Mapping and gene cloning of a wheat mutant with dwarf and compacted spikes.

Plant height and spikelet density are two important traits for wheat ( L.) yield. The development of wheat mutants not only provides new genetic resources for wheat improvement but also facilitates our understanding of the molecular regulation of these traits. Previously, we obtained a mutant named dwarf and spike compactness () from wheat cultivar Guomai301 (wild type, WT) treated with ethyl methane sulphonate. This study investigates the heredity, mutated gene location, and the candidate gene of . Highresolution chromosome painting analysis indicated that there were no visible structural variations in the mutant . Genetic analysis indicated that the phenotype of dsc was controlled by a single dominant gene, named as . The wheat 660 K single-nucleotide polymorphism (SNP) array and simple sequence repeat (SSR) marker assay were employed to map the mutated gene. A total of 984 SNPs were identified between the DNA bulks, among which, 492 SNPs were located on chromosome 5A in 580-680 Mb genomic region, which occupied 50% of the total SNPs. The gene was mapped in a 33.4 Mb (625.7-659.1 Mb) region on chromosome arm 5AL, flanked by SSR markers and , where is located. Sequences and expression patterns of from WTand dsc were compared. The two s had a SNP (G>A) in the binding site. A dCAPS marker was developed based on the SNP, and the marker was cosegregated with the mutated phenotypes in a F population derived from the cross x Chinese Spring (CS). This result demonstrated that the gene was the mutated gene of . The expression levels of were significantly higher in roots, stems, leaves and spikes of mutant than those in WT. Our results demonstrated that point mutation in the binding site of the likely increased its transcript level via a reduction in miRNA-dependent degradation, and this resulted in pleiotropic effects on spikelet density and plant height. Obviously, - was a key regulation module for wheat growth and spike development. The dCAPS marker could be used to detect the elite allele of in wheat breeding. Regulation of - module might be an approach for wheat yield breeding.