转录组和代谢组联合解析苹果采后高浓度CO2伤害机制

Analysis of apple postharment damage under high CO2 concentration by transcriptome combined with metabolome

摘要:

环境气体浓度影响果蔬的贮藏保鲜期和品质，高浓度CO2长时间处理会造成果实的伤害，但具体的分子机制不清楚。本研究以高浓度CO2处理采后富士苹果为材料，利用Illumina Hiseq 4000高通量测序技术和非靶向代谢技术分别对苹果内部褐变果肉组织和对照组正常果肉组织进行转录组测序和代谢组学分析，解析苹果CO2伤害产生的机制。结果如下：转录组测序共获得6 332个差异基因，包括4 187个上调基因和2 145个下调基因。差异基因进行功能性分析初步确定苹果CO2伤害的发生与氧化还原过程、脂类代谢、激素信号转导过程、能量代谢过程有关，并成功筛选出20个候选褐变基因，其中grxcr1 (MD14G1137800)、gpx (MD06G1081300) 参与活性氧清除过程，pld1_2 (MD15G1125000) 和plcd (MD07G1221900) 参与磷脂酸合成，影响膜代谢，mdh1 (MD05G1238800) 参与TCA循环，影响能量代谢。代谢组分析共获得77个差异代谢物，主要是有机酸、脂类、糖类和多酮类化合物，其中包括35个与褐变相关的代谢物质。将差异基因和差异代谢物进行联合分析，结果显示，类黄酮生物代谢过程参与了苹果的褐变过程，褐变组织与对照组织比较发现儿茶素、槲皮素等黄酮类含量明显下降，细胞抗氧化能力下降，氧化还原状态失衡，细胞结构破坏，造成褐变。本研究结果进一步丰富了CO2伤害产生的理论基础，同时为高浓度CO2保鲜技术的实际应用提供理论指导。

Abstract:

The environmental gas concentration affects the storage period and quality of fruits and vegetables. High concentration CO2 treating for a long time will cause damage to fruits, However, the specific molecular mechanism is unclear. To analyze the mechanism of CO2 injury in apple, high-throughput sequencing technology of Illumina Hiseq 4000 and non-targeted metabolism technology were used to analyze the transcriptome sequencing and metabolomics analysis of browning flesh tissue of damage fruit and normal pulp tissue of the control group. A total of 6 332 differentially expressed genes were obtained, including 4 187 up-regulated genes and 2 145 down regulated genes. Functional analysis of the differentially expressed genes confirmed that the occurrence of CO2 injury in apple was related to redox process, lipid metabolism, hormone signal transduction process and energy metabolism process. Twenty candidate browning genes were successfully screened, among which grxcr1 (md14g1137800) and gpx (md06g1081300) participated in the reactive oxygen species scavenging process, and pld1_ 2 (md15g1125000) and plcd (md07g1221900) participated in phospholipid acid synthesis and affected membrane metabolism. mdh1 (md05g1238800) participated in TCA cycle and affected energy metabolism. A total of 77 differential metabolites were obtained by metabolomic analysis, mainly organic acids, lipids, sugars and polyketones, including 35 metabolites related to browning. The metabolism of flavonoids was involved in the browning process of apple. Compared with the control tissue, the content of flavonoids such as catechin and quercetin decreased significantly in the damaged apple tissue, the antioxidant capacity of cells decreased, the redox state was unbalanced, and the cell structure was destroyed, resulting in browning. The results of this study further enrich the theoretical basis of CO2 damage, and provide reference for the practical application of high concentration CO2 preservation technology.