Fine Mapping Coincident QTL for Multiple Traits Linked with Gpc1 on Chromosome 6H of Barley.

Barley with bright kernels (low kernel discoloration or KD level), low mycotoxin deoxynivalenol accumulation, resistance to Fusarium head blight (FHB), net blotch and bacterial leaf streak, relatively low grain protein (GP) content (115 - 135 g/kg), and good agronomic traits (high yield, low lodging, low stem breakage, desirable heading and senescencing dates) are desirable for the malting and brewing industries. Quantitative trait loci (QTL) studies and other genetic evidence have associated these traits with a region of chromosome 6H near bin 6 of barley. In addition, this coincident QTL 6H region is orthologous to Gpc-B1 influencing protein concentration in wheat. Unfortunately, some of these traits are in unfavorable associations posing a challenge for breeding. For example, the cultivar Chevron has good FHB and KD resistances, but high (undesirable) GP and poor agronomic traits; while the cultivar Karl has low GP but discolored kernels. Whether the genetic associations among these traits are due to linkage (“breakable” associations) or pleiotropy (“unbreakable” associations) remains unknown. We developed a mapping population comprised of 101 possible recombinants using a near-isogenic BC₅ parent carrying a segment of Chevron spanning this 6H region in the background of the commercial cultivar Lacey. The objectives of this project are to 1) validate/determine the associations of the above traits at this 6H region; 2) fine map the 6H region for the above traits; and 3) recover, if possible, recombinants with favorable associations. Genotype-by-sequencing will be implemented to give dense marker coverage in the target region. Each of the 11 traits indicated above was evaluated in at least two field trials in 2015. These data will be used to conduct analysis of variance and QTL mapping. Graphical genotypes and trait values will be compared to narrow down the causal region for each trait.