Mapping QTL For Salt Tolerant Traits In Wheat Seedling Stage Under Different Salt Stress

Wheat (Triticum asetivum L.) is the largest food crop in the world, which is cultivated in a total area of 200 million hectares. 35%-40% of the world’s population lives mainly on wheat. Wheat is also one of the most important food crops in China. However, the soil salinization seriously hampered its production. Because seedling is the weakest stage of salt tolerance throughout whole life of wheat, it is important to map related gene for the cultivation of salt tolerant wheat varieties.In this study, we reported a new genetic linkage map developed from an F1-derived doubled haploid (DH) population of 168 lines which was generated from the cross between two elite Chinese common wheat varieties Huapei 3 and Yumai 57. SSR molecular markers are used to construct a genetic linkage map. Under different concentrations of salt, the tolerance in seedling stage is identified by measuring the six traits, including seedling height, taproot length, fresh stem weight, fresh root weight, dry stem weight, dry root weight. QTL analyses were performed by using inclusive composite interval mapping based software Icimapping 2.2. The work will provide reference information for gene cloning and molecular marker assisted selection in wheat under salt tolerance. The results are as follows:1. Under four levels of salt treatments, all six salt-tolerant traits, seedling height, taproot length, fresh stem weight, fresh root weight, dry stem weight and dry root weight, have been through correlation analysis. And the results showed that there was a very significant positive correlation between each two traits.2. A total of 324 SSR markers were mapped on 24 linkage groups. Chromosome 5A, 5B and 7B contain two linkage groups. The total coverage of the map is 2485.7 cM, the average genetic distance between marks is 7.67 cM.3. Six wheat seedling traits under different salt treatment using Icimapping 2.2. 61 QTLs were mapped on 16 chromosomes, 1B, 2A, 2D, 3A, 3B, 3D, 4B, 4D, 5A, 5B, 6A, 6B, 6D, 7A, 7B and 7D. 15 of which display larger genetic contribution (over 10%), and could explain 10.33%-36.06% of the phenotypic variation. Different traits located different chromosomes. Traditionally, it is considered major location whose contribution rate is more than 10%. Among them QTLs for seedling height were located on chromosomes 2D, 4B, 5A and 5B; QTLs for taproot length were located on chromosomes 3A, 3D and 7D; QTLs for fresh stem weight 4B and 1B; QTLs for fresh root weight were located on chromosomes 2D and 5B; QTL for dry stem weight was located on chromosome 1B; QTL for dry root weight was located on chromosome 5B.