Screening of the breeding materials from genetic resources lacking anthocyanin for the development of purple-fleshed sweetpotato

Reddish purple-fleshed sweetpotato (RFSP) has been recently developed in Japan; its anthocyanidin profile is dominated by pelargonidin, whereas purple-fleshed sweetpotato (PFSP) primarily contains peonidin and cyanidin. The reddish purple color of RFSP is a recessive phenotype associated with flavonoid 3’-hydroxylase (F3’H) activity. Considering the limited availability of RFSP breeding materials, in this study, we aimed to identify promising RFSP breeding materials from genetic resources lacking anthocyanin in their flesh. Six parents with white or yellow flesh color were evaluated by crossing F1 plants with RFSP clones. RFSP clones served as testers for evaluating F3’H activity of parents. F1 plants from all six crosses had purple flesh. However, F1 plants derived from ‘Konamirai’ had a higher pelargonidin percentage compared with the other five crosses. These results suggest that Konamirai is a promising parent to broaden the genetic basis of PFSP breeding. Subsequently, to investigate whether Konamirai is an effective material, a progeny ‘Kyukei22242-3’ that contains purple flesh, with pelargonidin comprising approximately 20% of the anthocyanin content, was crossed with RFSP. The pelargonidin percentage and other agronomic traits, including dry matter and starch contents, of F1 plants were evaluated. F1 plants with varying flesh color were segregated into two classes, with the RFSP:PFSP ratio of 16:19. RFSP progenies were highly abundant in the grandchild generation of Konamirai. F1 plants exhibited normal distributions for both dry matter and starch contents. Therefore, elite clones with both reddish purple flesh and high dry matter and starch contents existed in Konamirai’s grandchild generation.