QTL cloning at University of California, Davis

	Co-PI: Jorge Dubcovsky jdubcovsky@ucdavis.edu
	Ph.D. student: Saarah Kusay snkuzay@ucdavis.edu

Saarah will focus on a QTL for number of spikelets per spike (SPS) located on chromosome arm 7AL (160-165 Mb). This QTL was identified in five environments in two GWAS studies, one including 875 spring wheat lines and the other 240 spring / photoperiod-insensitive advanced breeding lines.

The QTL was validated in the Berkut x RAC875 NAM population (LOD 3.3, 20% of variation explained, and heritability 0.88). On average, lines carrying the Berkut allele have 2.4 more spikelets per spike than those carrying the RAC875 allele:

We have already identified two F₆ lines from this NAM population that are heterozygous for the QTL region. Using near isogenic F_6:2 plants segregating for the target region we were able to validate the differences in spikelet number per spike between Berkut and RAC875 in the greenhouse. The F_6:2 plants heterozygous for the target region were used to generate >1,000 F_6:3 seeds segregating for the target region.

Other QTLs in the same position were detected in segregating populations from the CO, KS, MN and MT programs, supporting the value of this QTL as a target for positional cloning. Saarah will coordinate collaborations among these programs to identify and deploy this gene.