qRT-PCR analysis of the expression profiles of anthocyanin structural genes (A) and <i>PcMYB10</i> genes (B) in petals of cv.

<p>Ziyeli and Aoben.</p

Constitutive Activation of an Anthocyanin Regulatory Gene <i>PcMYB10</i>.<i>6</i> Is Related to Red Coloration in Purple-Foliage Plum

<div><p>Cherry plum is a popular ornamental tree worldwide and most cultivars are selected for purple foliage. Here, we report the investigation of molecular mechanism underlying red pigmentation in purple-leaf plum ‘Ziyeli’ (<i>Prunus cerasifera</i> Ehrhar f. atropurpurea (Jacq.) Rehd.), which shows red color pigmentation in fruit (flesh and skin) and foliage. Six anthocyanin-activating MYB genes, designated <i>PcMYB10</i>.<i>1</i> to <i>PcMYB10</i>.<i>6</i>, were isolated based on RNA-Seq data from leaves of cv. Ziyeli. Of these <i>PcMYB10</i> genes, five (<i>PcMYB10</i>.<i>1</i> through <i>PcMYB10</i>.<i>5</i>) show distinct spatial and temporal expression patterns, while the <i>PcMYB10</i>.<i>6</i> gene is highly expressed in all the purple-coloured organs of cv. Ziyeli. Constitutive activation of <i>PcMYB10</i>.<i>6</i> is closely related to red pigmentation in the leaf, fruit (flesh and skin), and sepal. However, the <i>PcMYB10</i>.<i>6</i> activation cannot induce red pigmentation in the petal of cv. Ziyeli during late stages of flower development due to due to a lack of expression of <i>PcUFGT</i>. The inhibition of red pigmentation in the petal of cherry plum could be attributed to the high-level expression of <i>PcANR</i> that directs anthocyanidin flux to proanthocyanidin biosynthesis. In addition, <i>PcMYB10</i>.<i>2</i> is highly expressed in fruit and sepal, but its expression cannot induce red pigmentation. This suggests the <i>PcMYB10</i> gene family in cherry plum may have diverged in function and <i>PcMYB10</i>.<i>2</i> plays little role in the regulation of red pigmentation. Our study provides for the first time an example of constitutive activation of an anthocyanin-activating <i>MYB</i> gene in <i>Prunus</i> although its underlying mechanism remains unclear.</p></div

qRT-PCR analysis of the expression profiles of anthocyanin structural genes (A) and <i>PcMYB10</i> genes (B) in fruit flesh of cv.

<p>Ziyeli and Aoben.</p

qRT-PCR analysis of the expression profiles of anthocyanin structural genes (A) and <i>PcMYB10</i> genes (B) in leaves of cv.

<p>Ziyeli and Aoben.</p

qRT-PCR analysis of the expression profiles of anthocyanin structural genes (A) and <i>PcMYB10</i> genes (B) in sepals of cv.

<p>Ziyeli and Aoben.</p

Pigmentation phenotype in flowers (A), leaves (B), and fruits (C) of two cherry plum cultivars Ziyeli and Aoben.

<p>FW1, flower buds at pink stage; FW2, flower buds at the bloom stage; FW3, flowers at full bloom. DAFB, days after full bloom.</p

Phylogenetic tree derived from nucleotide acid sequence of anthocyanin-activating <i>MYB</i> genes in plants.

<p>Anthocyanin-activating <i>MYB</i> genes isolated in this study are highlighted in grey color. The GeneBank Accession numbers of these <i>MYB</i> genes are as follows: <i>Arabidopsis thaliana AtMYB75</i> (AF062908), <i>AtMYB90</i> (AF062915), <i>AtMYB113</i> (NM_105308), and <i>AtMYB114</i> (AY008379); <i>Malus × domestica MdMYB1</i> (AB744001) and <i>MdMYB10</i> (EU518249); <i>Prunus persica PpMYB10</i>.<i>1</i> (ppa026640m), <i>PpMYB10</i>.<i>2</i> (ppa016711m), <i>PpMYB10</i>.<i>3</i> (ppa020385m), <i>PpMYB10</i>.<i>4</i> (ppa018744m), <i>PpMYB10</i>.<i>5</i> (ppa024617m), and <i>PpMYB10</i>.<i>6</i> (ppa022808m); <i>Vitis vinifera VvMYBA1</i> (FJ687552) and <i>VvMYBA2</i> (DQ886419).</p

qRT-PCR analysis of the expression profiles of anthocyanin structural genes (A) and <i>PcMYB10</i> genes (B) in fruit skin of cv.

<p>Ziyeli and Aoben.</p

Assessment of Sugar Components and Genes Involved in the Regulation of Sucrose Accumulation in Peach Fruit

Soluble sugar contents in mature fruits of 45 peach accessions were quantified using gas chromatography analysis. Sucrose is the predominant sugar in mature fruit, followed by glucose and fructose, which have similar concentrations. Overall, sucrose metabolism and accumulation are crucial determinants of sugar content in peach fruit, and there is a wide range of sucrose concentrations among peach genotypes. To understand the mechanisms regulating sucrose accumulation in peach fruit, expression profiles of genes involved in sucrose metabolism and transport were compared among four genotypes. Two sucrose-cleaving enzyme genes (<i>SUS4</i> and <i>NINV8</i>), one gene involved in sucrose resynthesis (<i>SPS3</i>), and three sugar transporter genes (<i>SUT2</i>, <i>SUT4</i>, and <i>TMT2</i>) were prevalently expressed in peach fruit, and their expression levels are significantly correlated with sucrose accumulation. In contrast, the <i>VAINV</i> genes responsible for sucrose cleavage in the vacuole were weakly expressed in mature fruit, suggesting that the sucrose-cleaving reaction is not active in the vacuole of sink cells of mature peach fruit. This study suggests that sucrose accumulation in peach fruit involves the coordinated interaction of genes related to sucrose cleavage, resynthesis, and transport, which could be helpful for future peach breeding

Additional file 2 of A metabolic perspective of selection for fruit quality related to apple domestication and improvement

Additional file 2: Table S1. The list of collected 292 varieties. Table S2. Classification of 292 apple accessions. Table S3. Statistical results of heredity and variation. Table S4. Scheduled MRM transitions for widely targeted metabolite analysis in apple flesh. Table S5. Different metabolites identified between M. sieversii and heirloom groups. Table S6. Different metabolites identified between heirloom and cultivar groups. Table S7. Different metabolites identified among “Ralls Janet” and “Golden Delicious” series. Table S8. Different metabolites identified between low- and high-weight groups. Table S9. All significant SNPs for all apple metabolites Table S10. Candidate genes for tannins, lipids, SA, and ABA identified by GWAS. Table S11. Primers used in this study