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Title: Vernalization duration requirement in soft winter wheat is associated with variation at the vrn-B1 locus

Author
item GUEDIRA, MOHAMMED - North Carolina State University
item MALONEY, PETER - North Carolina State University
item MURPHY, J - North Carolina State University
item XIONG, MAI - North Carolina State University
item Marshall, David
item JOHNSON, JERRY - University Of Georgia
item HARRISON, STEVEN - Louisana State University
item Brown-Guedira, Gina

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/20/2014
Publication Date: 6/23/2014
Citation: Guedira, M., Maloney, P., Murphy, J.P., Xiong, M., Marshall, D.S., Johnson, J., Harrison, S., Brown Guedira, G.L. 2014. Vernalization duration requirement in soft winter wheat is associated with variation at the vrn-B1 locus. Crop Science. 54:1960-1971.

Interpretive Summary: Understanding flowering time in winter wheat is important in breeding better wheat varieties. The cumulative amount of time a germinated seed grows at temperatures below 40 degrees F is known as the vernalization period of a wheat plant. Once that vernalization period is met, then the plant responds to longer day lengths in the late winter – early spring of each year, resulting in the plant’s flowering and subsequent seed production. We analyzed the progeny of a cross between a late-flowering variety, ‘NC-Neuse’ and an early-flowering variety, ‘AGS 2000’, and found a genetic factor related to early-flowering. We can now develop a molecular marker associated with this genetic factor and use it in marker-assisted selection for early-flowering plants.

Technical Abstract: In winter wheat (Triticum aestivum L.), the timing of flowering initiation is governed by the action two main environmentally controlled group of genes; vernalization that defines a plant’s requirement for a prolonged exposure to cold temperatures and photoperiod sensitivity defining the need for a long days to initiate floral transition. Genetic variation in both vernalization and photoperiod sensitivity allow wheat to be grown in extremely diverse environments. In this study we evaluated heading date in greenhouse and field for a RIL population from the cross between the winter wheat cultivars NC-Neuse (late) and AGS 2000 (early) that are adapted the U.S. Mid-Atlantic and Southeastern regions, respectively. Heading dates of 130 RIL and the parents were evaluated in the greenhouse after being vernalized for four or eight weeks then grown under long photoperiod. Although both cultivars have recessive winter alleles at the three VRN1 loci, we identified a QTL for heading date after four weeks vernalization designated Qvdr.nc-5BL in the region of chromosome 5B where VRN-B1 resides. This region did not have a significant effect on heading date in plants that were vernalized for 8 weeks or in the field in North Carolina during 2011. However, Qvdr.nc-5BL had a large effect on winter dormancy release and heading date when the population was evaluated in the field at locations in North Carolina, Georgia and Louisiana during 2012 and North Carolina in 2013. Other regions, including the PPD-B1 locus, were determined to have smaller effects on heading date in environments where Qvdr.nc-5BL was not significant. Interrogation of a SNP between AGS 2000 and NC-Neuse in the first intron of the vrn-B1 placed the VRN-B1 locus under the Qvdr.nc-5BL peak, indicating that VRN-B1 or a closely linked locus is important in the regulation of winter wheat development.