The Major Salt-Relative QTL Located By Molecular Markers In Salt-Tolerance Introgression BC₂ Population Of SR3 With Jinan 177

Current status of agriculture land becomes worse and worse due to man-made and natural changes. Moreover, solid degradation, especially aridity and edaphic salinization, has been a very serious problem in the world for years. Common wheat (Triticum asetivum L.) is one of the most important cereal crops in the world. It is very sensitive to salt-stress which can lead to low productivity of wheat. Therefore, it is very necessary to work on the botanic salt-tolerant mechanisms, to map salt-tolerant genes and to breed new salt-tolerant species by using biotechnology. Years ago, a novel salt-tolerant wheat variety Shanrong No.3 (SR3) generated by using asymmetric somatic hybridization between common wheat Jinan 177 and Agropyron elongatum in our lab, which posses strong tolerance to salt stress. Specifically, one piece of salt-tolerance chromatin from Argopyron elogatum was intrgressed into the Jinan 177 genome, which is salt-tolerent, drought-resistant and high productive. The earlier experiments revealed that the salt-tolerance of SR3 is highly related with the major quantitative trait locus (QTL) located near the centromere of wheat on the long arm of chromosome 5A.In this study, an advanced BC2 population consisted of 171 individuals was constructed from the backcross between SR3 and Jinan 177 after large scale screening under salt stress. For salt-tolerance QTL analysis, microsatellite (SSR), expressed sequence tag-simple sequence repeats (EST-SSR) and BSA (bulked segregant analysis) techniques in combination with the SSR map of wheat were used.221 5A polymorphic markers including 59 SSR primers,26 EST-SSR primers,65 STS primers on wheat chromosome 5A and 31 STS primers on rice chromosome No.9, along with 30 non-5A markers were used to construct a linkage map. Among all of the 211 markers,46 show polymorphism in SR3 and Jinan 177, with a polymorphic index 25.4%. Then PCR amplification has been carried out among the salt tolerance pond and sensitive pond with those 46 marker pairs. A novel molecular marker XBarcl44 was identified. Combined with the SSR high density genetic linkage map (Wheat Ta-SSR-2004-5A) and deletion map (Chinese_Spring_Deletion₅A) of wheat, the major gene for salt tolerance has been located on the 5A long arm of wheat chromosome, the distance to the XBarc144 marker is 12.7 cM, and to the centromere is 5-6cM. Our findings not only narrow the further search scope, laying foundation for mapping salt-tolerance QTL, but also shed light on identification of plant mechanisms for salt tolerance and breeding of new cultivars.