Understanding the flowering gene complex in hexaploid spring wheat (Triticum aestivum L.)

• Author / Creator

  Kamran, Atif

• Understanding the flowering gene complex in bread wheat is important to utilize the maximum production potential in a time-limited growing season. Vernalization (Vrn), photoperiod (Ppd) and earliness per se are the three genetic constituents of the flowering gene complex. A series of experiments were conducted to explore the role of each genetic constituent in Canadian spring wheat germplasm. The first experiment revealed vernalization and photoperiod gene frequency and effects in Canadian germplasm released between 1885 and 2008. Vernalization insensitive Vrn-A1a is the most frequent allele in the Canadian hard red spring class and Vrn-B1 is more frequent in Canadian soft white spring class. The photoperiod sensitive allele (Ppd-D1) is being replaced with the insensitive allele, Ppd-D1a, in all modern Canadian germplasm. An overall analysis of the data for the CWRS class revealed an average reduction of 0.04 days/year in maturity and an increase of about 8 kg/ha/year in grain yield. A second study was conducted on the Cutler × AC Barrie population to map and characterize the earliness per se QTL. Three QTLs of earliness per se affecting days to flowering and maturity were mapped on chromosomes 1B (QEps.dms-1B1 and QEps.dms-1B2) and 5B (QEps.dms-5B1). Two grain yield QTLs were mapped on chromosome 5B. The photoperiod insensitive allele Ppd-D1a interacted in an additive fashion with QTLs for flowering and maturity times. The earliness per se QTL QFlt.dms-5B.1 together with Ppd-D1a can induce earlier flowering and could help to elongate grain filling duration for higher grain yields. A comparative study of Vrn alleles suggests that the presence of Vrn-D1 along with Vrn-A1a and Vrn-B1 confers higher grain yield with similar maturity compared to all other Vrn gene groups in soft white spring wheat and we suggested the inclusion of Vrn-D1 allele in elite Canadian germplasm, which has been overlooked in the past. In a final study we found that early flowering and maturity conferred by insensitive vernalization alleles Vrn-A1a and/or Vrn-B1 has not conferred any yield advantage under organic conditions. The results also revealed that there is significant genotype × environment interaction and breeding for organic production should be practiced under organic conditions.

• Subjects / Keywords

  • Wheat
  • Earliness per se
  • Maturity
  • Photoperiod
  • Vernalization
  • Flowering

• Graduation date

  Spring 2014

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3QD6S

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.