Identification And QTL Analysis Of Flavonoids And Carotenoids In Rose Petals

Rose(Rosa cvs.)is the world’s most important ornamental plant,which can be widely used as cut flowers,potted plants and garden roses.The improvement of flower color is the most important breeding target of rose.However,due to the diversity of pigments in rose petals and the complexity of their structures,researches on the composition of flavonoids and carotenoids in rose petals are limited.On the other hand,because of double reduction and preferential pairing,traditional softwares for genetic linkage analysis cannot be deployed in tetraploid rose.Therefore,it is urgent to investigate the composition and genetic mechanism of pigments in petals of tetraploid rose.In this study,the compositions of anthocyanin,flavonol and carotenoid in petals of different colored cultivars and F1 hybrid population of tetraploid rose.High-density linkage map of was constructed by restriction-site associated DNA sequencing and genetic software for autopolyploid,and then the quantitative locis(QTL)for pigments content was analyzed.The main results are indicated as follows:(1)A total of 19 flavonols and 16 carotenoids were identified in yellow petals of ’Sun City’(2n=4x=28)by HPLC-PDA-MS,.among which three flavonols and 10 carotenoids were found for the first time in rose petals.The content of kaempferol 7-O-glucoside,kaempferol 3-O-rhamnoside and violaxanthin wsa high as 397.75μg/g FW,320.68 μg/g FW and 114.04 μg/g FW,respectively.The petal of’Sun City’ was shown to be a good source of flavonols and carotenoids.(2).A total of 4 anthocyanins were identified in petals of Rosa ’Yunzheng Xiawei’(2n=4x=28)and other 6 different colored rose cultivars,and the types of flavonols and carotenoids were same to that of ’Sun City’.The correlation and multiple linear regression analysis showed that anthocyanins especially pelargonidin 3,5-diglucoside played predominat roles in the formation of red hues of rose petals,and carotenoids especially(9Z)-violaxanthin mainly determained the yellow color of rose.Compared to carotenoids,anthocyanins played more important roles in the lightness of rose petals.(3)High throughput sequencing was carried out for ’Sun City’,’Yunzheng Xiawei’ and their 187 F1 progenies,and 17,382 SNP markers were detected by GATK.The dosages of SNP markers together with 381 SSR and AFLP marks were calculated by GATK in tetraploid model,and 6,885 high-quality marks were finally obtained.The high-density genetic linkage map of tetraploid rose was constructed by polymapR with 6,885 marks.This genetic linkage map comprising 6,842 makers distributed on seven linkage groups.The map spaned 1,158.90 cM with an average inter-marker distance of 0.18 cM.(4)The statistical analysis for 93 phenotypic traits of mapping population,including color parameters,anthocyanins,flavonols and carotenoids was conducted.All traits displayed continuous variation,the genetic variation coefficient ranged from 13.17%to 821.44%.A total of 282 QTL were identified by composite interval mapping method of polyqtIR software.Proportion of phenotypic variance explain for these QTL were from 11.15%to 55.99%.The results of QTL analysis on color parameters were consistent on the adaxial and the abaxial surface of petals in different years.There were 50 consensus QTL detected that were closely related to color parameters.The number of QTL for anthocyanins,flavonols and carotenoids were 40,113 and 79,respectively.Then,11 and 6 QTL clusters were detected for flavonoids and carotenoids,respectively.Further more,12 and 6 matkers were screened which were closely related to high content of flavonoids and carotenoids,respectively.Finally,41 and 20 candidate genes of flavonoid and carotenoid were selected from the physical positions of QTL cluster,respectively.In conclusion,this study was focused on the identification and quantification of anthocyanins,flavonols and carotenoids in rose petals,the construction of high-density linkage maps of tetraploid rose and the QTL mapping of pigment contents.These results would lay the foundation for molecular breeding of modern rose with important characters such as new color.Further more,these results could provide lessons for the genetic anlysis of other autopolyploidy plants.