AbstractKey messageAnalyses of barleymat-closs of function mutants reveal deletions, splice-site mutations and nonsynonymous substitutions in a key gene regulating early flowering.AbstractOptimal timing of flowering is critical for reproductive success and crop yield improvement. Several major quantitative trait loci for flowering time variation have been identified in barley. In the present study, we analyzed two near-isogenic lines, BW507 and BW508, which were reported to carry two independent early-flowering mutant loci,mat-b.7andmat-c.19, respectively. Both introgression segments are co-localized in the pericentromeric region of chromosome 2H. We mapped the mutation in BW507 to a 31 Mbp interval on chromosome 2HL and concluded that BW507 has a deletion ofMat-c, which is an ortholog ofAntirrhinum majus CENTRORADIALIS(AmCEN) andArabidopsis thaliana TERMINAL FLOWER1(AtTFL1). Contrary to previous reports, our data showed that both BW507 and BW508 areMat-cdeficient and none of them aremat-b.7derived. This work complements previous studies by identifying the uncharacterizedmat-c.19mutant and seven additionalmat-cmutants. Moreover, we explored the X-ray structure of AtTFL1 for prediction of the functional effects of nonsynonymous substitutions caused by mutations inMat-c.