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 Plasma-zapping process could yield trans fat-free soybean oil product
02.12.2016 | Purdue University

nachricht New findings about the deformed wing virus, a major factor in honey bee colony mortality
11.11.2016 | Veterinärmedizinische Universität Wien

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: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

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

14.10.2016 | Event News

 
Latest News

NTU scientists build new ultrasound device using 3-D printing technology

07.12.2016 | Health and Medicine

The balancing act: An enzyme that links endocytosis to membrane recycling

07.12.2016 | Life Sciences

How to turn white fat brown

07.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>