Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Important factors involved in the synthesis of starch in plants


The classic model for explaining the biosynthesis of starch in plant leaves has been seriously called in to question. While to date the accepted belief has been that starch biosynthesis is produced solely in the chloroplast, biologist Nora Alonso Casajús’ PhD provides evidence to show that the greatest part of the precursor molecule in starch biosynthesis – known as ADPG – accumulates in the cytosol of the plants. This finding has meant a great advance in the race to obtain vegetables that can produce large quantities of starch, a substance the annual production of which is about a thousand million tonnes and which has become an essential raw material in multiple sectors of modern industry such as biofuels or biodegradable plastics.

The thesis, entitled, Factors involved in the regulation of starch and glycogen production in plants and bacteria was recently defended the Public University of Navarra’s Institute of Agrobiotechnology.

Biosynthesis of starch

According to the classical model for explaining the biosynthesis of starch, sucrose and starch are final products of two unidirectional routes that take place in the cytosol and the chloroplast respectively. Moreover, this model takes it that the ADPglucose pyrophosphorylase (AGP) is the only enzyme responsible for the biosynthesis of the starch precursor, ADPglucose (ADPG). Over the last few years there have been numerous indications suggesting the involvement of another enzyme, sucrose syntase (SuSy), in the production of the cytosolic ADPG needed for the synthesis of starch.

To analyse which of the models was the correct one this biologist determined the subcellular location of the ADPG linked to the starch biosynthesis, the tool used being plants that superexpress bacterial ADPG hydrolase, both in the cytosol and in the chloroplast.

With the research results, it has been possible to conclude that, contrary to that proposed in the classical model, most ADPG linked to starch biosynthesis is concentrated in the cytosol. This cytosolic location of the ADPG suggests, moreover, that the enzyme responsible for the biosynthesis of the ADPG is not the plastidial AGP, but the sucrose syntase. This is why the researcher went on to produce and characterise plants that superexpressed SuSy.

Her research concluded, primarily, that the ADPG produced by SuSy is linked to the biosynthesis of starch; secondly, that SuSy has significant control over this biosynthesis process and, thirdly, that it is SuSy and not the AGP that catalyses the production of ADPG that accumulates in the leaves.

Glycogen in bacteria

If starch is the main form of energy reserve for the plants, glycogen is the essential way in which bacteria accumulate energy. Nevertheless, according to Nora Alonso, “information about the possible involvement of glycogen in multiple metabolic processes is scarce and still fragmented”, the reason why part of the PhD was given over to study how the breakdown of the bacterial glycogen comes about and how the biology of this polyglucane functions. Thus, it was shown that glycogen acts as a “a carbon capacitor that helps to preserve osmotic homeostasis in the bacteria".

The possible involvement of glycogenphosphorylase (GlgP) in the breakdown of glycogen has, until now, been based on indirect evidence of a biochemical nature, as bacteria with altered levels of GlgP have never been produced or characterised. Nevertheless, in this PhD work the production and characterisation of bacteria with altered levels of GlgP have enabled an elucidation of the fundamental role of this enzyme, both in the breakdown of the glycogen and in the production of precursors for the synthesis of maltodextrines.

Moreover, Nora Alonso concluded that the control that GlgP has on the breakdown of glycogen and on the biosynthesis of maltodextrines is notably different for different strains of E. coli. Finally, Ms Alonso has shown that the GlgP acted during the process of accumulation of glycogen.

Garazi Andonegi | alfa
Further information:

More articles from Agricultural and Forestry Science:

nachricht Forest Management Yields Higher Productivity through Biodiversity
14.10.2016 | Technische Universität München

nachricht Farming with forests
23.09.2016 | University of Illinois College of Agricultural, Consumer and Environmental Sciences (ACES)

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Ice shelf vibrations cause unusual waves in Antarctic atmosphere

25.10.2016 | Earth Sciences

Fluorescent holography: Upending the world of biological imaging

25.10.2016 | Power and Electrical Engineering

Etching Microstructures with Lasers

25.10.2016 | Process Engineering

More VideoLinks >>>