GABA诱导桃果实采后抗冷性的机制研究

Peach fruit is very perishable due to microbial decay and mechanical damage after harvest. Low temperature storage is an effective method to control postharvest decay and maintain fruit quality. However, chilling injury (CI), the major physiological disorder, limits the storage period and shelf life when peaches are stored at low temperature. Thus, alternative postharvest handlings to alleviate chilling and extend shelf life of peach are needed. Recently, we found that there was a close relationship between γ-aminobutyric acid (GABA) metabolism and chilling tolerance in postharvest peach fruit. Low temperature induced GABA accumulation in peaches and exogenous GABA alleviated CI in cold-stored fruit. However, the mode of action of GABA in reducing CI has not been clearly elucidated. This project will investigate the effect of GABA on ethylene biosyntheses and signal transduction as well as its anaplerosis role in tricarboxylic acid cycle in cold-stressed peaches with two different ripening stages to reveal the mechanism by which GABA induces chilling tolerance in peach fruit. The results of this project will be helpful not only to enrich the knowledge and insight of CI in postharvest fruit but also to provide theoretical support for chilling tolerance regulation and development of new storage techniques in peach storage and transportation.

采后桃果实容易受到机械伤及病原菌侵染，低温冷藏可有效抑制果实采后腐烂。但桃果实属于冷敏性果实，对低温环境较敏感，在低温下贮藏较长时间易引起冷害。因此，研究桃果实采后冷害调控技术及其作用机理，已成为解决桃果实贮运保鲜问题的关键。我们前期研究发现γ -氨基丁酸（GABA）代谢与桃果实采后抗冷性密切相关。低温可以促进桃果实中GABA的积累，外源GABA 处理能够显著提高果实的抗冷性。但GABA 对冷敏感果实采后抗冷性调节机制仍不清楚。本项目以不同成熟度桃果实为试材，通过生理生化及分子生物学手段，研究在低温胁迫下GABA 对乙烯合成与信号转导的调控及对三羧酸循环的回补作用，以此来解释GABA 在调控桃果实采后抗冷性中的机制。该项目的研究不仅丰富了果实采后冷害相关知识及理论，同时为桃果实采后抗冷性的调控及保鲜新技术的开发提供了理论基础，因此本项目的实施具有重要的理论和应用价值。

桃是我国重要特色水果，果实柔软多汁、风味浓郁、营养丰富，深受消费者喜爱。桃为典型的跃变型果实，由于采收期适逢高温季节，果实采后在常温下迅速进入呼吸跃变期，成熟和衰老进程加快，果肉迅速软化，并伴随果肉褐变和风味劣变等现象的出现，软化了的果实又极易受到机械损伤和病原微生物侵染而导致大量腐烂。因此，桃果实常温贮藏期极短，影响了鲜果的流通和销售。低温冷藏能有效抑制桃果实后熟软化和腐烂，延长贮藏寿命。但桃果实属于冷敏性水果，低温下贮藏会发生冷害，其症状表现为果实色泽暗淡、香气减少、果心褐变、果肉粉质化或糠化、果汁减少、失去后熟作用和丧失风味等。桃果实冷害的发生不仅降低了果实的食用价值和商品性，还限制了桃果实的冷藏期和供应期。研究桃果实冷害发生的控制技术及其机理，已成为解决桃果实贮运保鲜问题的关键。因此，本项目以南方水蜜桃为试材，通过生理生化及分子生物学手段，研究了在低温胁迫下外源GABA处理对乙烯合成与信号转导的调控作用及对三羧酸循环的回补作用，并证实乙烯，脯氨酸，多胺及GABA自身的回补作用在GABA提高桃果实采后抗冷性的关键作用，以此来解释GABA在调控桃果实采后抗冷性中的机制。该项目的实施不仅丰富了采后桃果实冷害相关知识和理论，而且还为控制桃果实贮藏过程中品质劣变提供了理论依据。项目执行期间，主要成员分工协作，使计划研究任务得以顺利如期完成，并合作发表SCI 5 篇。