Genetic control of sugar-auxin crosstalk that determines yield potential in barley

Spikelet development is an inherited complex trait influenced by several endogenous, genetic, and environmental factors. This study aims to find the genetic factors controlling the maximum yield potential (MYP) in a core set of 250 diverse spring barley accessions. To achieve this, we evaluated a collection of 250 barley spikes at three different developmental stages MYP, green anther (GA), and awn tipping (TIP). We also, measured the sugar (sucrose, glucose, and fructose) contents from each accession of the collection. Six-rowed accessions showed higher phenotypic variation for all studied traits than two-rowed. The spikelet-related traits showed a highly significant positive relationship with the sugar contents. Based on a genome-wide association study (GWAS) outputs, four quantitative trait nucleotide regions (QNRs) containing 37 significant quantitative trait nucleotides (QTNs) were identified, which encompass plausible candidate genes. The highest significant QTNs on 1H were located inside the HORVU.MOREX.r2.1HG0042180 and HORVU.MOREX.r2.1HG0072210 that encodes sugar transporter and auxin response factor. These candidate genes potentially promote sucrose accumulation and auxin during spikelet development by regulating sugar hydrolysis and transport in addition to auxin biosynthesis. Differential expression profiling revealed that these candidate genes are also highly expressed during spike development, confirming their potential role in regulating spikelet survival.