Allele dosage–dependent selection of recessive F3 ’ H allele homozygote altered anthocyanin composition in sweetpotato

To change the major anthocyanin in the storage roots of sweetpotato ( Ipomoea batatas ) from purplish cyanidin derivatives to reddish pelargonidin derivatives, the dosage of a recessive allele in the F3 ’ H gene locus was enriched by successive crossing and allele dosage estimation. A putative recessive allele of the F3 ’ H gene, named f3 ’ h tm , was found in the cultivar Tanegeshimamurasaki and contained a 57-bp deletion causing a premature stop codon. Starting with the parents having a simplex f3 ’ h tm allele, plants considered to be homozygous with f3 ’ h tm were obtained in the F 4 generation. The storage roots and other pigmented tissues of the homozygous plants showed a reddish color, whereas the original parents or F 4 plants without homozygous f3 ’ h tm were purplish. More than approximately 90% of the anthocyanins in the storage roots of plants with homozygous f3 ’ h tm were pelargonidin derivatives. These results suggest that allele dosage–dependent selection is also possible in autohexaploid crops to develop mutants with novel phenotypes. In addition, the obtained plants with homozygous f3 ’ h tm can be important materials for breeding sweetpotato cultivars for pelargonidin production.