外源NO对马铃薯块茎创伤木栓化的影响机制

Potatoes（Solanum tuberosum L.）are the fourth major global food crop, which are usually wounded during harvest, handling, and seed cutting. Wounds could make the quality of seed tuber decreased. Wound-induced suberization and development of a hydrophobic matrix to reduce water vapour loss at the wound site are the more important defect action among the major wound-healing processes. However, the expression of some genes which may be involved in wound periderm development and maturation are not fully understood and little is known about the relevant regulatory mechanism of hormone and Nitric oxide on wound-healing processes.. This project is based on NO-treatment on cut potato tubers to investigate the following items：(1)the effect of NO on the molecular mechanism of wound periderm development and maturation.(2) the mechanism between plant hormone and signaling molecule during potato tuber wound-healing response. (3) the biological factors regulating the wound-healing process or the putative regulators hastening these processes. This project could contribute to illuminate the regulatory mechanism of potato wound-healing process,and find some biological factors regulating wound-healing process or hastening these processes, and promote the potential economic values in seed tuber production.

马铃薯作为全球第4大粮食作物，其块茎在收获、处理和种薯切块等过程中极易受到损害，造成块茎商品品质和种薯质量下降。马铃薯块茎创口处的细胞木栓化和防水层的快速累积是块茎防止感染和皱缩的重要防护反应，目前针对创伤木栓化的相关基因表达、植物内源激素和一些信号分子对马铃薯块茎创伤愈合的研究还处于空白。本研究以外源NO处理切块的马铃薯块茎，研究（1）了解外源NO对马铃薯块茎创伤周皮影响的分子机制。（2）了解植物内源激素与外源NO信号分子间的关联机制。（3）了解影响马铃薯块茎创伤愈合反应的关键因子。项目实施有助于阐明马铃薯块茎创伤木栓化的机制，阐释影响马铃薯块茎创伤愈合反应的关键因子，利用研究成果可人工调控马铃薯块茎创伤后木栓化进程，对马铃薯商品生产和种薯生产具有较大的经济价值。

马铃薯块茎创伤后会在伤口处诱导栓化愈合反应，在伤口表面形成封闭层和创伤周皮，抑制水分散失和病原菌侵染，维持块茎的正常生理。但自然条件下，创伤周皮完全形成所需的时间较长，不利于马铃薯的储藏和品质保证，必须采取措施促进创伤愈合。NO是植物体内普遍存在的信号分子，在植物抗逆生理中担任重要的角色。本项目研究结果表明外源NO处理可以上调苯丙烷代谢、木质素代谢、苯丙氨酸代谢、类黄酮生物合成代谢和脂肪酸代谢等代谢途径，上调PAL、4CL、C4H、POD、LAC、FLS、LDOX、Tsc13p、PATE、LOX、ACP和CYPS等基因表达，提高PAL、C4H、4CL和POD等苯丙烷代谢相关酶的活性，促进块茎创伤后软木脂、木质素、类黄酮、总酚和软木脂的累积，加快封闭层的形成，从而促进创伤后的栓化愈合。而C-PTIO处理后对这些酶酶活和代谢物含量累积有抑制作用，进而抑制伤口的愈合。外源NO处理可以上调活性氧相关代谢代谢、谷胱甘肽代谢等代谢途径，上调SOD、CAT、GST等基因的表达，提高SOD、CAT、POD、APX和GR的酶活性，提高组织中的ASA含量，抑制NOX的酶活性，降低MDA的累积，从而增加块茎组织对ROS的抗性，清除在机械创伤胁迫下组织过度产生的ROS。C-PTIO处理可以抑制SNP对这些酶和抗性物质的作用。外源NO处理可以促进如植物激素信号转导通路、植物MAPK信号通路和Ca2+信号转导通路等植物信号转导途径的激活，上调SABP、MAPKKK、PP2C、EIL1、JA2、CBP和IAAS GH3.6等基因的表达，促进植物对创伤的应激，提高植物的抗性。