title: Identification of QTLs for fruit quality traits in Japanese apples: QTLs for early ripening are tightly related to preharvest fruit drop.
abstract: Many important apple (Malus × domestica Borkh.) fruit quality traits are regulated by multiple genes, and more information about quantitative trait loci (QTLs) for these traits is required for marker-assisted selection. In this study, we constructed genetic linkage maps of the Japanese apple cultivars 'Orin' and 'Akane' using F1 seedlings derived from a cross between these cultivars. The 'Orin' map consisted of 251 loci covering 17 linkage groups (LGs; total length 1095.3 cM), and the 'Akane' map consisted of 291 loci covering 18 LGs (total length 1098.2 cM). We performed QTL analysis for 16 important traits, and found that four QTLs related to harvest time explained about 70% of genetic variation, and these will be useful for marker-assisted selection. The QTL for early harvest time in LG15 was located very close to the QTL for preharvest fruit drop. The QTL for skin color depth was located around the position of MYB1 in LG9, which suggested that alleles harbored by 'Akane' are regulating red color depth with different degrees of effect. We also analyzed soluble solids and sugar component contents, and found that a QTL for soluble solids content in LG16 could be explained by the amount of sorbitol and fructose.
authors.affiliation: NARO Institute of Fruit Tree Science , 2-1 Fujimoto, Tsukuba, Ibaraki 305-8605 , Japan.
authors.forename: Miyuki
authors.initials: M
authors.lastname: Kunihisa
authors.affiliation: Apple Research Station, NARO Institute of Fruit Tree Science , Shimokuriyagawa, Morioka, Iwate 020-0123 , Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Moriya
authors.affiliation: Apple Research Station, NARO Institute of Fruit Tree Science , Shimokuriyagawa, Morioka, Iwate 020-0123 , Japan.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Abe
authors.affiliation: Apple Research Station, NARO Institute of Fruit Tree Science , Shimokuriyagawa, Morioka, Iwate 020-0123 , Japan.
authors.forename: Kazuma
authors.initials: K
authors.lastname: Okada
authors.affiliation: Apple Research Station, NARO Institute of Fruit Tree Science , Shimokuriyagawa, Morioka, Iwate 020-0123 , Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Haji
authors.affiliation: NARO Agricultural Research Center , 3-1-1 Kannondai, Tsukuba, Ibaraki 305-8666 , Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hayashi
authors.affiliation: NARO Institute of Fruit Tree Science , 2-1 Fujimoto, Tsukuba, Ibaraki 305-8605 , Japan.
authors.forename: Hoytaek
authors.initials: H
authors.lastname: Kim
authors.affiliation: NARO Institute of Fruit Tree Science , 2-1 Fujimoto, Tsukuba, Ibaraki 305-8605 , Japan.
authors.forename: Chikako
authors.initials: C
authors.lastname: Nishitani
authors.affiliation: NARO Institute of Fruit Tree Science , 2-1 Fujimoto, Tsukuba, Ibaraki 305-8605 , Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Terakami
authors.affiliation: NARO Institute of Fruit Tree Science , 2-1 Fujimoto, Tsukuba, Ibaraki 305-8605 , Japan.
authors.forename: Toshiya
authors.initials: T
authors.lastname: Yamamoto
keywords: Malus × domestica; QTL analysis; fruit drop; genetic variance; harvest time; skin color depth; sugar composition