Construction Of Genetic Maps And QTL Mapping For Resistance To Soil-borne Mosaic In Wheat

Wheat, one of the three most important cereals for human, is the most widely planted staple crop in the world. Traditional wheat breeding method, needing multiple generations of selection and relying on the experience of breeders, is time-consuming and laborious. Molecular technology and genetic maps are effective tools, which can facilitate understanding and manipulate of genes controlling complex traits. Assisted by linkage markers, chromosome regions with interesting gene/QTL can be assembled together to be interesting genotypes. Breeding new cultivars or improving certain trait in short period become possible. Soil-borne Wheat Mosaic (SBWM) was firstly discovered in the USA in1919, and has been reported in many countries, such as Argentina, Brazil, China, Egypt, France, Italy, and Japan. SBWM is one of the few diseases of winter wheat that can practically destroy an entire crop of a susceptible cultivar. Developing resistant gene or germplasm, breeding and planting SBWM resistant or tolerant cultivars is an effective and environment friendly method to control SBWM disease. Up to now, study taken in soft red wheat cultivar or germplasm is still limited. In this study, two soft red wheat cultivars with resistance to SBWM, Pioneer26R61and AGS2020, were detected for SBWM resistance QTL. Their linkage markers were validated for potential use in MAS for the major QTL. The main results were following:(1) A whole genome map of Pioneer26R61/AGS2000population was constructed using DArT and traditional SSR markers, then enriched using SNP markers. The final map has2734loci, with a total length of2135.7cM for all21chromosomes, and average interval length of0.79cM. There were471DArT and SSR markers, without mapping information before, firstly assigned to specific chromosoms in this map. This map was used in whole genome QTL mapping for SBWM resistance. Another map from Chuan35050/Shannong483population was also enriched in this study to facilitate the nutrition use efficiency study in our lab; the enriched map had338more markers than the original map and the average interval length was shortened from14.8cM to7.15cM. For AGS2020/LA95135population, the genetic map of chromosome5D was constructed, with19loci and covering207.8cM genetic distance, and used to detect SBWM resistance QTL in AGS2020.(2) In Pioneer26R61/AGS2000and AGS2020/LA95135population, the same major QTL, QSbm.uga-5DL, was identified in all environments with highly significant LOD values, explaining up to62%and65%of the total phenotypic variation, respectively. The QTL was closely linked to markers Xbarc161and Xbarc177. There were also4minor QTL detected in Pioneer26R61/AGS2000population, located on chromosome arm1BL,2BS,3BL,5A and5BL(3) Out of147lines and cultivars,142materials with the same performance to SBWM in the field test as predicted by linkage markers Xbarc161and Xbarc177, validated the potential use in marker assisted selection of the two markers.(4) Using the linkage markers Xbarc161and Xbarc177, we selected or predicted112advanced lines (cultivars) possibly with SBWM resistance out of123materials in UGA breeding program. In177Chinese cultivars or lines of Huanghuai winter wheat region,8materials have Xbarc161and Xbarc177resistant band and may have the SBWM resistance.