非光敏型茄子果皮着色机理及相关基因调控路径研究

The peel color is one of the most important commodity characters for eggplant. The traditional eggplant cultivars in China have good edible quality, but the peel coloring is sensitive to light, while the peel coloring of some European varieties is non-photosensitive. The weak coloring of eggplant commodity fruit has become the bottleneck of localization of protected cultivars with the rapid development of the protected vegetable cultivation. In this work, the autonomously bred no-photosensitive peel coloring line 10683 and photosensitive peel coloring line 08530 were used as materials. To find the peel pigment metabolites group features and define the character and concentration of specific maker, the composition, molecular structure and content of the peel coloring metabolites in the two type of materials are compared by modern metabonomics detection and analysis techniques such as HPLC-DAD and HPLC-UV-MS/MS. Expression profiles of the regulatory genes for peel coloring are investigated in both non-photosensitive and photosensitive lines by Real-time fluorescent quantitative PCR, and some key candidate genes are identified. Then the full-length cDNA and promoter are cloned and analyzed of each candidate gene, and the underlying regulatory mechanisms are researched. The clarifying of biochemical and molecular mechanisms of peel coloring in eggplant can provide us technical practices and theoretical basis for identification fruit coloring mechanism of horticultural crops .

果实外观色泽是茄子重要的商品品质性状，我国传统茄子品种食用品质优良，但是果皮着色对光照十分敏感，而有些进口的欧洲茄子品种果皮着色不受光照强弱的影响。如今设施蔬菜栽培迅猛发展，商品果着色差已成为限制保护地栽培茄子品种本土化的瓶颈。本项目拟以自主选育的非光敏型果皮着色茄子品系10682和光敏感型品系08530为材料，利用HPLC-DAD和HPLC-UV-MS/MS等现代代谢组学检测分析技术，通过分析果皮着色代谢产物组分、分子结构和含量，明确不同生态型茄子果皮色素代谢物群体特征和特定标记物的性质和浓度；利用荧光定量PCR的方法，分析非光敏型/光敏感型茄子果皮着色调控关键基因的转录表达特点，寻找决定茄子果皮颜色的关键候选基因，并对候选基因进行cDNA全长和启动子的克隆和分析，通过非光敏型茄子果皮着色相关基因调控路径研究，探讨其果皮颜色形成机理。为阐明园艺作物果实外观色泽形成分子调控机制奠定基础。

茄子果实外观色泽是茄子重要的商品品质性状，如今设施蔬菜栽培迅猛发展，弱光条件下商品果着色差已成为本土紫黑色长茄品种设施生产的瓶颈。影响茄子果皮着色代谢组分的鉴定、控制茄子着色基因的挖掘、和茄子着色调控机理的研究，对指导设施茄子品种的育种工作具有十分重要的意义。本项目通过研究光敏型茄子和非光敏型茄子花青苷、叶绿素和类胡萝卜素的总量，确定茄子的主要色素种类是花青苷，花青苷的含量与果皮颜色极显著相关。利质谱和核磁分析明确，本项目选用的非光敏型茄子的主要的花青苷单体是飞燕草-3-芸香苷，光敏型茄子的主要花青苷种类是飞燕草-3-对香豆酰芸香苷-5-葡萄糖苷。通过转录组测序和荧光定量PCR分析，明确套袋降低了光敏型茄子果皮中花青苷合成途径中F3'5'H、DFR、ANS、UFGT-1、UFGT-2基因的转录表达，但提高了bHLH1～bHLH6基因的表达量。通过克隆和分析花青苷合成途径下游的DFR和UFGT-2基因的DNA全长序列，发现DFR和UFGT-2基因光敏型和非光敏型材料中完全一致，并且在启动子上都存在能与PIF3转录因子（能通过与光敏色素互作响应光照的bHLH类转录因子）互作的顺式作用元件，因此推测：光敏型茄子在套袋条件下PIF3转录因子高表达，并与DFR和UFGT-2基因的启动子结合，抑制其表达，导至花青苷不合成；非光敏型茄子中套袋和不套袋情况下PIF3的表达量都极少，所以DFR和UFGT-2基因不受抑制，花青苷的合成稳定。