Construction Of High-Density Genetic Map And QTL Analysis Of Lodging Resistance Based On SLAF-seq Technique In Hulless Barley

Hulless barley?Hordeum vulgare L.var.nudum Hook.f.?is barley without hull,which is also the special crop and the main food grain of the Tibetans and is very important for health and economic development.The need for barley with higher yield and high quality as a functional foodstuff is sharply increasing in recent years with the development of the beer industry and the health food concern of people.Lodging?LD?has become one of the common problems which affects the produceing of higher yield and high quality barley on the Tibetan Plateau.Lodging resistance has become one of the main breeding targets of hulless barley.It is significance utilizing the SLAF-seq technique and QTL analyses to find the key genetic factors and candidate genes of lodging trait in hulless barley.SLAF-seq technology is a simplified genome sequencing technology that can be used to develop and classify high throughput molecular markers?SNP,InDel markers?at one time.Based on the evaluation and the genetic diversity and the population structure of lodging germplasm,the F₂ hybrid population,which crossed by the susceptible cultivar“ZQ320”as female parent and the lodging resistance cultivar“XMLY22”as male parent,was chosen as the experimental materials and large-scale genetic markers exploitation,and was constructed the high-density linkage map of hulless barley,which provided QTL analyses of lodging resistance and yield-related traits.The main results of this study were summarized as following:1.Using 48 SSR markers from 7 chromosomes with better polymorphic bands,a total of 230 allelic bands were identified in 71 hulless barley materials,varying from1 to 10 with the average alleles per SSR locus of 4.79.The polymorphic information content ranged from 0.0547 to 0.8569 with the mean of 0.4898.The variation range of genetics similarity coefficients was 0.469-0.924 with the average of 0.745.Cluster analysis indicated that 71 hulless barley accessions could be divided into Group A,B,C,D and E.These hulless barley materials could be clustered into two subgroups according to population genetic structure analysis.2.According to the analysis of the lodging related traits of 93 germplasm resources of hulless barley?barley?from Tibet,the 45 target traits had a large variation in individual character And it exists a great correlation between the individual characters.Lodging index had positively significant correlated with the length and fresh weight of each internode,but not significantly correlated with the wall thickness of each internode,outer diameter and ratio of wall thickness to diameter,and negatively correlated with wall thickness of third internode and ratio of wall thickness to diameter.The correlation of comprehensive Lodging index with the length of each internode,fresh weight,the wall thickness and ratio of wall thickness to outer diameter is basically same as the lodging index Comprehensive Lodging index was positively significant correlated with bending moment of each internode,lodging index,plant height,height of center and panicle weight,but negatively correlated with bending force and length of panicle.The path analysis showed that the maximum direct path coefficient was the lodging index of the first internode under the panicle,and had a higher positive effect on Comprehensive the lodging index.Cluster analysis indicated that 93 hulless barley germplasm resources were divided into three categories.The second types of lodging index is the largest,followed is the first category,and the third type of lodging index is the smallest.3.The F₂ population with a 92 population size and fine-scale phenotypic separation was screened out as mapping population.SLAF-seq strategy was utilized for genome wide molecular marker development,and the final linkage map with 7linkage groups contained 4,282 markers with an average distance of 0.27 cM between adjacent markers.The number of markers on the linkage group 4 is the largest with1,213 markers and 197.93 cM in length.Linkage group 1 is the shortest which contains 119 markers and 116.16 cM in length.The map was 1,170.54 cM in length with the cover of 77.22%to genome and the average integrity of the SLAF markers in the F₂ mapping population was 90.87%.The markers of partial segregation in the genetic map were filtered out,and the number of markers on linkage map is containing with 992 SLAF markers and 785.53 cM in length.4.Based on the high density genetic linkage map constructed the QTL of 52lodging-related important traits applying were mapped using was 2.05 to 10.83.There are 29 QTLs which can explain the phenotypic variation above 10%,and in which qBFTN3 can explain the rate of contribution of single phenotype of 21.31%,which comes from XMLY22.5.the QTL of 11 yield-related major quantitative traits were mapped by using composite interva1 mapping strategy in the light of the high density genetic map constructed.In total,15 QTLs,which were distributed in 5 linkage groups except LG2 and LG5,were detected The range of phenotypic variance of 5.3%-20.08%was explained.The QTL,which control the number of spikes,was determined at 126.41cM in LG6,and the LOD value was 3.17,which can explain the range of phenotypic variance of 16.94%,and the synergistic gene is from XMLY22.The QTL?qSSW4?,which control the thousand seed weight,was determined in LG4,and the LOD value was 3.01,which can explain the range of phenotypic variance of 9.09%,and the synergistic gene is from ZQ320.