蜡质损伤对采后青椒中叶绿素降解的影响机制研究

Color deterioration is an important restrictive factor for the storage and preservation of postharvest green peppers and chlorophylls is the main color pigment of green peppers. Exploring the mechanism of chlorophylls degradation for postharvest green peppers exhibits important theoretical and practical significance for proposing novel strategies to regulate the color deterioration in postharvest green peppers. There is a close relationship between chlorophylls degradation and the own characteristics of peppers during postharvest storage. Waxy, as the natural barrier of plant, it may play a key role for affecting the chlorophylls degradation during the postharvest of peppers. This study will firstly establish the kinetics of chlorophylls degradation for postharvest peppers regulated by artificial methods (dewaxing and protecting waxy) or the ones in the natural state. To explore the intrinsic relationship between waxy injury and chlorophylls degradation of postharvest peppers, the changes of “PaO” pathway, the modification of thylakoid membrane structure components and functions will be characterized in multiple levels. In addition, the stay-green gene (SGR) of green peppers will be cloned with reverse transcription-PCR (RT-PCR) and rapid-amplification of cDNA ends (RACE) molecular biology techniques, and the tissue expression specificities will also be characterized with semiquantitative PCR and real-time PCR methods, for exploring the regulation mechanism of waxy injury on chlorophylls degradation in postharvest green peppers.

颜色劣变是限制青椒采后贮运保鲜的重要因素。叶绿素作为青椒的主要呈色物质，探讨其采后降解机制对提出调控青椒颜色劣变新策略具有重要的理论和实践意义。采后青椒叶绿素的降解与其自身特性密切相关，其中作为植物天然屏障的蜡质层可能是影响叶绿素降解的关键因素。本项目通过研究人为调控（去蜡和护蜡）和自然状态下青椒采后贮藏过程中叶绿素的动态变化，建立其降解动力学，同时探究采后青椒的蜡质结构特性变化规律，比较叶绿素“脱镁叶绿酸a氧化酶（PaO）”降解途径及类囊体膜超微结构、组分和功能特性变化，从而确定蜡质损伤对叶绿素降解的影响。通过RT-PCR、RACE等技术克隆青椒护绿蛋白基因（SGR），利用半定量PCR和实时定量PCR技术研究其组织特异性表达，结合叶绿素降解酶系（CCEs）中相关酶基因表达及活性变化，明晰SGR基因对采后青椒叶绿素降解的调控方式，揭示蜡质损伤对采后青椒中叶绿素降解的影响机制。

颜色劣变是限制青椒采后贮运品质的关键因素，探讨青椒采后颜色相关品质变化机制对提出调控青椒贮运品质新策略具有重要的理论和实践意义。本项目通过研究青椒采后贮藏过程中叶绿素及其相关品质的变化，明确了青椒采后贮藏过程中的颜色劣变规律；并通过研究青椒采后贮藏过程中丙二醛、多酚氧化酶、过氧化物酶、过氧化氢酶、苯丙氨酸酶、不同果胶组分等变化，分析青椒采后贮藏过程中生理特性变化与颜色劣变的关系；对青椒表皮蜡质层进行离析制备，对其组成进行定性定量分析，明晰青椒蜡质层组分变化对其采后颜色劣变的影响，初步提出热激结合真空渗钙处理、低温动态气调贮藏青椒的新方法。同时，在前期研究的基础上，以模式植物菠菜作为研究对象，通过研究HHP处理对PSⅡ颗粒组分及功能的影响，进一步探究绿色蔬菜颜色保持的可能机制。项目执行期间，累计以第一作者或通讯作者发表论文10篇，其中SCI收录论文4篇，EI收录论文1篇；申请国家发明专利1件。项目整体超额完成立项指标。