genes controlling barley malt quality: a qtl meta-analysis

Objective: malt quality in barley is a complex quantitative trait governed by multiple genes and influenced by environmental factors, making genetic improvement challenging. the present study aimed to integrate qtl data from multiple independent studies via meta-analysis to identify stable, consensus genomic regions (mqtls) that control key malt quality traits. the ultimate goal was to provide reliable genomic targets for marker-assisted selection to accelerate breeding programs for improved barley malt quality.methods: a comprehensive literature search was conducted across web of science, scopus, pubmed, sciencedirect, and google scholar to identify all published qtl studies related to barley malt quality. a high-density consensus genetic map was constructed by integrating several well-established reference maps. the unified map incorporated multiple marker systems, including aflp, ssr, rflp, rapd, sap, dart, est, caps, sts, rga, iflp, and snp markers, ensuring comprehensive genome coverage. individual qtls were projected onto the consensus map, and the optimal number of mqtls per chromosome was determined using the akaike information criterion, bayesian information criterion (bic), and empirical bayesian procedures. to validate the biological relevance of the identified mqtls, genes located within 2 mb intervals flanking each mqtl peak position were retrieved from major genomic databases, including ensemblplants, graingenes, ncbi gene, and barleymap.results: through meta-analysis, the 184 individual qtls were consolidated into 35 mqtls distributed across all seven barley chromosomes. the most significant mqtl, designated mqtl7.2, harbored 25 overlapping qtls and explained 68% of the phenotypic variance. mqtl6.4 contained 12 qtls controlling alpha amylase, diastatic power, viscosity, beta glucan, wort beta glucan, and grain protein content, explaining 38% of phenotypic variance. gene mining within mqtl intervals identified 54 unique candidate genes. gene ontology enrichment analysis revealed significant involvement in monoatomic anion transport, tetracycline transmembrane transport, mrna pseudouridine synthesis, and transmembrane transporter activity. microrna prediction revealed 33 unique mirnas regulating the identified genes, with hvu mir6192, hvu mir6184, hvu mir6182, hvu mir6176, hvu mir6189, and hvu mir6214 targeting multiple genes. conclusion: the identified mqtls exhibited substantially narrowed confidence intervals compared to individual qtls, providing more precise genomic targets for breeding applications. eleven major mqtls with r² values exceeding 20% represented high-priority genomic regions for marker-assisted selection. the mega mqtl7.2, explaining 68% of phenotypic variance and harboring qtls for multiple malt quality parameters, represents a particularly valuable breeding target. these findings will facilitate marker-assisted selection strategies to accelerate genetic improvement of barley for the malting and brewing industries, ultimately contributing to the development of superior malting barley cultivars with enhanced quality characteristics.