Phytophthora resistance in azalea

General introduction

The aim of this project is to detect susceptibility to Phytophthora citricola in early-stage azalea breeding to support breeding of resistant cultivars. To discriminate resistant plants from susceptible ones, a bio-assay is used on all candidate cultivars. Phytophthora citricola is a fungal pathogen that can cause great damage to the azalea crop. Disease susceptibility is cultivar dependent, thus plants can be bred for increased disease resistance.

Research approach

A bio-assay is developed that differentiates between susceptible and less susceptible genotypes. Rooted cuttings are made and the cutting face is infected with zoospores. The zoospores enter the plant. The cuttings start to brown from the cutting face downward. During the azalea breeding process, this bio-assay is applied several times to all genotypes subject to selection. The results are compared to cultivars with known susceptibility or resistance. All genotypes that score badly are eliminated from the breeding program.

Relevance/Valorisation

Azaleas are the most important ornamental product in Belgium, with the main production area in the province of East Flanders. In 2010 the total azalea production value reached 50.1 million euros. An EU Directive requires that all crops must be cultivated based on the principles of integrated pest management (IPM). This involves a combination of pest control techniques with reduced environmental impact. Breeding for increased disease resistance is an excellent contribution to IPM.