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Title: Optimizing Energy Efficiency of Plants: Quantitative Analysis of Carbon Flux

Abstract

The efficiency in harvesting light energy is essential for both crop and feedstock productivity. Key targets for optimization of energy efficiency include energy capture, conversion, translocation and storage. Surprisingly little is known about the mechanisms of carbon allocation and the communication between source and sink. We surmise that regulatory networks that coordinate carbon partitioning and allocation might be control points and thus suitable for optimization by engineering. At a first step towards identifying such regulatory networks, our lab identified key players in missing steps of allocation, specifically cellular sugar uptake (SUT family, founding members identified by my team) and cellular efflux carriers (SWEET superfamily, founding members identified by my team). In plants, both classes of transporters are encoded by multigene families. We show that specific subsets of SWEETs serve critical roles in cellular sucrose efflux in the leaf for phloem loading, in seeds for seed filling, as well as in nectar section and vacuolar storage; similarly SUTs play critical roles in cellular uptake during phloem loading and seed filling. Access to the plant SWEETs provided the clues needed for identifying novel bacterial and human sugar transporters. Moreover, we found that pathogens hijack SWEETs to access the plants energy resources. Inmore » contrast to SUTs, which are predominantly proton symporters, SWEETs appear to function as facilitators, and thus must be tightly regulated to prevent spillover of carbon into cell walls. One of the key goals of this project was to identify such carriers, characterize the role of key members in carbon allocation. To decrypt the biological circuits we need novel diagnostic tools that, analogous to oscilloscopes in electrical engineering of circuit boards, allow us to quantify fluxes; here by monitoring sugars. Such probes can provide crucial information on systems properties such as metabolic impedance. To measure steady state metabolite levels with minimal invasive methods, and to develop impedance measurements in vivo, we constructed and optimized a set of probes, namely Förster Resonance Energy Transfer (FRET) nanosensors for glucose and sucrose. The probes monitor the concentration of a specific metabolite with high temporal resolution, and, since encoded genetically, can be targeted to specific cells or even specific cellular compartments and thus obtain measurements with cellular and subcellular resolution. We also developed a new platform for monitoring such sensors in vivo, the RootChip.« less

Authors:
ORCiD logo [1]
  1. Carnegie Inst. of Science, Stanford, CA (United States); Heinrich Heine Univ., Duesseldorf (Germany)
Publication Date:
Research Org.:
Carnegie Inst. of Washington, Washington, DC (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1439964
Report Number(s):
DOE-CIW-15542
DOE Contract Number:  
FG02-04ER15542
Resource Type:
Technical Report
Resource Relation:
Related Information: Publication
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; carbon allocation; transporter; sucrose; phloem; seed

Citation Formats

Frommer, Wolf B. Optimizing Energy Efficiency of Plants: Quantitative Analysis of Carbon Flux. United States: N. p., 2018. Web. doi:10.2172/1439964.
Frommer, Wolf B. Optimizing Energy Efficiency of Plants: Quantitative Analysis of Carbon Flux. United States. doi:10.2172/1439964.
Frommer, Wolf B. Sun . "Optimizing Energy Efficiency of Plants: Quantitative Analysis of Carbon Flux". United States. doi:10.2172/1439964. https://www.osti.gov/servlets/purl/1439964.
@article{osti_1439964,
title = {Optimizing Energy Efficiency of Plants: Quantitative Analysis of Carbon Flux},
author = {Frommer, Wolf B.},
abstractNote = {The efficiency in harvesting light energy is essential for both crop and feedstock productivity. Key targets for optimization of energy efficiency include energy capture, conversion, translocation and storage. Surprisingly little is known about the mechanisms of carbon allocation and the communication between source and sink. We surmise that regulatory networks that coordinate carbon partitioning and allocation might be control points and thus suitable for optimization by engineering. At a first step towards identifying such regulatory networks, our lab identified key players in missing steps of allocation, specifically cellular sugar uptake (SUT family, founding members identified by my team) and cellular efflux carriers (SWEET superfamily, founding members identified by my team). In plants, both classes of transporters are encoded by multigene families. We show that specific subsets of SWEETs serve critical roles in cellular sucrose efflux in the leaf for phloem loading, in seeds for seed filling, as well as in nectar section and vacuolar storage; similarly SUTs play critical roles in cellular uptake during phloem loading and seed filling. Access to the plant SWEETs provided the clues needed for identifying novel bacterial and human sugar transporters. Moreover, we found that pathogens hijack SWEETs to access the plants energy resources. In contrast to SUTs, which are predominantly proton symporters, SWEETs appear to function as facilitators, and thus must be tightly regulated to prevent spillover of carbon into cell walls. One of the key goals of this project was to identify such carriers, characterize the role of key members in carbon allocation. To decrypt the biological circuits we need novel diagnostic tools that, analogous to oscilloscopes in electrical engineering of circuit boards, allow us to quantify fluxes; here by monitoring sugars. Such probes can provide crucial information on systems properties such as metabolic impedance. To measure steady state metabolite levels with minimal invasive methods, and to develop impedance measurements in vivo, we constructed and optimized a set of probes, namely Förster Resonance Energy Transfer (FRET) nanosensors for glucose and sucrose. The probes monitor the concentration of a specific metabolite with high temporal resolution, and, since encoded genetically, can be targeted to specific cells or even specific cellular compartments and thus obtain measurements with cellular and subcellular resolution. We also developed a new platform for monitoring such sensors in vivo, the RootChip.},
doi = {10.2172/1439964},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2018},
month = {6}
}

Works referenced in this record:

SWEET11 and 15 as key players in seed filling in rice
journal, February 2018

  • Yang, Jungil; Luo, Dangping; Yang, Bing
  • New Phytologist, Vol. 218, Issue 2
  • DOI: 10.1111/nph.15004

Mechanism of Substrate Translocation in an Alternating Access Transporter
journal, March 2017


Impaired phloem loading in zmsweet13a,b,c sucrose transporter triple knock-out mutants in Zea mays
journal, February 2018

  • Bezrutczyk, Margaret; Hartwig, Thomas; Horschman, Marc
  • New Phytologist, Vol. 218, Issue 2
  • DOI: 10.1111/nph.15021

Seed filling in domesticated maize and rice depends on SWEET-mediated hexose transport
journal, November 2015

  • Sosso, Davide; Luo, Dangping; Li, Qin-Bao
  • Nature Genetics, Vol. 47, Issue 12
  • DOI: 10.1038/ng.3422