Construction Of Intraspecific Genetic Linkage Map And Qtl Analysis Of Phytological Traits And Phytophthora Tapsici Resistance In Pepper (Capsicum L.)

Pepper（Capsicum annuum L.）, one species of family Solanaceae,genus Capsicum is cultivitedwordwide because of its high nutritional value and good environmental adaptability.In this study,based on two recombinant inbred lines populations,, and a genetic map with SSR,CAPS, SNPS and other molecular markers,QTLs analysing the phytological traits of the twopopulations and disease resistance of one population was performed,, Tightly linked markers correlatedwith these characters were expeted to develope for marker-assisted selection (MAS) in pepperbreeding.High-density genetic map is the basis of genetic research, therefore, SNP markers were developedin this study based on the simplified genome sequencing technology (SLEF-sequence) to construct ahigh-density genetic map.That would improve the accuracy of pepper QTL analysis and help for furtherfine mapping and cloning of genes.The main contents and results in our study are as follows：（1）The investigation and analysis for phytological traits and resistance against Phytophthoracapsici: The phytological traits of RILs(83-58×perennial) intraspecific population and RILS(H3×83-60)intraspecific population and these four parents were investigated in different years, following the IPGRIas reference.Resistance to Phytophthora capsici of RILs(83-58×perennial) population was identified.The Phytophthora capsici was inoculated on bifurcation phase of the plants, using the stem cuttinginoculation method.The resistance was evaluated in three index:Recepbility、 Inducibility andStability.The results showed that, the distribution of these investigated datas were skewed normal andthe distribution of bar charts is continuous distribution, survey data were jointly influenced by multiplegenes and the environment, all the above suggest that these traits were influenced by environmentsCorrelation analysis results showed that,two populations of investigation traits, First Flower Node wassignificantly positively related with Plant Height、Leaf Length and Leaf Width, Fruit Diameter wassignificantly positively related with Fruit Shape Index.（2）Polymorphic marker selection and linkage map construction of group RILs(83-58×perennial)：RILs(83-58×perennial) mapping population was derived from an intraspecific(C. annuum) cross ofinbred line83-58and perennial,122lines were selected randomly for linkage map construction. With aLOD threshold of2.5, an intraspecific linkage map composed of18linkage groups were constructed,composed of105SSR,23CAPS markers,1SCAR markers and two morphological markers (C andup).This map covers a length of633.71cM. The average distance between two markers was4.8cM inthis linkage map.（3）QTL analysis of phytological traits and resistance against Phytophthora capsici ofRILs(83-58×perennial) population: phytological traits of RILs(83-58×perennial) population andresistance against Phytophthora capsici were analyzed by software QTLIcimaping2.0.As a result,a totalof21QTLs were revealed for10phytological traits(First Flower Node、Stem Length、Plant Elongation、Lateral Bud、 Fruit Shape Index、Fruit Shape、Number of Ventricle and Fruite Width) and resistance against Phytophthora capsici. There are14QTLs that have a more explanation amount of phenotypicvariation than10%,60.8%of the total number, and there are three QTLs can be revealed repeatly in thetwo investigation.The LOD values of these QTLs range from2.7to19.1, explanation amount ofphenotypic variation range in7.2%~81.4%.（4）Linkage map construction of group RILS(H3×83-60)： The study constructed a high-densitylinkage map RILS(H3×83-60) by the a simplified genome sequcing method–SLEF-seq (speceficlength amplified fragment sequencing).The high-density linkage map RILS(H3×83-60) is composed of7,331molecular markers of12linkage groups,incluing7,308SNP markers and22SSR markers. Thismap covers a length of1973cM,which was the most saturated linkage map in the world.The averagedistance between two markers was0.27cM in this linkage map and the average length of these12groups was164.4cM.（5）QTL analysis of phytological traits of RILS(H3×83-60) population: phytological traits ofRILS(H3×83-60) population were analyzed by software MapQTL4. Under a LOD threshold of3.0,using the method of IM(interval mapping)and CIM(composite interval mapping), a total of35QTLswere revealed for11phytological traits(First Flower Node、Stem Length、 Leaf Length、 Leaf Width、Leaf Area、Petiole Long、Fruit Areola、Fruit Neak、Fruit Shape、Number of Ventricle、Fruite WallThickness).The distribution of these QTLs were uneven, located on the remaining10chromosomesexcept chromosome6,9.Some QTLs showed coincidence and linkage.Among them, First Flower Nodeand Petiole Long are controled by the the most QTLs.（6）Conjoint analysis for the QTLresults of the two groups: a total of six traits had QTLlocationsin these two groups,which included First Flower Node、Plant Height、Leaf Length and Leaf Width、Number of Ventricle、Fruit Shape Index,and First Flower Node、Leaf Length、Number of Ventricle、Fruit Shape Index had same QTL located on same chromosome,but it can not be ture that these twoQTL were the same site.Coincidence and linkage phenomenons were found in these QTL results of thetwo groups, which were consistent with the correlation analysis of survey data.