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.