Development of new potato genotypes having disease and stress tolerance and altered nitrogen assimilation by in vitro selection and gene transformation.

Contract nr: OMFB-00070/00 (BIO-085/2000)

Starting date: 01/07/2000

Duration: 48 months

Total cost: 66,7 M HUF

OM contribution: 40 M HUF

Acronym: Potato biotechnology

Background

Potato is one of our most important food crops and an outstanding subject for genetic manipulations as well as for the alloy of new and traditional breeding techniques. However the successful potato production suffers from numerous pathogens and harmful environmental factors. Tissue necrosis caused by the most important infectious plant diseases and abiotic stresses is in close connection of deleterious effects of different reactive oxygen species.

In case the development of plant genotypes resistant to reactive radicals the genotypes could show resistance to pathogens and environmental stresses as well. The production capacity and the nutrient contents of produced tubers are in close correlation to the nitrogen metabolism of the plant. The nitrogen metabolism of the plants can be altered by genetic modification. There is a possibility for the creation of such a more efficient way of ammonia assimilation that can operate in the dark contrary to the plant asparagine synthesis system that utilise glutamine as a substrate. It can have advantageous effects on the increase of the production capacity and the alteration of nutritional content of the plant.

Objectives

1. Development of superoxid (paraquate) resistant potato lines by in vitro selection.
   
   

2. Simultaneous incorporation of catalase (CAT) and superixid-dismutase (SOD) genes into the potato for increase of disease tolerance.
   
   

3. Increase of the production capacity of potato varieties having resistance against different pathogens by the incorporation of bacterial sparagine-synthase (ASN) gene.
   
   

DESCRIPTION

In case the genes of antioxidative enzymes of catalase and superixid-dismutase (CAT and SOD) are highly expressed in plants we my presume that the hydrogen-peroxid developed by the deleterious effects of environmental stresses and infection of pathogens can be neutralised resulting in the missing of tissue necroses. The increase of the expression level of the above two genes can be achieved by in vitro selection and genetic manipulation as well. According to this our goals are the agronomical and pathological characterisation (for resistance against potato late blight and potato virus Y) of the already existing paraquate (superoxid) resistant lines that were developed by in vitro selection and the production and characterisation of lines over expressing the genes CAT and SOD by Agrobacterium mediated genetic transformation.

In case of the lines modified in nitrogen metabolism we are going to investigate the agronomical characters and the changes of nutritional and processing quality (crude protein, amino acid content, cooking and frying quality).

Current status and Results

The in vitro multiplication of paraquate resistant lines selected on the base of preliminary experiments is fulfilled. Their first year comparative experiment under field condition is in progress. Based on the preliminary experiments some of the lines have increased resistance against some pathogens compared to control. Plasmid constructs carrying CAT and SOD genes were developed in Agrobacterium. Transformation experiments are in progress. The multiplication of lines carrying bacterial ASN gene is in progress as well. Till now we have the results of preliminary experiments fulfilled under greenhouse conditions.