Study On The Expression Differences Of The Genes Involved In Anthocyanin Biosynthetic Pathway During The Coloration Process In Peach Flowers And Leaves Of Different Cultivars

The newly germinating leaves of red-leaf peach are brilliant red in spring, but they would turn green under the high tempreture condition in summer, as leaf age increasing, the basal leaves gradually turn from dark red to green, anthocyanin content decrease. In contrast, many early maturing peach varieties have dark green leaves before fruit harvest, and anthocyanin accumulation starts in the leaf petiole, main vein and spread along the vein. Leaf color gradually turns to purple-red from the basal leaves to the top. Because of the speciality of its leaf coloring, these peach cultivars have important theoretical and practical significance to the development and application prospects in gardening, but also on enriching the research of color emerging mechanism in colored-leaf plants.This research selected two red leaf color peach cultivars (’Zhubo-5’,’Red-leaf peach’) and two early maturing peach cultivars (’Zaomei’,’Chunlei’), which leaves turn red in summer, as the trail materials, green leaf peach cultivar’Honghua-2’and’Jingmi’as CK. We analyzed and compared their anthocyani contents, color changes and the expression of the last four genes involved in the anthocyanin biosynthetic pathway in their flowers and leaves. The flowers of each cultivar were sampled at the flowering initiation, full-blooming stage and the late florescence. The leaves were sampled during their growth season (May to September). The four genes are flavanone3-hydroxylase (F3H), dihydroflavonol4-reductase (DFR), leucoanthocyanidin dioxygenase (LDOX) and UDP-glucose:flavonoid3-O-glucosyltransferase (UFGT). This research studied physiological mechanism of flower color change, leaf color change of peach with different coloration type cultivars, and the impact on the coloration of the expression levels of the four genes. The main results of the study are as follows:1、Based on the nucleotide sequences of UDP-glucose:flavonoid3-O-glucosyltransferase (UFGT) involved in the anthocyanin biosynthetic pathway deposited in Genebank, four pairs of primers were designed. All the PCR products were ligated to pMD18-T vector and then the recombinant vector was transformed into Ecoli DH5a strain. The anticipated clones checked by PCR were cultured and sent for sequencing. The open reading frame sequences of UFGT and the deduced amino acid sequences were aligned with their corresponding homologues deposited in Genebank, and phylogenetic tree was constructed. The results indicated that the nucleotide and amino acid sequences of UFGT in different fruit trees were highly similarity, suggesting they evolved in different directions.2、To elucidate the connection between flower coloration and expression of genes related to the anthocyanin biosynthetic pathway, the expression of the last four genes:F3H, DFR, LDOX, UFGT, which involved in the anthocyanin biosynthetic pathway during peach flower development determined. The results showed that the four genes have certain roles in anthocyanin synthesis and flower color formation. F3H, DFR, and UFGT have a positive correlation with anthocyanin content. However, LDOX gene may have no direct relationship associated with peach color forming. The results of this study laid a foundation for understanding the molecular mechanism of peach flower development and the role of related genes in peach coloring process.3、In this experiment, quantitative real-time RT-PCR was employed to analyzee the four related genes in the anthocyanin biosynthetic pathway in peach leaves of six different cultivars during the growing season. The results show that a close relationship between the level of anthocyanin content and the color changes of peach leaf. There is also a positive correlation between the anthocyanin content of peach leaves with the value of leaf color chroma a*.The expression levels of the four genes involved in anthocyanin biosynthetic pathway were positively correlated with the anthocyanin content in leaves. The expression levels also had a close relationship with red color of peach leaves. This research has important theoretical significance on insighting into the molecular mechanisms of peach leaf coloration and the utilization of the related genes in genetic engineering, and for some positive control on their expression to regulate the leaf color.