Development of a New DNA Marker for Fusarium Yellows Resistance in Vegetables.

In vegetables of L., f. sp. () or f. sp. () cause Fusarium yellows. A resistance gene against () has been identified, and deletion of this gene results in susceptibility (). In contrast, a resistance gene against has not been identified. Inoculation tests showed that lines resistant to were also resistant to , and lines susceptible to were susceptible to . However, prediction of disease resistance by a dominant DNA marker on (Bra012688m) was not associated with disease resistance of in some komatsuna lines using an inoculation test. QTL-seq using four F populations derived from susceptible and resistant lines showed one causative locus on chromosome A03, which covers . Comparison of the amino acid sequence of between susceptible and resistant alleles ( and ) showed that six amino acid differences were specific to susceptible lines. The presence and absence of is consistent with resistance in F populations. These results indicate that is essential for resistance, and changed amino acid sequences result in susceptibility to . This susceptible allele is termed , and a new DNA marker (focbr1-2m) for detection of the allele was developed.