Abstract
The mulberry cultivar with unusual red-colored wood, “Sekizaisou,” was discovered in the bushland of Okushiri Island, Hokkaido, Japan, around a century ago. The leaves of this cultivar were used as feed for sericulture on the island for a short duration from 1916. Although propagules of Sekizaisou have been preserved by sequential vegetative propagation in several public research institutes in Japan, Sekizaisou is believed to have already become extinct on the island. Recently, a point mutation in the first exon of the CINNAMYL ALCOHOL DEHYDROGENASE 1 locus in Sekizaisou was identified to be responsible for the change in the color of the wood and the structural alteration of lignin. In this study, we performed genotyping of the allele in nearly 600 mulberry individuals grown naturally on Okushiri Island for the rediscovery of Sekizaisou and its wild relatives. A simple protocol for the detection of the mutant allele using polymerase chain reaction followed by direct Sanger sequencing was applied. Although no individuals with the mutant allele were identified in the present study, our results will provide an insight into the flow of the mutant gene in the natural mulberry population.