A RAPD-derived STS marker is linked to a bacterial wilt (Burkholderia caryophylli) resistance gene in carnation

Bacterial wilt caused by Burkholderia caryophylli is one of the most important and damaging diseases of carnations ( Dianthus caryophyllus) in Japan. We aimed to identify random amplified polymorphic DNA ( RAPD) markers associated with the genes controlling bacterial wilt resistance in a resistance-segregating population of 134 progeny plants 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 505 primers to obtain RAPD markers useful for selecting resistant carnation lines: 8 RAPD markers identified by bulked segregant analysis were linked to a major resistance gene; of these, WG44-1050 had the greatest effect on resistance to bacterial wilt. A locus with large effect on bacterial resistance was mapped around WG44-1050 through QTL analysis. The RAPD marker WG44-1050 was successfully converted to a sequence-tagged site (STS) marker suitable for marker-assisted selection (MAS). Five combinations of primers were designed for specific amplification of WG44-1050. In addition, the STS marker we developed was useful and reliable as a selection marker for breeding for resistance to bacterial wilt, using a highly resistant wild species, D. capitatus ssp. andrzejowskianus and a resistant line, 'Carnation Nou No. 1', as breeding materials.