| Photoperiod has an important role on the growth and development of plants.Brassica napus is a long day plant,a wide adaptability varietiy is benefit for the innovation of the germplasm resources of Brassica napus and could improve the adaptability of Brassica napus in different sowing seasons and latitude,which plays an important role in genetic improvement and breeding of rape.In the present study,a doubled haploid(DH)lines with 150 individuals were constructed from two Brassica napus cultivars,Bing 409 and Zhongshuang 8,which exhibited different reaction to photoperiod,Bing 409 is sensitivity to photoperiod and Zhongshuang 8 is not.the composite interval mapping method were used to conduct QTL mapping and analyze the effect on flowering time based on the genetic linkage map of the DH population.We planted the DH population in 6 environments in 3 years.In the meantime,Bing 409 and Zhongshuang 8 were planted in the climate chamber with different photoperiod treameat,the photoperiod parameters were 16 h light and 8h dark,12 h light and 12 h dark,the temperature was 23? in light and 20? in dark.After a month,we took leaves as samples,the time was 0h(the light begun),4h,8h,12 h,16h,20 h,24h?We extrated RNA and conducted RNA-seq to find the DEGs controlling the flowering time.Two repeats were made.The results are as below: 1.The QTL information about flowering time in the DH population under six environmentsIn three years,flowering time of the DH population were investigated in four locations(Wuhan,Hezheng,Wulumuqi,Shaoguan)including six different environments(three years*one location+one year*three location).A total of 11 QTLs related to flowering time were detected.We detected the same QTL on chromosome C8 in E1,E2,E3,E4,E5,E6.the average explained phenotypic variance reached to 11.31%.We detected the same QTL on chromosome A3 in E1,E2,E3,E6.the average explained phenotypic variance reached to 7.89%.And the same QTL on chromosom A2 was detected in E1,E3,E5,E6.the average explained phenotypic variance reached to 10.32%.Seven QTLs were detected in only one location.2.Analysis of photoperiod sensitivityWe conducted photoperiod sensitivity analysis according to the flowering time in different locations.A total of 11 QTLs related to photoperiod sensitivity were detected.The same QTL on chromosome A2 was detected in E1-E6,E2-E6,E3-E6,E3-E4,E4-E6 and E5-E6.the average explained phenotypic variance reached to 12.59%.The same QTL on chromosome C8 was detected in E1-E6,E2-E5,E2-E6,E3-E6,E4-E5,E4-E6.the average explained phenotypic variance reached to 17%.The same QTL on chromosome A3 was detected in E1-E6,E2-E4,E2-E6,the average explained phenotypic variance reached to 5.12%.The number of QTLs detected only in the comprision with two environments was 5.3.The RNA-seq analyse of Brassica napus under different photoperiod conditionsAnalysis of the relative expression of Bing 409 and Zhongshuang 8 under the same photoperiod and the same time,we found that most differentially expressed genes(19965 genes)were specially expressed at 24 h in the 16 h photoperiod,and most differentially expressed genes(18859 genes)were specifically expressed at T12 in the 12 h photoperiod.In the analysis of Bing 409 and Zhongshuang 8 in the different photoperiod at the same time respectively.we found most differentially expressed genes(20396 genes)were specially expressed at 24 h in Bing 409,and most differentially expressed genes(20237 genes)were specially expressed at 16 h in Zhongshuang 8.In the critical point of light and darkness differentially expressed genes were most.4.The analysis of candidate geneWe found 676 differentially expressed genes on chromosomeA2,A3 and C8 from the transcriptome data according to the QTL interval,the genes related to flowering were not found.In the KEGG analyse,starch and sucrose metabolism and purine metabolism contained most genes. |
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