Identification Of Genetic Composition And QTL Analysis About The Yield Traits Of The Recombinant Inbred Lines Derived From Trititrigia Germplasm Shannong304 And Yannong15

Thinopyrum intermedium has many excellent traits that wheat does not have,such as large panicles,drought and cold resistance,strong growth potential etc.At present,there are many studies on the excellent disease-resistant and insect-resistant genes of Th.intermedium,but there are few studies on the transfer of yield related beneficial traits from Th.intermedium to common wheat.By backcrossing between Th.intermedium and common wheat Yannong15,our laboratory created the introgressive Trititrigia Germplasm Shannong304,which retained many excellent characters such as large spike,flowery and luxuriant growth of Th.intermedium.By crossing Shannong304 with common wheat Yannong15,we obtained RIL populations with 296 families derived from Trititrigia Germplasm.In this study,296 families of RIL population were identified by molecular cytology,molecular biology and transcriptome analysis.Through the identification of dwarf gene and photoperiod gene in RIL population,based on the evaluation of agronomic traits,the high-quality genetic map of 2D chromosome was reconstructed,and then the QTLs from yield related traits of Th.intermedium were located,and the new germplasm of Th.intermedium with excellent comprehensive traits was screened.The main results are as follows:1.Field investigation and statistical analysis were carried out on 11 important agronomic traits of parents and RIL population.The results showed that agronomic traits of the parent Shannong304 were significantly higher than that of the parent Yannong15,but the heading date was later than that of Yannong15.The analysis of variance and heritability showed that,except the 1000-grain weight was only affected by genotype,other agronomic traits were significantly affected by genotype and environment and had high heritability.2.The fluorescence in situ hybridization(FISH)analysis of 10 long-spike lines and 10short-spike lines in RIL population was carried out using oligonucleotide probe sets.The results showed that the long-spike lines and the short-spike lines had significant differences in the bands of 2A,7A,2B,3B and 6B chromosome.The long-spike material is not only similar to its parent Shannong304 in agronomic characters,but also similar to Shannong304 in chromosome banding structure;However,the short-spike material is more similar to its parent Yannong15 in agronomic traits and chromosome banding structure.3.According to the detection results of molecular markers,the genetic difference map of 18 chromosomes in RIL population was constructed.The map can distinguish different types of genetic differences and the source of chromosome fragments.We found that the different lines of RIL population were rich,and some results were consistent with cytology.4.QTL mapping was carried out for 11 important agronomic traits of parents and RIL population.A total of 30 correlated QTL were detected,explaining 2.5%-23.3% of phenotypic variation,and the LOD value was between 2.53-18.84.All QTL have been detected in the environment of previous years and are stable QTL.5.The specific molecular markers of dwarfing gene and photoperiod gene were used to detect 296 materials from RIL population.The results showed that among 296 materials tested,156 materials including Yannong15 contained the dwarf gene Rht8 and an average plant height of 69 cm,while 141 materials including Shannong304 contained rht8 gene,with an average plant height of 76 cm;193 materials including Yannong15 contained the photoperiod-insensitive gene Ppd-D1 a and an average heading period of 176 days.91 materials including Shannong304 contained the photoperiod-sensitive gene Ppd-D1 b and an average heading period of 182 days.The results showed that the two genes had independent and cumulative effects,and the effects of both Ppd-D1 a and Rht8 genes on plant height and heading date were greater than those of only one of them.6.Based on the QTL analysis of the cause/result conditions of all 296 RIL families,the relationship between plant height and ear length,plant height and heading date at a single QTL level was revealed.The results of conditional QTL analysis showed that QPh-R-2D(including Rht8 gene)could be located in both conditional and non-conditional QTL,and the LOD value changed little,indicating that the genetic effect of this QTL was not affected by the ear length or heading date conditions,and it was a QTL with important contribution to plant height.7.Based on the difference of spike length between Shannong304 and Yannong15,the transcriptome analysis was performed on the young ears of the representative large and small spike families R104 and R223 in the two ridge and tetrad stages.There were 145 differentially expressed genes about spike difference in the two stages.Among them,Traes CS2B02G005300、Traes CS2D02G523000 and Traes CS2D02G597600 are involved in the process of plant growth and differentiation at both stages,and are almost not expressed in Yannong15,but only specifically expressed in Shannong304.These genes may be candidate genes related to spike length development.