Du
01 May 2013
au
30 April 2016

GEREPHYTI

Improving and managing potato resistance to Phytophthora infestans in order to develop ecologically intensive agriculture

Context

Potatoes are a major field crop in Belgium (70,000 ha). Potato growing is also expanding rapidly in Wallonia, mainly in silty areas and in Condroz (more than 10,000 ha added in five years).

Potato blight is a major crop threat. The International Potato Center (CIP) estimates overall production losses worldwide to the disease at 15%. Attempts to improve potato blight resistance have been unsuccessful, being mainly based on using major resistance genes (11 R genes) occurring in Solanum demissum, which are generally bypassed by pathogen populations. Moreover, in countries where intensive farming is practiced, fungicides have for too long been regarded as the obvious way to control the disease. In the case of Belgium, more than 60% of the land under potatoes is still dedicated to growing Bintje. This variety is highly susceptible to blight, requiring frequent fungicide spraying (up to 18 treatments per growing season). The situation is generally not much better as regards the other blight-susceptible varieties grown in Belgium (Charlotte, Fontane, Lady Rosetta, Première, etc.).

Large-scale pesticide application to agricultural crops is increasingly incompatible with European decisions aimed at improving environmental protection. Decision 1600/2002/EC requires Member States to produce a plan for reducing pesticide use, and Directive 2009/128/EC requires Member States to develop integrated pest management. In the case of the potato, these specific aims will only be achieved if research is directed at developing and using more blight-tolerant varieties.

New initiatives are now emerging in response to this trend, in particular identifying resistance genes in wild Solanum species such as S. bulbocastanum, S. microdontum, S. berthaultii, S. stoloniferum and S. venturii and using them in breeding programs. These new resistance genes are introduced in two ways: conventional breeding and genetic transformation. As a result of developments in biotechnology, new strategies are emerging for reducing the risks of bypassing resistance, in particular by stacking different genes isolated from different species and inserted into plasmids, which are then introduced into the genome of the cultivars by genetic engineering. This method of artificially introducing resistance genes occurring in the Solanum genus that have retained their natural regulatory sequences (promoters, terminators, etc.) is called cisgenesis, in contrast to the usual transgenesis technique which uses desirable genes occurring in genera other than Solanum that are established in synthetic plasmid constructs. Although endorsed by the industry, this approach sometimes runs up against the misgivings of some sections of society.

Also, some varieties with outstanding and, apparently, more sustainable resistance levels have appeared on the market in the last few years. Examples include Sarpo Mira and Bionica, created by a lengthy process (more than 40 years) of conventional breeding from wild Solanum species. These comprise new germplasm that can be used in conventional marker-assisted selection programs targeting these genes to increase resistance levels in commercial varieties with more favorable agricultural and use characteristics.

Developing marker-assisted breeding techniques also enables detection of the effective presence of desirable genes and their segregation in a population derived from crosses at an earlier stage, thus considerably lessening the workload involved in potatobreeding.

Objectives

The general aim of the project is to obtain improved clones/varieties with a view to sustainable late blight resistance. The proposed route to improving variety behavior involves using conventional crossing methods but tapping the potential offered by new techniques (cisgenesis, marker-assisted selection) and new germplasm (new R genes). Through the new resources thus created, the project will serve to intensify and develop the potato breeding program begun by the Life Sciences Department in 2005.

The project fits perfectly with CRA-W’s stated aims for the next few years, in particular the aim of developing research towards ecologically intensive agriculture. Innovations aimed at ensuring sustainable food production, the efficient use of inputs, integrated and dynamic management of inputs, adaptation to changes – all these aims will undoubtedly be furthered by creating new, late blight resistant or more tolerant varieties.

Expected results

The project aims to produce new potato varieties with improved potato late blight (Phytophthora infestans) resistance characteristics. The GEREPHYTI project will help to develop and focus the potato breeding work already undertaken by the Life Sciences Department using conventional crossing methods, by :

  1. refining and developing cisgenesis transformation techniques in order to form a pool of parents having one or more stable resistance genes found in the Solanum genus,
  2. developing marker-assisted selection,
  3. creating a parent collection with confirmed resistance genes for use in the crossing program.

Funding

  • CRA-W - Moerman funds

Team

Vincent CESARJean-Pierre GOFFARTYordan MUHOVSKIAlice SOETE