The Genetic Analysis For Important Agronomic Traits From Wild Barley And Construction Of CeRNA Regulatory Networks

Barley is the fourth largest cereal crop in the world after maize,rice and wheat,and also is one of the earliest domesticated crops.Wild barley is the progenitor of cultivated barley,and over the course of crop domestication and improvement,many important agronomic traits of cultivated barley have been improved,but the diversity of cultivated barley has also been eroded by forces.Clearly,wild barley has rich genetic and phenotypic diversity.It is an effective way to broaden the genetic basis of cultivated barley by mining the genetic resources of controlling important agronomic traits in wild barley and using them in cultivated barley breeding.In the study reported here,the agronomic traits were measured between the wild barley and cultivated barley to discover the significant differences and important agronomic traits.Recombinant inbred line(RILs)populations were constructed to detecte loci controlling the important agronomic traits in multiple environments.The marjor QTL from wild barley were further used to predict candidate genes and construct competing endogenous RNA networks.Main results obtained from the study include:1.A Middle East wild barley AWCS276 was used to compare the 13 important agronomic traits with two cultivated barleys(Morex and Baudin)in many years,like tiller number,tillering angle,spike exsertion length,spike length,kernel number per spike,flag leaf length,flag leaf width,the ratio of flag leaf length and width,flag leaf area,kernel length,kernel width,the ratio of kernel length and width,and hundred kernel weight.Statistical analysis found that significant or extremely significant difference in 13 agronomic traits between wild barley AWCS276 and other two cultivated barleys was detected under different environments.Two RILs(Morex/AWCS276(MA)and Baudin/AWCS276(BA)were generated from cross between wild barley AWCS276 and two cultivated barley respectively.In each population,those agronomic traits all show the advantage of being super-parent.These results indicate that the genetic backgrounds of wild barley and cultivated barley are quite different,and their hybrid progeny are suitable for genetic analysis.The genetic recombination of wild barley and cultivated barley can provide more genetic fundation for breeding high-yielding cultivars.2.To detect candidate genes that control important agronomic traits from wild barley,MA and BA RILs populations were sequenced to constructe genetic linkage maps.The genetic linkage map of MA RILs population covers a total length of 1022.4 c M containing1454 SNPmakers,and genetic linkage map of BA RILs population was 927.37 c M long,and contained 1832 DAr T markers.99.2% and 87% of the genetic markers in the MA and BA population respectively were consistent with the Morex physical map sequence.3.In both MA and BA populations,36 QTLs were identified from wild barley respectively,distributing on 7 chromosomes,contributed between 6.7 and 68.1% of the phenotypic variance among the experiments,and LOD scores varied from 3 to 32.3.Among QTL with effects derived from wild barley,10 major QTLs can be stably identified in two RILs populations,controlling the tillers number(TN-5H)and flag leaf width(FLW-6H),flag leaf area(FLA-6H),the ratio of flag leaf length and width(FLR-2H),kernel length(KL-4H),kernel width(KW-6H),the ratio of kernel length and width(KR-4H)and hundred kernel weight(HKW-2H,HKW-6H,HKW-7H).Among them,HKW-6H was detected in each of the experiments conducted for both populations,explaining up to 19.7% of the phenotypic variation.So HKW-6H is the major gene controlling hundred kernel weight,thus was selected for developing near isogenic lines(NILs).Apart from hundred kernel weight,the two isolines for each pair of the putative NILs obtained showed no significant difference for any of the morphological characteristics assessed.The difference in hundred kernel weight between the isolines for all the NILs obtained was from 0.38 g to 1.05 g based on assessments under both glasshouse and field conditions.4.Taken advantage that high quality genome assemblies for both Morex and AWCS276 are available,we identified 58 candidate genes underlying10 major QTL based on an orthologous analysis,14 of which have multiple amino acid differences between the parent lines.These major QTLs and candidate genes from wild barley can be used for developing molecular markers,and accelerateing the process of breeding.5.The 10 major QTL from wild barley mainly controlled the agronomic traits related to tiller,grain and flag leaf.Gene regulatory networks were constructed in barley for the 58 candidate genes of 10 major QTL.186 mi RNAs and 1491 m RNAs were indentified in regulating barley tillers,grains and flag leaves,and 59 mi RNAs were differentially expressed and regulated 749 target genes.Combining candidate genes of 10 major QTL,mi RNAs,and lnc RNAs identified in the laboratory,we constructed 39 competitive endogenous RNA regulatory networks,and four regulatory networks contained eight major QTLs with six candidate genes.It indicated that non-coding RNA and coding RNA could work together to regulate the growth and development of barley.These results are conducive to the subsequent functional research of the cabdidate genes of wild barley.