Identification of barley genetic regions influencing plant–microbe interactions and carbon cycling in soil

Purpose Rhizodeposition shapes soil microbial communities that perform important processes such as soil C mineralization, but we have limited understanding of the plant genetic regions influencing soil microbes. Here, barley chromosome regions affecting soil microbial biomass-C (MBC), dissolved organic-C (DOC) and root biomass were characterised. Methods A quantitative trait loci analysis approach was applied to identify barley chromosome regions affecting soil MBC, soil DOC and root biomass. This was done using barley Recombinant Chromosome Substitution Lines (RCSLs) developed with a wild accession (Caesarea 26-24) as a donor parent and an elite cultivar (Harrington) as recipient parent. Results Significant differences in root-derived MBC and DOC and root biomass among these RCSLs were observed. Analysis of variance using single nucleotide polymorphisms genotype classes revealed 16 chromosome regions influencing root-derived MBC and DOC. Of these chromosome regions, five on chromosomes 2H, 3H and 7H were highly significant and two on chromosome 3H influenced both root-derived MBC and DOC. Potential candidate genes influencing root-derived MBC and DOC concentrations in soil were identified. Conclusion The present findings provide new insights into the barley genetic influence on soil microbial communities. Further work to verify these barley chromosome regions and candidate genes could promote marker assisted selection and breeding of barley varieties that are able to more effectively shape soil microbes and soil processes via rhizodeposition, supporting sustainable crop production systems.

Analysis and mapping quantitative trait loci for histidine content in barley (Hordeum vulgare L.) using microsatellite markers

Mining the gene of histidine content in barley grain helps with the breeding of functional barley varieties. The study constructed a recombinant inbred lines (RILs) containing 193 families derived from the cross between Ziguangmangluoerling (ZGMLEL) (♀) and Schooner No.3 (♂). The histidine (HIS) content in the grain of the mapping population and its parents were determined by an automatic amino acid analyzer. The HIS content of ZGMLEL was 0.53 mg/g. The grain HIS content of Schooner No. 3 was 0.21 mg/g, and the grain HIS content of population ranged from 0.23 to 0.54. Genetic linkage maps, including those of seven chromosomes of barley, were constructed by using 180 pairs of simple sequence repeat (SSR) markers, with a total genetic distance of 2671.03 cM and average marker spacing of 14.84 cM. Quantitative trait locus (QTL) IciMappingV3.3 was used to analyze QTL of HIS content in barley grains, and three QTLs were detected. Mapping results showed that the three loci were located on chromosomes 2H, 4H, and 7H, respectively. The major QTL with a contribution rate of 10.11% was located on barley chromosome 4H (HVBAMMGB84-BMAG0808). The additive effect is positive (0.025). Thus, it comes from the high-value parent ZGMLEL. Another major QTL with a contribution rate of 13.75% was located on barley chromosome 7H (GBM1303-GMS056). The minor QTL with a contribution rate of 6.01% was located on chromosome 2H (Scssr03381-Scssr07759). The additive effects of 4H and 7H QTLs were negative (− 0.02 and − 0.033). So, they came from the male parent Schooner. The results provided a reference for further fine mapping, cloning, and transformation of HIS genes in barley grains.