Co-PI: Stephen Pearce
Stephen.Pearce@colostate.edu

Co-PI: Scott Haley
Scott.Haley@colostate.edu

Co-PI: Pat Byrne
Patrick.Byrne@colostate.edu

PhD student: Andrew Katz

Andrew will be working to characterize a QTL for spikelet number on chromosome arm 6BL (503Mb) identified from a GWAS on the Hard Winter Wheat Association Mapping Panel. This QTL was validated in an F_5:6 Platte/CO940610 RIL population (n=224) during the 2016-2017 field season. The 6BL QTL Platte allele showed a positive effect of 0.39 spikelets per spike (R²=11.8, P < 0.0001).  The RIL population is also segregating for three alleles with known effects on spikelet number; VRN-D3a/b, PPD-B1a/b, and a 7AL QTL under investigation at UC Davis.

For the 2018-2019 field season, the F_5:7 Platte/CO940610 RIL population (n=218) was planted to validate the effect of the 6BL QTL on spikelet number. Eight F_5:6 heterogeneous inbred families (n=96 individuals per family) derived from the F_4:5 Platte/Co940610 RIL population were planted to screen for critical recombinants for fine-scale mapping and to test the interactions between the 6BL QTL and the known spikelet number alleles. To introgress the 6BL QTL into elite materials, we have generated F₁ seed from crosses between Platte (carrying the favorable 6BL and 7AL alleles) and three high-biomass CIMMYT lines (Bonsu, Nadi, and Mucuy) and commenced crosses with two Colorado advanced breeding lines (Monarch and CO13D1479) that carry the 6BL allele for low spikelet number.