Screening And Identification Of Wheat Germplasm For Salt Tolerance And Mapping QTL For Salt Tolerance Traits Using Artificial Sea Water

Salinity is a major limitation to crop production in coastal region. Breeding for salinity tolerance could be an effective way of improving yield and yield stability on saline-alkaline soils. However, these require a good understanding of the inheritance of this trait and occupy massive amounts of elite genetics resources tolerant to salt-stress. To provide information of salt tolerance in wheat breeding in coastal areas, different concentrations of artificial sea water and salt-tolerant indices were applied and two wheat accessions with high salt-tolerant were screened in this study. A recombinant inbred line (RIL) population of 91 lines which was generated from the cross between Lang and 22397 were evaluated for QTL mapping related to salt tolerance.1. To select the salinity concentration suitable for identifying the salt tolerance of wheat at the germination and seedling stage, different concentrations of artificial sea water and salt-tolerant indices were applied in this study. The results showed that two methods were available to evaluate wheat salt tolerance by comparing the mean value of specific evaluation indices calculated by using the method of fuzzy membership function. One was used for measuring wheat salt-tolerance at the germination stage by calculating the mean value of the relative germination percentage on 65% sea water stress and the relative shoot length on 40% sea water stress. And the other was suitable for identifying wheat salt-tolerance at the seedling stage by using the joint mean value of the relative value of shoot growth, root growth, dry weight of overground part and dry weight of underground part on the 40% sea water stress. The salt-tolerance of 16 varieties were identified clearly at the two stages by the two methods. Based on the fuzzy membership function theory, the methods of comparing the joint mean value of specific evaluation indices can be used to assess wheat salt tolerance at the germinating and seedling stage.2.363 accessions were evaluated for salt tolerance at the germination stage using artificial sea water. Among accessions tested,28 wheat cultivars with salt tolerance grade 1 were identified. To obtain further salt-tolerant accession at the seedling stage,48 wheat accessions were selected from the salt tolerance resources (grade 1 or grade 2) at the germination stage to evaluate salt-tolerant at the seedling stage. Two wheat accessions with high salt-tolerant were screened by using the methods of fuzzy membership function. They were Huaimai 31 and Hongkeyangmai, respectively. Based on the original of the wheat germplasm, the capacity of salinity tolerance was different:local varieties>improved varieties>introduced varieties. Correlation analysis of wheat salt tolerance at the germination stage and the seedling stage showed that there is no consistent correlation existed.3. A recombinant inbred line (RIL) population of 91 lines which was generated from the cross between Lang and 22397 were evaluated for salt tolerance using artificial sea water. Nine traits including germination rate, germinating energy, germination index, shoot length, root length, fresh weight of overground part, fresh weight of underground part, dry weight of overground part and dry weight of underground part of 91 lines were evaluated for salt tolerance.16 QTLs related to Eight traits including germination rate, germinating energy, germination index, shoot length, root length, fresh weight of overground part, fresh weight of underground part and dry weight of underground part were mapped on chromosomes 7B,1 A,2A,4B,7D,5B,7A, and ID.5 QTLs contains wPt-6268～wPt-4771, wPt-6709～wPt-7746, wPt-6872～wPt-0745, wPt-1302～wPt-1261 and wPt-9664～wPt-3707 can be simultaneously mapped on both traits. QTLs related to salt tolerance traits in germinating stage mainly mapped on chromosome 7B,1A and 2A, which accounted for 11.90%-32.11%of phenotypic variance, wPt-6709-wPt-7746 on chromosomes 1A accounted for 32.11% of phenotypic variance, which is the highest in germinating stage. QTLs related to salt tolerance traits in seedling stage mainly mapped on chromosome 4B, 7D,5B,7A and 1D, which accounted for 10.55%～18.92% of phenotypic variance, wPt-5564-wPt-4766 on chromosomes 4B accounted for 18.92% of phenotypic variance, which is the highest in seedling stage.