ALA促进桃果实着色的生理与分子机制研究

5-aminolevulinic acid (ALA) is considered a new kind of plant growth regulators, which had been applied in production and stress resistance. In our previous work, the promotive effect of ALA on peach fruit coloring was found, but the regulatory mechanism of ALA on anthocyanin biosynthesis has not yet been elucidated. Therefore, the present study intends to take peach as test materials, and treat peach fruit with different concentration ALA. This study intends to conduct the following research content. (1) The effects of ALA on anthocyanin, sugar, acid, and amino acid of peach fruit, and discuss the physiological mechanism of promotion of ALA on fruit coloring would be studied through analysis the relation between the metabolism of sugar, acid and anthocyanin. (2) The effects of ALA on different endogenous hormones of peach fruit would be determined to reveal the physiological mechanism of promotion of ALA on fruit coloring at the hormone level. (3) The effects of ALA on the activities of key enzymes involved in anthocyanin biosynthesis would be investigated. This investigation aim to preliminary clarify the enzyme mechanism of promotion of ALA on fruit coloring. (4) At last, we are going to compare the differential expression of key genes related with anthocyanin biosynthesis among the different ALA-treated fruits, and then explore the molecular mechanism of promotion of ALA on fruit coloring.The results would provide the important theoretical base and practical guide for improving the quality of peach fruit.

5-氨基乙酰丙酸（ALA）被认为是一种新型的植物生长调节物质，在提高作物产量与抗逆性方面已有较多应用。申请者最近发现ALA具有促进桃果实着色的作用，但ALA调控桃果实着色的机理尚不清楚。为此，本项目拟以桃为试材，采用不同浓度ALA对桃果实进行处理，（1）研究ALA处理对桃果实花青素以及果实中糖、酸、氨基酸含量的影响，分析糖、酸、氨基酸与花青素含量的相关性，通过分析糖酸代谢与花青素代谢之间的关系探讨ALA促进果实着色的生理机制；（2）研究ALA处理对桃果实中内源激素的影响，从激素水平上解析ALA处理促进桃果实着色的生理机制；（3）分析ALA处理对果实花青素合成关键酶活性的影响，初步阐明ALA调控桃果实花青素积累的酶学机制；（4）通过比较不同浓度ALA处理下花青素合成关键基因表达水平的差异，进一步探讨ALA促进桃果实着色的分子机理。该研究结果可为提高桃果实外观品质提供重要的理论基础和实践指导。

桃树是我国重要的果树树种之一，桃果实的色泽是决定其品质的重要指标，本项目研究促进桃果实着色的调控措施具有重要的实践价值。本项目以桃果实为试材，采用不同浓度ALA（0、200、400 mg/L）对桃果实进行采前处理，研究结果表明ALA具有提高桃果实花青素含量和促进桃果实着色的作用，而且本试验通过研究ALA处理对桃果实糖酸代谢、相关酶活性、以及相关基因表达量的影响，探明了ALA促进桃果实着色的生理与分子机制。主要研究成果如下：（1）初步阐明了ALA促进桃果实着色的生理作用机制：ALA处理提高了桃果实光合作用产物、相关抗氧化酶活性、花青素含量，通过分析花青素含量与光合作用产物及抗氧化酶活性之间的相关性，初步揭示了ALA提高桃果实着色生理机制，同时也证实了ALA处理可作为一种有效的措施用于提高桃果实内在和外观品质。（2）从分子水平解析了ALA促进桃果实着色的分子机制：本项目克隆了桃果实花青素代谢过程中的重要结构基因与转录因子基因PpANS、PpUFGT、PpCHS、PpF3H和PpMYB10、PpMYB44、PpbHLH3、PpWD40，并鉴定了关键基因参与桃果实花青素生物合成的功能，通过基因表达谱分析弄清了ALA通过调控桃果实花青素合成途径中关键基因表达量，进而促进桃果皮着色。（3）确定了桃果实花青素积累过程中的关键基因：利用RNA-seq技术分析了桃果实不同发育时期的转录组表达谱，检测了不同发育时期桃果皮花青素含量，初步筛选了与花青素积累密切相关的差异基因，通过探究花青素合成相关差异基因如PpANS的表达谱、体外酶活验证等，进一步确定了桃果实花青素合成途径中的关键基因，并鉴定了基因功能，为ALA调控桃果皮花青素含量进一步提供了理论基础。上述研究结果为进一步探明ALA促进桃果实着色的调控机制以及提高果实品质奠定了理论基础和实践指导。