Kernel weight (KW), together with kernel number per unit area, determines yield of cereal crops. Here, two barley recombinant inbred lines (RILs) populations with a shared parent were used to identify loci controlling KW. One is Baudin/AWCS276 (BA) for which a linkage map was available. Several large-effect QTL controlling KW were detected in this population. Another is Morex/AWCS276 (MA). A linkage map with 5273 makers formed 1454 clusters, was constructed by the genotyping by sequence (GBS) data of 201 RILs from this population. A single marker was selected to represent each of the clusters and the linkage map constructed with these markers covers a total length of 1022.4 cM with an average interval of approximately 0.7 cM between loci. Three of the large-effect loci controlling KW (located on 2HL, 6HL, and 7HL, respectively) identified from the BA population were also detected in the MA population under different environments. The locus on 6HL was detected in each of the experiments conducted for both populations thus was selected for developing near isogenic lines (NILs). Apart from KW, the two isolines for each pair of the putative NILs obtained showed no significant difference for any of the morphological characteristics assessed. The average difference in KW between the isolines for all the NILs obtained was about 15% based on assessments under both glasshouse and field conditions. Taken advantage that high quality genome assemblies for both Morex and AWCS276 are available, we identified candidate genes underlying two of the three loci based on an orthologous analysis. The NILs developed and the candidate genes identified in this study should facilitate the cloning and functional analysis of genes regulating KW in barley.

Fusarium crown rot (FCR), a chronic and severe disease caused by various Fusarium species, is prevalent in semi-arid cropping regions worldwide. One of the major QTL conferring FCR resistance was detected on chromosome arm 1HL (Qcrs.cpi-1H) in barley. To develop markers that can be reliably used to incorporate the resistance locus into breeding programs, we developed and assessed a near-isogenic line-derived population consisting of 1180 recombinant inbred lines targeting the locus. Using this population, we delineated Qcrs.cpi-1H into an interval of 0.4 cM covering a physical length of about 487 kb. Six markers co-segregating with this locus were generated. Co-linearity for genes located in this interval between the genome of barley and those of either rice or Brachypodium distachyon is poor. Three genes with non-synonymous variations between the resistant and susceptible lines were identified within the interval. The results reported in this study not only provide markers for integrating Qcrs.cpi-1H into breeding programs, but also form a solid foundation for cloning the causal gene(s) underlying this locus.