Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Important factors involved in the synthesis of starch in plants

21.10.2005


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:
http://www.basqueresearch.com

More articles from Agricultural and Forestry Science:

nachricht Raiding the rape field
23.05.2018 | Julius-Maximilians-Universität Würzburg

nachricht New technique reveals details of forest fire recovery
17.05.2018 | DOE/Brookhaven National Laboratory

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: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>