NO和SA互作在芒果采后衰老和抗病性诱导中的作用机制

Salicylic acid (SA) and nitric oxide (NO) are important signaling molecules in plant and play a crucial role in the regulation of normal plant growth and development processes. As potent signaling molecules in plants SA and NO are involved in eliciting specific responses to biotic and abiotic stresses. However, there was little report on the mechanism and inter-relationship between NO and SA during postharvest storage and diseases resistances. Mangoes are climacteric and ripen rapidly after harvest. Disease susceptibility and perishability due to ripening and softening limit the storage, handling and transport potential of the fruit. At present, the effects of NO and SA on the delaying senescence and diseases resistances during Mangoes storage has not been well investigated. In this project, the effects of NO and SA on the storage characters, physiology metabolism and disease resistance of postharvest mango will be investigated. And the mechanism of the single and interaction effect of NO and SA on the maintaining fruit quality, delaying senescence and inducing disease resistance will be also characterized. Furthermore, we clarify the relationship between NO and SA during the senescence and disease resistance induction of postharvest mango. Based on these results, it can provide the theoretical proof and technology reference on using NO and SA as preservative.

一氧化氮（NO) 和水杨酸（SA)都是普遍存在于植物体内的内源信号分子，能够调节植物的生长和发育，在植物对生物胁迫和非生物胁迫应答的信号转导过程中扮演着重要的角色。但是，关于NO和SA在园艺产品采后贮藏保鲜和抗病中的互作关系和相关机制的研究报告甚少，许多问题尚不清楚。芒果为典型的呼吸跃变型水果，采后生理代谢异常活跃，后熟和衰老进程快，极易感染病害，造成大量果实的腐烂变质，使果实的有效储藏期和货架期缩短，而目前尚缺少有关NO和SA应用于芒果保鲜和抗病的报道。本项目在明确NO和SA能够有效维持芒果果实品质、降低病害发生等作用效果的基础上，着重开展SA和NO互作处理对芒果果实采后贮藏特性、生理代谢和抗病性诱导等方面的研究，旨在明确SA和NO在采后芒果衰老和抗病性诱导过程中作用效果和相关机理，揭示其相互作用关系，为SA和NO应用于果实采后贮藏保鲜提供理论依据和技术支持。

芒果采后极易后熟软化、感染病害，从而导致果实品质降低、腐烂发生，造成巨大的经济损失。本研究以采后芒果果实为研究材料，通过研究外源硝普钠（SNP，NO供体）和SA单独或协同处理对采后芒果果实保鲜效果、活性氧代谢、乙烯合成代谢、细胞壁代谢和病害发生等的影响，探讨NO和SA在延缓芒果后熟衰老和抗病反应中的作用机制。主要研究结果如下：.1.SA或SNP处理可以明显延缓采后芒果果实的成熟衰老，提高果实的贮藏品质、降低采后病害的发生，且二者均具有明显的浓度效应，即低浓度促进高浓度抑制。.2.与单独SA或SNP处理相比，SA+SNP复合处理进一步延缓果实后熟转黄，维持果实中较高的可滴定酸和VC含量，延缓可溶性固形物和可溶性糖含量的增加，降低果实的失重和病害指数。而NO清除剂CP或SA合成抑制剂CA会不同程度的削弱SA或SNP处理对果实贮藏品质的维持效果，表明SA和NO在芒果贮藏保鲜中具有明显的互作增效的作用。.3.SA或SNP处理可以明显提高果实中的自由基清除能力，维持果实中较高的总的抗氧化能力和还原力，并且SA+SNP复合处理优于SA或SNP单独处理效果。进一步研究表明，SA或SNP延缓果实成熟衰老与其提高果实中抗氧化酶活性，降低LOX活性，抑制O2.-自由基产生和MDA积累有关，且SA+SNP复合处理效果优于单独处理，而NO清除剂或SA合成抑制剂则会不同程度的削弱SA或SNP单独处理的效果，表明SA和NO在提高果实抗氧化能力方面具有明显的互作作用。.4.SA或SNP通过抑制采后芒果果实中的ACO和ACS活性，从而减少ACC合成和乙烯含量；明显降低贮藏果实中主要水解酶活性，减少细胞壁果胶和纤维素的降解，从而延缓果实硬度的降低，且以SA+SNP复合处理的抑制程度大于SA或SNP单独处理。而CP或CA处理降低了SA或SNP的抑制程度，且以NO清除剂对乙烯合成代谢和细胞壁水解酶活性影响较大。.5.SNP、SA和SNP+SA处理明显增加了贮藏芒果果实中NO和SA含量及NOS活性，且以SNP+SA处理尤为明显。进一步分析表明，贮藏期间，SA峰值