Red coloration contributes to fruit quality and is determined by anthocyanin content in peach (Prunus persica). Our previous study illustrated that anthocyanin accumulation is strongly regulated by light, and the effect of induction differs according to light quality. Here we showed that both ultraviolet-A (UVA) and ultraviolet-B (UVB) irradiation promoted anthocyanin biosynthesis in “Hujingmilu” peach fruit, and a combination of UVA and UVB had additional effects. The expression of anthocyanin biosynthesis and light signaling related genes, including transcription factor genes and light signaling elements, were induced following UV irradiation as early as 6 h post-treatment, earlier than apparent change in coloration which occurred at 72 h. To investigate the molecular mechanisms for UVA- and UVB-induced anthocyanin accumulation, the genes encoding ELONGATED HYPOCOTYL 5 (HY5), CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1), Cryptochrome (CRY), and UV RESISTANCE LOCUS 8 (UVR8) in peach were isolated and characterized through functional complementation in corresponding Arabidopsis (Arabidopsis thaliana) mutants. PpHY5 and PpCOP1.1 restored hypocotyl length and anthocyanin content in Arabidopsis mutants under white light; while PpCRY1 and PpUVR8.1 restored AtHY5 expression in Arabidopsis mutants in response to UV irradiation. Arabidopsis PpHY5/hy5 transgenic lines accumulated higher amounts of anthocyanin under UV supplementation (compared with weak white light only), especially when UVA and UVB were applied together. These data indicated that PpHY5, acting as AtHY5 counterpart, was a vital regulator in UVA and UVB signaling pathway. In peach, the expression of PpHY5 was up-regulated by UVA and UVB, and PpHY5 positively regulated both its own transcription by interacting with an E-box in its own promoter, and the transcription of the downstream anthocyanin biosynthetic genes chalcone synthase 1 (PpCHS1), chalcone synthase 2 (PpCHS2), and dihydroflavonol 4-reductase (PpDFR1) as well as the transcription factor gene PpMYB10.1. In summary, functional evidence supports the role of PpHY5 in UVA and UVB light transduction pathway controlling anthocyanin biosynthesis. In peach this is via up-regulation of expression of genes encoding biosynthetic enzymes, as well as the transcription factor PpMYB10.1 and PpHY5 itself.

红色会影响果实的品质，取决于桃子中花青素的含量（樱桃李）。我们以前的研究表明，花色苷的积累受光的强烈调节，并且诱导的效果根据光的质量而有所不同。在这里，我们表明，紫外线-A（UVA）和紫外线-B（UVB）辐射均能促进“虎颈mil”桃果实中花色苷的生物合成，而UVA和UVB的组合还具有其他作用。花色素苷生物合成和光信号传导相关基因的表达，包括转录因子基因和光信号传导元件，在处理后6 h进行紫外线照射后被诱导，比在72 h发生的明显的表观变化更早。为了研究UVA和UVB诱导的花色素苷积聚的分子机制，编码了长双氢代果糖5（HY5），组成型光致发光1（COP1），隐色（CRY）的基因，拟南芥）的突变体。 PPHY5 和 PpCOP1.1在白光下恢复了拟南芥突变体的胚轴长度和花色苷含量；而PpCRY1 和 PpUVR8.1 恢复 在HY5在紫外线辐射下拟南芥突变体中的表达。拟南芥PpHY5 / hy5转基因品系在添加紫外线（仅与弱白光相比）下积累了更多量的花色苷，尤其是当同时使用UVA和UVB时。这些数据表明，作为AtHY5对应物的PpHY5是UVA和UVB信号通路中的重要调节剂。在桃子中，PPHY5 通过UVA和UVB上调，PpHY5通过与自身启动子中的E-box相互作用以及下游花色苷生物合成基因的转录而正向调节其自身的转录 查尔酮合酶1 （PchCHS1）， 查尔酮合酶2 （丙二醛），以及 二氢黄酮醇4-还原酶 （PdDFR1以及转录因子基因 PpMYB10.1。总之，功能性证据支持PpHY5在控制花色苷生物合成的UVA和UVB光转导途径中的作用。在桃子中，这是通过上调编码生物合成酶的基因以及转录因子的表达来实现的PpMYB10.1 和 PPHY5 本身。