Genetic Analysis And Mapping Of A Grain Shape Mutant Gene In Triticum Aestivum

Bread wheat (Triticum aestivum) is a globally important crop, accounting for20percent of thecalories consumed by humans. Wheat grain morphology is an important target selection in wheatbreeding history. Wheat grain morphology includes grain size and shape, and they are significantcorrelation with1000-grain weight and milling performance respectively. Therefore, study on wheatgrain size and shape is important for wheat yield and quality genetic improvement.In this study, the wheat dwarf-spherical grain mutant W98identified from Yanzhan1EMS(ethylmethyl sulfide) mutant library was analyzed and the following results were obtained.1. Compared with the wild type YZ1, the mutant has an extreme dwarf phenotype. Therefore, aninvestigation was conducted by accounting the number of the internodes and mearsuring the lengthbetween internodes of wild type and mutant. We found that the dwarf phenotype of mutant W98results from the length of internodes reduced, not from the number of the internodes reduced.2. Sensitivity test of GA and BR indicated that both of wild type and mutant were not sensitive to GA,while the mutant was sensitive to BR and the wild type was not by using the wheat leaf unrollingassay with different BR concentration.3. Genetic analys is was carried out by using F2populations and the derived F2:3progenies gerneratedfrom the cross of W98with Mexico synthetic hexaploid wheat10th12. The mutant parent hasdwarf and spherical grain phenotype, while the other parent has tall stalk and oblong grains. Thetotal population size is1544. Genetic analysis indicated that the spherical grain phenotype iscontrolled by a single incompletely dominant gene. Segregation distortion was detected in thispopulation, perhaps the spherical seed has lower germination rate compared with wild type YZ1.After screen public SSR markers, a genetic map of spherical grain gene was constructed, the genewas mapped onto wheat chromosome1DS. Based on the comparative genomics and draft wheat Dgenome sequence,430new SSR markers were developed. Using these new markers, the distancesof franking markers to target gene were narrowed down to0.4and1.7cM respectively. This resultlays a foundation for further cloning the gene..