sucrose export assays.
Main Results:
- sut1 mutants exhibited hyperaccumulation of carbohydrates in mature leaves, leading to chlorosis and premature senescence.
- Mutants displayed reduced stature, altered biomass allocation, delayed flowering, and impaired tassel development.
- Cold-girdling mimicked sut1 mutant phenotypes, and radioactive sucrose export assays confirmed significantly reduced sucrose export in mutants.
Conclusions:
- Maize SUT1 is crucial for efficient sucrose phloem loading and export from leaves.
- Disruption of SUT1 function severely impacts plant growth, development, and carbon partitioning in maize.
- These findings clarify the role of SUT1 in monocot phloem loading, distinct from some other monocots like rice.
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