Construction Of Genetic Map And Genetic And QTL Analyses For Daily Flowering Time In Iris Domestica ×I.Dichotoma

Both Iris domestica and I.dichotoma are perennial herbaceous plants in Iris（Iridaceae）.The flowering period of both of them was from June to August,the single flowering period was one day,and the total amount of flowers was large and the flowering period was long.The opening time of I.domestica is at 6:30 in the morning,and the opening time of I.dichotoma is at 15:00 in the afternoon.The flowering period of the two can meet,They can produce fertile hybrid offspring,making them good materials for studying the opening and closing times of flowers in a single day.In this study,because I.domestica has the characteristic of early opening time,we selected I.dichotoma and I.domestica as parents to cross,and then created F₁,F₁selfed created F₂population.We combine with RAD sequence and SNP molecular marker technology,then construct a genetic map of I.dichotoma and I.domestica,By measuring the daily flowering time and closing time of I.dichotoma,I.domestica and their F₁and F₂generations,the opening time was divided into 5 states（S1-S5）and the closing time into 4 states（S6-S9）,and then the mixed genetic analysis of major genes and polygenes and QTL analysis were conducted.The aim of this study was to clarify the inheritance of F₂generation of I.dichotoma×I.domestica,and provide theoretical basis for the isolation and cloning of opening time genes and molecular marker assisted selection breeding in the future.The main conclusions are as follows:（1）The daily flowering time and closing time traits of I.dichotoma,I.domestica and their F₁and F₂generations were investigated.The results showed that the coefficient of variation of opening time and closing time of parents and F₁generations were less than 2%,and F₂generations had rich variations,the coefficient of variation of opening time was 12%-18%,and the coefficient of variation of closing time was 5%-8%.Moreover,the opening time and closing time in F₂generation plants belong to the continuous distribution of multi-peak or single-peak,which conformed to the characteristics of quantitative traits,and the opening and closing time traits of some plants have transgressive segregation.（2）The major gene+polygene genetic model was used for analysis,the genetic models of 9 states of opening time and closing time investigated on different dates were obtained,including two pairs of major gene models（B model）,two pairs of major gene+polygene models（E model）and polygene models（C model）.Flower opening time is mainly controlled by two major genes,and some traits are also modified by polygenes.The heritability of major genes is 65.14%-98.47%,the heritability of polygenes is 0.41%-34.39%,and the environmental variation was 0.13%-3.50%.Only the S4 stage investigated on July 31^stwas different from the other stages of opening time.Although the E-4 model was consistent,the polygenic heritability was 97.99%.The closure time of flowers is mainly controlled by two pairs of major genes,and some traits are also modified by polygenes.The major gene heritability was 61.07%-97.05%and the polygenes heritability was 3.56%-38.15%,the environmental variation was 0.1%-3.14%.However,the results of S6（C-0）on July 18^thand19^thand S8（E-5）on August 22^ndshowed that both were mainly controlled by polygenes.（3）Randomly selected 150 plants from F₂hybrids for mapping,RAD-seq technology was used to obtain 524.11G data,with an average of 18.53G data for each parent sample and3.37G data for each progeny sample.The GC base in Clean Data accounted for 46.59%of all bases,and the sequencing Q30 was 95.55%,the average sequencing depth of parents was6.13×,and the average sequencing depth of offspring was 4.65×,and 26427 polymorphic loci were obtained by bioinformatics analysis.Crosslink software was used to construct the first genetic linkage map of I.dichotoma×I.domestica,including 26 linkage groups,total map distance 3237.39 c M,average map distance 2.46 c M,total map marker 1315,among them,after removing the same marker,the male map contains 1274 markers,the female map contains 1268 markers,and the neutral map contains 1293 markers.（4）QTL loci for opening time and closure time were mapped by R/qtl software based on genetic linkage map and opening time data.A total of 22 loci were detected to be associated with opening time and closure time traits.In the open time traits,7 loci were detected to be associated with S1 traits,which were located in linkage groups 3,4,15,16 and 24,respectively.One QTL locus related to S2 trait was distributed in LG3.In the closure time traits,14 loci were detected,which were located in linkage groups 4,9,16 and 17.Among them,two QTLs related to S6 trait,five QTLs related to S7,four QTLs related to S8 and three QTLs related to S9.The LOD values of all traits ranged from 2.74 to 5.83,mainly distributed in LG4 and LG9linkage groups,explaining 1.6%-47.48%of phenotypic variation.