IDENTIFICATION OF RANDOM AMPLIFIED POLYMORPHIC DNA MARKERS LINKED TO BACTERIAL WILT RESISTANCE IN CARNATIONS

Bacterial wilt (caused by Burkholderia caryophylli) is one of the most serious diseases of carnations (Dianthus caryophyllus) in Japan.
This disease is very difficult to control with chemicals once it has occurred.
Breeding of resistant cultivars is considered the optimum strategy to overcoming this disease.
However, it takes over 3 months to determine the resistance of breeding materials by inoculation assays.
DNA markers, which can be identified within days, should therefore be a powerful alternative tool for disease-resistance screening.
Therefore, we decided to identify random amplified polymorphic DNA (RAPD) markers associated with genes controlling wilt resistance in a resistance-segregating population of 134 progeny derived from a cross between ‘Carnation Nou No. 1’ (a carnation breeding line resistant to bacterial wilt) and ‘Pretty Favvare’ (a susceptible cultivar). We screened a total of 465 primers to obtain RAPD markers useful for selecting resistant carnation lines: 11 RAPD markers were linked to genes for resistance to bacterial wilt, and 3 linkage groups were identified by linkage analysis.
The results suggest that at least 3 genes are concerned with resistance to bacterial wilt.
In particular, 4 RAPD markers identified by bulked segregant analysis were linked to a major resistance gene.
These markers should be useful for marker-assisted selection in carnation breeding programs.