Construction Of High-density Genetic Map And Qtl Analysis Of Fiber-related Traits On Flax

Flax(Linumusitatissimum L.)is an important economic crop with the largest planting area and a long history of culture in China.The main goal of flax breeding is to improve yield,quality and disease resistance.Molecular marker-assisted selection(MAS)can significantly improve the efficiency of breeding and promote breeding process.Molecular marker technology has made some progress in flax germplasm resources classification,system evolution,genetic map construction,resistance gene identification and cloning.However,the avalible SSR markers in flax are still deficient to limited using in breeding projects.In addition,the first step of MAS breeding in flax is to identify the molecular markers related to target traits in the whole flax genome,construct high density genetic linkage map,and identify the traits-related markers.At present,the flax whole genome sequencing has been completed,but the sequence assembly needs to be improved.In view of this,we carried out by the following aspects:1.Reduced-Representation Genome Sequencing was carry out,and 1576 novel SSR markers were developed in flax.Forty eight materials can be divided into two categories by 62 novel SSR markers,one is oil seed flax,and other is fiber flax.2.We established and optimized the flax SSR and SRAP molecular markers technology system,polymorphic primers including 24 pairs of SSR and 32 pairs of SRAP were selected from 100 SSRs and 88 SRAPs,which were used for the construction of the flax genetic linkage map.3.A F2 segregation population was constructed by crossing of the fiber flax cultivar"DIANE" and the oil flax cultivar "Ningya 17",and the primary genetic linkage map with 95 markers was constructed based on 24 SSRs and 71 SRAPs.The linkage map includ 12 linkage groups(LGs)and spanned total length of 546.5 cM.High density genome-wide genetic linkage map was constructed by high-throughput sequencing technology based on the expanding population,which including 2339 SLAF markers were even-distributed in 15 linkage group spanning 1483.25cM of the map distance,and was the highest density genetic linkage map in flax recently.4.Based on the high density genetic linkage map and the flax genome information,we constructed the genome-wide map of chromosome assembly assisted by scaffolds,1321 scaffolds rmounted on the 15 chromosomes,accounted for 11.6%of flax genome assembly information,in which sorting and accurately determine the direction of the scaffolds accounted for 26.27%of the assembly information.5.Combining with the relevant traits phenotypic flax fiber,10 QTLs associated with the traits of plant height,stem length,seed yield,stem yield,fiber yield and fiber content were mapped on high density genetic linkage map,and the above QTLs were located in physical fragments of the flax genome based on flax whole genome assembly information.