Distribution of photoperiod-insensitive alleles Ppd-B1a and Ppd-D1a and their effect on heading time in Japanese wheat cultivars

Abstract

The genotypes of photoperiod response genes Ppd-B1 and Ppd-D1 in Japanese wheat cultivars were determined by a PCR-based method, and heading times were compared among genotypes. Most of the Japanese wheat cultivars, except those from the Hokkaido region, carried the photoperiod-insensitive allele Ppd-D1a, and heading was accelerated 10.3 days compared with the Ppd-D1b genotype. Early cultivars with Ppd-D1a may have been selected to avoid damage from preharvest rain. In the Hokkaido region, Ppd-D1a frequency was lower and heading date was late regardless of Ppd-D1 genotype, suggesting another genetic mechanism for late heading in Hokkaido cultivars. In this study, only 11 cultivars proved to carry Ppd-B1a, and all of them carried another photoperiod-insensitive allele, Ppd-D1a. The Ppd-B1a/Ppd-D1a genotype headed 6.7 days earlier than the Ppd-B1b/Ppd-D1a genotype, indicating a significant effect of Ppd-B1a in the genetic background with Ppd-D1a. Early-maturity breeding in Japan is believed to be accelerated by the introduction of the Ppd-B1a allele into medium-heading cultivars carrying Ppd-D1a. Pedigree analysis showed that Ppd-B1a in three extra-early commercial cultivars was inherited from ‘Shiroboro 21’ by early-heading Chugoku lines bred at the Chugoku Agriculture Experimental Station.

Tracking haplotype for QTLs associated with Fusarium head blight resistance in Japanese wheat (Triticum aestivum L.) lineage

“…The geographical distribution of Ppd-D1a alleles in this study corresponded with that of a previous study by Seki et al [36]. In that study, breeding for early maturity in Japan, except in Hokkaido, was possibly accelerated on the basis of the insensitive allele of Ppd-D1 (Ppd-D1a) [36].…”

“…In that study, breeding for early maturity in Japan, except in Hokkaido, was possibly accelerated on the basis of the insensitive allele of Ppd-D1 (Ppd-D1a) [36]. This indicates that the Ppd-D1a allele should be selected because it is a key allele for earliness.…”

Quantitative trait locus analysis for flowering-related traits using two F₂ populations derived from crosses between Japanese common wheat cultivars and synthetic hexaploids

“…The 2DS QTL position was much more closely linked to the Ppd-D1 locus than was the EPS2 centromeric region. The Ppd-D1 dominant allele is frequently found in Japanese wheat cultivars, and contributes to their early flowering phenotype (Seki et al, 2011;Nguyen et al, 2013a). In the Kitanokaori//Ldn/KU-2097 and Norin 61//Ldn/ PI476874 populations, the 2DS QTLs showed high LOD scores and explained large amounts of the phenotypic variation for flowering-related traits (Table 3).…”

“…The vernalization requirement and photoperiodic sensitivity are mainly determined by the Vrn-1 loci on the long arms of homoeologous group 5 chromosomes and the Ppd-1 homoeologous loci on the short arms of group 2 chromosomes, respectively (Murai et al, 2005). Most Japanese wheat cultivars, except those in the Hokkaido area, carry the Ppd-D1a allele on 2DS, which contributes to their early-flowering phenotype (Seki et al, 2011;Nguyen et al, 2013a). The Ppd-D1a mutant allele is photoperiod-insensitive because of a 2-kb deletion upstream of the coding region in a pseudo-response regulator gene (Beales et al, 2007;Nishida et al, 2013).…”

Bridging the gap between marker-assisted and genomic selection of heading time and plant height in hybrid wheat

“…Ppd-D1 encoding a pseudo-response regulator family member (Turner et al, 2005;Beales et al, 2007) is a major regulator of photoperiod response in wheat with also some effect on plant height (Worland et al, 1998), whereas Rht-B1 and Rht-D1 encoding gibberellin response modulators are major regulators of plant height (Peng et al, 1999). The photoperiod-insensitive allele Ppd-D1a promoting early flowering and short growth as well as the gibberellininsensitive alleles Rht-B1b or Rht-D1b promoting semi-dwarf stature are well represented in wheat adapted to temperate zones (Guo et al, 2010;Le Couviour et al, 2011;Seki et al, 2011;Wilhelm et al, 2013a,b). Nevertheless, there is room for additional QTLs, making heading time and in particular plant height interesting model traits for a comparative study of the predictability of combined known major and unknown minor effects.…”