| Popis: |
Wheat heading time is genetically controlled by phenology genes including vernalization (Vrn), photoperiod (Ppd) and earliness per se (Eps) genes. Characterization of the existing genetic variation in the phenology genes of wheat would provide breeding programs with valuable information necessary for the development of wheat varieties well-adapted to the local environment and early-maturing traits suitable for double-cropping system. One hundred forty-nine eastern U.S. soft winter (ESW) and 32 Korean winter (KW) wheat varieties were characterized using molecular markers for Vrn, Ppd, Eps and reduced-height (Rht) genes, and phenotyped for heading date (HD) in eastern U.S. region. The predominant alleles in ESW and KW varieties were the Ppd-A1b, Ppd-B1b and Ppd-D1a alleles at the Ppd-1 loci and the vrn-B1-Neuse and vrn-D3b alleles at the Vrn-B1 and Vrn-D3 loci. A single copy of the vrn-A1 allele was observed in 81.3% of KW varieties, but only in one ESW variety. The genetic variations for HD of ESW varieties were largely contributed by the Ppd-B1, Ppd-D1 and Vrn-D3 loci. The Rht-D1 locus largely contributed to the genetic variation for HD of KW varieties. A phenology gene profile at four major loci (Ppd-B1b/Ppd-D1a/vrn-A1(three or more copies)/vrn-D3b) was predominantly observed in 52.8% of ESW varieties, while 76.7% of KW varieties carried one of these two phenology gene profiles: Ppd-B1b/Ppd-D1a/vrn-A1(one copy)/vrn-D3a or Ppd-B1b/Ppd-D1a/vrn-A1(one copy)/vrn-D3b. KW varieties headed on average 14 days earlier than ESW varieties in each crop year, largely due to the presence of a single copy of the vrn-A1 allele in the former. |
