The Major Salt-Relative QTL Located By Molecular Marker SSR And EST-SSR In F2 Population Of SR3 With Jinan 17

Solid degradation, especially aridity and edaphic salinization, has been a very serious problem around the world. Common wheat(Triticum asetivum L.),one of the most important cereals, is very sensitive to salt-stress.Therefore, it is important to breed new salt-tolerance wheat cultivars by biotechnological methodologies. This urges us to elucidate the botanic salt-tolerant mechanisms as well as to map and clone salt-tolerant genes based on molecular marker technologies.Because of its hexaploidy and huge genome, the application of molecular marker technologies in wheat is behind other crops, e.g. barley, maize and rice. Recently, however, such application in the salt-tolerance of wheat has been largely accelerated following the development of the molecular marker numbers and technologies examination systems.A novel salt-tolerant, drought-resistant and high productive wheat variety Shanrong No.3(SR3)was generated via asymmetric somatic hybridization between common wheat Jinan 177 and Agropyron elongatum in our lab.Specifically, several pieces of chromatins from Argopyron elogatum were intrgressed into the Jinan 177 genome, which may offer the excellent traits of SR3.In our early research, salt-tolerance of the F2 population originating from a cross between SR3 and Jinan17, a salt-sensitive wheat cultivar, were determined by microsatellite(SSR) and BSA (bulked segregant analysis) techniques in combination with the SSR map of wheat.It has primarily presented that salt-tolerance of SR3 is likely controlled by a major QTL which locates on chromosome 5AL between markers xgwm304 and xgwm666.In this work, in order to gain a higher resolution mapping of the major QTL governing SR3's salt-tolerance, F2 population with 340 lines of SR3 and Jinan 17 was re-constructed.Besides, we improved the BSA techniques with molecular marker assisted selection. Genetic and SSR, EST-SSR, STS analysis were performed among individuals in F2 segregated population, using 59 SSR marker pairs,83 EST-SSR marker pairs and 31 rice SSR marker pairs. Among all of these marker pairs,27 showed polymorphism, with a lymorpolymorphic index of 15%.Then PCR amplification was carried out among the salt-tolerant pond and salt-sensitive pond with these marker pairs.Of them, Xcfa2141,WMS410, xgwm304, xgwm666, BE-5 and TC245679 showed coherence to the parents.Comparing with the high density genetic linkage map published, the major-QTL was located on the position of 5AL12-0.35-0.57 with the same similar rank and the genetic distances calculated by software Mapmaker 3.0.Based on this result, we searched all EST sequences in this interval and designed 96 STS primers. By the same PCR amplification, we found some polymorphic marker pairs which are related with salt-tolerance. Then EST sequences amplified with these polymorphic marker pairs were analyzed, and some of them were found to be salt-tolerance candidate genes for further study. Summarily, this work provides a solid foundation for the next map-basic cloning.