The Molecular Basis Of Variegated Colour In Ornamental Peach

Ornamental peach is one of the ornamental plants,which flower is the important ornamental organ,and which color of the flower is of important ornamental value.At present,there are about 100 ornamental peach varieties in the world.It can appear on one plant,different color of flowers,the two color spots,stripes or the whole different flower color or the differences on the same position in different years.The Prunus Persica 'Sahong Tao' as the plant material was clarified the mechanism of the variegated color.Firstly,we detected the types of pigments of white buds(WF)and red buds(RF).Secondly,Illumina sequencing technology was employed to identify in libraries from the WF and RF flower buds of the cv 'Sahong Tao'.Thirdly,a combination of two-dimensional gel electrophoresis(2-DE)and matrix-assisted laser desorption/ionization time of flight/time of flight mass spectromrtry(MALDI-TOF/TOF MS)were used to identify the differentially expressed proteins between the WF and the RF.Finally,WGBS was used to analysis the influence of gene methylation in the color of peach from the epigenetics perspective.The main results were as follows:1.To detect the pigment type and content of flower buds,we used the specific color reactions,UV-visible spectra and the pH differential method.The results demonstrated that the anthocyanins are the main pigment in petals of Prunus persica.The red extract content of anthocyanins(0.122 mg/g)is significant higher than white one(0.066 mg/g).In the WF,the carotenoids content is 0.004 mg/g,and in the RF,the carotenoids content is 0.015 mg/g.Compared with the WF,the carotenoids content of RF is significant higher.However,the contents and distributed of anthocyanins and carotenoids could be the reason that result the different color in 'Sahong Tao'.2.We estimated gene expression with Illumina sequencing technology in libraries from the white(WF)and red(RF)flower buds.The results showed that 3,599,960 and 3,464,141 tags were sequenced from the two libraries,respectively.Moreover,we identified 106 significantly differentially-expressed genes between the two libraries.Among them,78 and 28 represented transcripts with a higher or lower abundance of more than two-fold than in the WF library,respectively.GO annotation revealed that highly ranked genes were those implicated in carbon-carbon lyase activity,carboxy-lyase activity,positive regulation of cell communication and the pigment biosynthetic process.The expression patterns of eleven genes were verified with quantitative RT-PCR assays.The results suggested that Hydroxycinnamoyl-Coenzyme A shikimate/quinate hydroxycinnamoyl transferase(HCT),flavanone-3-hydroxylase(F3H),Isoflavone reductase(IFR),Riboflavin kinase(RFK),Zeta-carotene desaturase(ZDS),and ATP binding cassette(ABC)transporter might be associated with the flower colour formation.3.More than 500 highly reproducible protein spots(P<0.05)were detected and 72 protein spots showed a greater than two-fold difference in their values.70 proteins were demonstratively identified,20 protein spots were up-regulated and 50 were down-regulated.Proteins identified were classified into eleven functional classifications.Energy related proteins(22.86%)ranked first,followed by metabolism(21.43%)and defense(14.29%)related proteins second and third,respectively.Among these proteins,LDOX,WD40,ACC,and PPO II are related to the pigment biosynthetic pathway.Moreover,most of the other proteins are involved in energy and metabolism,which provide energy and substrates.The four UCH proteins are involved in protein fate,and may be important in post-translational modifications in peach flowers.The three unknown proteins with increased expression in WF may represent novel proteins.Their functions and cellular localizations need further investigation.4.We sequenced 10.8 Gb of bisulfite-converted DNA,which yielded an average depth of 42.5 X for both two samples.The CG methylation level is 51.67%,and mCG is mainly concentrated in transcription regions.CHG and CHH showed lower methylation level in transcription regions contrast with upstream and downstream.We identified 189 differentially methylated regions by our analysis,and categorized them into twelve biological processes,six cellular components,three molecular functions.Associated with the digital gene expression profiling analysis,methylation level of gene body is higher than upstream and downstream,and silent genes has higher methylation level than expression genes.There were 23941(88.1%)methy genes and 3240(11.9%)unmethy genes in WF library,while 23806(87.6%)methy genes and 3365(12.4%)unmethy genes in RF library.And 8416 methy genes showed expression specificity between RF and WF.SBF transcription factor existed differentially in methylation level and expression level.Compared with the proteomics,52 different proteins has varying degrees methylation.