Cultivation

Potatoes are grown worldwide in regions with moderate to subtropical climates. In 2005, altogether 322 millions tons of potatoes were harvested in 157 countries. Over half of the world's production was produced by China, Russia, India, Ukraine, the USA, Germany and Poland.

Utilisation

In Germany over half of the potato harvest lands directly or processed on the table; only about 5% are used as animal feed, and approximately one third is utilised in the starch industry.

Foodstuffs and ingredients

The consummation of potatoes in Germany has a long tradition. Around 1900 every German was reckoned to eat on average 285 kg per year; today this is now only just under 70 kg per year. Of this about 45% is in the form of industrially prepared products:

• purée,chips, snacks and convenience food.

• potato starch is the basis of numerous food components (thickening and binding agent) and is the basic material for the process producing sugar from starch, from which many ingredients and supplements emerge.

Renewable primary products, energy crops

• 40% of the starch is processed in the non-food area:
  in particular in adhesives and lubricants, in paper and corrugated paper production, as packaging and as building materials.
• Potato starch can be used to produce energy through conversion to ethanol and methane.

Gene technology: aims of research and development

Agronomic traits

Resistance against pathogens

• Fungal resistance: e.g. against the pathogen causing potato late blight (Phytophtora infestans), which effects leaves, stems and tubers. This fungus causes harvest losses of around 20% and is very difficult to combat. Usually chemical and other fungicides are employed.

• Virus resistance

• Bacterial resistance against blackleg and bacterial soft rot

Resistance to pests

• Insect resistance: e.g. against the Colorado potato beetle, through transfer of genes for Bt toxins or through plant repellents such as lectins.

Weed control

• Herbicide tolerance against the active ingredient glyphosate

Adaptation to climate and location factors

• Drought and cold resistance

• Salt tolerance

Quality traits

Modified composition of components

• Carbohydrate metabolism: modification of the starch or sugar composition of potatoes to influence the taste, to reduce the brown blotchiness or to improve the browning effect on frying or roasting.

Enrichment with health-promoting components such as:

• zeaxanthin, acarotenoid that may play a role in preventing retina degeneration.

• fructans, e.g. inulin (functional foods)

• lysine, an essential amino acidin man

• beta-carotene, a precursor of vitamin A

Renewable primary products

Modified composition of ingredients

• Potatoes form starchin two different forms: amylose and amylopectin. The starch industry requires either amyloseor amylopectin depending on the application. Amylopectin is particularly of interest for many industrial processes (e.g. basic material for foils, paste, packaging), but also for certain starch ingredients. Using gene technology, potatoes can be established that exclusively contain amylopectin (or amylose). The separation of these two types of starch, which at present is carried out in complex processes, would no longer be necessary.

• Genetically modified plants produce Cyanophycin, which can be used to synthesise the biodegradable plastic poly-aspartate. Cyanophycin, a storage protein is naturally produced by Cyanobacteria.

Production of pharmaceutically active substances

• Molecular pharming: utilisation of gene-modified potatoes as a system for producing active pharmaceutical ingredients such as vaccines has up to now only been carried out in research.

Basis research

• The Max-Planck-Institute for Molecular Physiology of Plants in Golm is undertaking research on potatoes with a modified stomatal density. In plants gas exchange takes place via the stomata, which represents a limiting factor for metabolism. Conditions under which an increased stomatal density can improve starch production and tuber growth are being examined in field trials.

Field trials with GM potatoes

Utilisation of GM potatoes