基于钙调素响应冷信号的桃果实采后抗冷害机制研究

Chilling injury (CI) is a major physiological disorder in peach fruit during cold storage, which limits the storage period of peach fruit and the application of refrigeration. It is important to evaluate the mechanism and controlling method of CI both in theoretical basis and practical implications. Calmodulin (CaM), as calcium receptor proteins, participates the molecular regulation against cold stress and plays important roles in response to cold signal, transduction of downstream signal pathways and regulation of protein phosphorylation in plant. This study focused on the scientific issue of CaM responding to cold stress in cold-stored peach fruit, and commenced on the expression of CaM and CaM-binding transcription activator gene, proteomics analysis of Ca2+/CaM dependent protein phosphorylation and regulation of downstream transcription factor associated with cold signal pathways. Thus, this study is supposed to illuminate the signal pathways and metabolic network of CaM regulating the transduction of cold signal, and explain the key role as a bridge of CaM responding to cold stress in cold-stored peach fruit. Moreover, the results of this study can enrich the theory of CI regulation in postharvest biology, and provide theoretical principle in controlling CI and deterioration in peach fruit during cold storage.

冷害是桃等冷敏性果实采后贮藏发生的主要生理性病害，限制了桃果实贮藏寿命和冷藏技术的应用，研究桃果实采后冷害发生机制和调控措施具有重要的理论意义和应用价值。钙调素作为钙离子受体蛋白参与植物对低温等逆境胁迫的分子调控，钙调素在响应冷信号、下游信号通路转导和调节蛋白磷酸化等方面都具有重要功能。本项目以冷敏性桃果实试材，以钙调素对冷信号的响应和转导作为科学问题切入点，深入探究桃果实冷害发生过程中钙调素结合蛋白、钙调素转录因子、钙/钙调素依赖蛋白磷酸化和下游冷信号转录的差异表达，阐明钙调素在桃果实冷信号转导中的分子通路和代谢网络，揭示钙调素在桃果实响应冷信号的关键枢纽作用。本项目的研究成果可丰富果实采后冷害调控的生物学理论，为控制桃果实采后冷害劣变提供理论依据。

桃属于冷敏性果实，在冷藏期间易发生冷害，从而降低了果实的品质和价值，还严重限制了果实的冷藏期和货架寿命。因此，研究调控果实冷害发生的技术及其机理具有重要的理论和实际意义。本研究以桃果实为试验材料，采用生物信息学、分子生物学、转录组学、磷酸化蛋白组等技术分析了桃果实中钙调素和钙调素转录因子的生物学功能。研究了不同温度贮藏、热激、钙和钙调素拮抗剂处理，对桃果实冷藏过程中钙调素及其相关结合蛋白表达、钙调素转录因子基因表达、钙调素互作蛋白、钙调素下游调控基因的影响，系统研究了钙调素介导温度信号参与调控果实冷害的主要作用。此外，从果实品质变化、活性氧代谢、能量代谢、脯氨酸代谢、酚类和糖代谢、细胞膜组分变化等方面，研究了不同温度贮藏、热激、钙和钙调素拮抗剂处理对桃果实冷害调控的作用模式，从而阐明了桃果实中以钙调素和钙调素转录因子为中间桥梁，介导下游转录因子和活性氧信号传导的分子调控机制。这些研究结果证实了钙-钙调素复合体在桃果实响应温度信号过程中的关键作用；明确了钙调素、类钙调蛋白、钙调素转录因子之间存在相互作用关系；阐明了钙调素转录因子介导调控下游CBF和NAC转录因子，进而调控活性氧代谢网络，提高果实抗冷性，抑制冷害发生的分子机制；揭示了不同采后处理通过调控桃果实钙调素转录因子的磷酸化修饰，提高活性氧代谢、能量代谢、脯氨酸代谢、糖和酚类物质代谢途径，从而减轻冷害发生的主要机理。本研究丰富了果实采后冷害调控的生物学理论，对于挖掘果实响应低温胁迫的关键基因，进而从分子生物学水平进行调控果实冷害劣变提供理论依据。