Primary Study On The Mechanism Of Variegated Color In Ornamental Peach ’Jinlingjintao’

People love ornamental peach flower because of its rich, diversity and bright color. There are about 100 domestic and foreign ornamental peach accessions. A peach,’PCM-1’, with variegated color was obtained in breeding practice of ornamental peach at National Fruit Germplasm Repository for peach in Nanjing. The secondary color color was pink and white on flower, purple and green on leaf, and irregular red spots or dots on young fruits with green background. By grafting, most clones carried variegated color predicting the trait could be transmitted by grafting, but a few clones with pure color were also isolated. By sexual reproduction, individuals with variegated color were observed. In order to elucidate the molecular mechanism of ’PCM-1’, SSR was used to identify parent of ’PCM-1’ and difference among grafted clones; cDNA-AFLP was employed to investigate differentially expressed genes of petals from the isolated clones with different color. RNA-Seq was used to analyse differentially expressed genes of ’PCM-1R’ and’PCM-1G’ The results showed as follows:1. The parent of ’PCM-1’ was identified with 20 fluorescent SSR markers in 15 ornamental peach varieties.’PCM-1’,’PCM-1R’ and ’PCM-1G’ have been screened with 174 SSRs and 150 fluorescent SSR markers. The results showed that ’HongFenJiaRen’(a released ornamental peach) was identified to be the female parent of’PCM-1’and no different alleles were observed among three clones,’PCM-1’,’PCM-1R’ and ’PCM-1G’, although their leaf color are variegated, pure purple and green, respectively.2. The key factors affecting cDNA-AFLP analysis system was studied, an optimized cDNA-AFLP analysis system for peach was established, and a distinct electrophoretogram of cDNA-AFLP was obtained. The results indicated that total RNA extracted by the modified CTAB method had high purity and integrity; Optimal results was obtained in following steps:an initial 30-cycle preamplification PCR by using 2.0μL ligation products as template and the preamplification products diluted to 10 times for selective amplification in 20μL reaction volume.3. cDNA-AFLP technique was employed to investigate differentially expressed genes of ’PCM-1R’ and ’PCM-1G’. The polymorphic transcription-derived fragments (TDFs) were cloned, sequenced and functionally annotated. Blastx analysis and functional annotations were then performed and the results revealed that seventeen TDFs were homologous with known proteins. Among the 17 TDFs,8 TDFs were involved in signal transduction,5 in metabolize,2 in cell differentiation,1 in photosynthesis, and 1 in transcriptional control.4. Twelve homologous genes clearly annotated in peach genome, from differentially expressed fragments separated by cDNA-AFLP approach, were selected for real-time fluorescence quantitative PCR experiments. The results showed that 5 genes at high expression level in genotypes with white flower and green leaf were ppa005282m, ppa025850m, ppa001038m, ppa010768m, and ppa023284m. Two genes at high expression level in genotypes with the pink (or red) flower and purple leaf were ppa007494m and ppa015603m.5. Analysis differentially expressed genes from transcriptome of ’PCM-1R’ and ’PCM-1G’. The results showed:419 differentially expressed genes between the ’PCM-1R’ and ’PCM-1G’,160 genes up-regulated,259 down-regulated genes in ’PCM-1R’. KEGG biological pathway analysis revealed 15 differentially expressed genes involved in flavonoid biosynthesis pathway. It was supposed that ’PCM-1R’ and ’PCM-1G’ with different color are the result of interaction of multiple genes.