title: Distribution of photoperiod-insensitive allele Ppd-A1a and its effect on heading time in Japanese wheat cultivars.
abstract: The Ppd-A1 genotype of 240 Japanese wheat cultivars and 40 foreign cultivars was determined using a PCR-based method. Among Japanese cultivars, only 12 cultivars, all of which were Hokkaido winter wheat, carried the Ppd-A1a allele, while this allele was not found in Hokkaido spring wheat cultivars or Tohoku-Kyushu cultivars. Cultivars with a photoperiod-insensitive allele headed 6.9-9.8 days earlier in Kanto and 2.5 days earlier in Hokkaido than photoperiod-sensitive cultivars. The lower effect of photoperiod-insensitive alleles observed in Hokkaido could be due to the longer day-length at the spike formation stage compared with that in Kanto. Pedigree analysis showed that 'Purple Straw' and 'Tohoku 118' were donors of Ppd-A1a and Ppd-D1a in Hokkaido wheat cultivars, respectively. Wheat cultivars recently developed in Hokkaido carry photoperiod-insensitive alleles at a high frequency. For efficient utilization of Ppd-1 alleles in the Hokkaido wheat-breeding program, the effect of Ppd-1 on growth pattern and grain yield should be investigated. Ppd-A1a may be useful as a unique gene source for fine tuning the heading time in the Tohoku-Kyushu region since the effect of Ppd-A1a on photoperiod insensitivity appears to differ from the effect of Ppd-B1a and Ppd-D1a.
authors.affiliation: NARO Agricultural Research Center , 1-2-1 Inada, Jouetsu, Niigata 943-0193 , Japan ; NARO Institute of Crop Science , 2-1-18 Kannondai, Tsukuba, Ibaraki 305-8518 , Japan ; Okayama University , 1-1-1 Tsushimanaka, Kita, Okayama 700-8530 , Japan.
authors.forename: Masako
authors.initials: M
authors.lastname: Seki
authors.forename: Makiko
authors.initials: M
authors.lastname: Chono
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Nishimura
authors.forename: Mikako
authors.initials: M
authors.lastname: Sato
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Yoshimura
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Matsunaka
authors.forename: Masaya
authors.initials: M
authors.lastname: Fujita
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Oda
authors.forename: Katashi
authors.initials: K
authors.lastname: Kubo
authors.forename: Chikako
authors.initials: C
authors.lastname: Kiribuchi-Otobe
authors.forename: Hisayo
authors.initials: H
authors.lastname: Kojima
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Nishida
authors.forename: Kenji
authors.initials: K
authors.lastname: Kato
keywords: Japanese wheat cultivars; Ppd-A1; heading time; photoperiod response gene; wheat