【作者】 张飞；

【导师】 姜丽；

【作者基本信息】 南京农业大学 ， 食品科学与工程， 2021， 硕士

【摘要】 紫背天葵（Gynura bicolor DC,G.bicolor）,富含多酚、氨基酸、脂质和矿物质等,是一种兼具营养价值与药用价值的蔬菜。但是采后紫背天葵容易出现感官品质和营养下降的问题,因此适当的采后保鲜技术对紫背天葵而言非常重要。1-MCP处理可有效延缓大多数果蔬的采后品质劣变并延长其保鲜期。1-MCP处理紫背天葵的贮藏保鲜研究主要集中在生理生化层面,在转录层面和代谢物层面的研究较少。本研究使用10μL L^-11-MCP对紫背天葵熏蒸6 h处理,常温贮藏7 d,基于3+2代转录组和广泛靶向组学技术,研究1-MCP处理对采后紫背天葵抗氧化系统和酚类代谢途径的影响,结论如下:（1）基于三代全长转录组测序技术构建采后紫背天葵的参考转录组文库,获得12877条去冗余全长转录本序列,平均长度为2292 bp,共有12276条序列得到注释。二代转录组测序结果表明1-MCP处理后的紫背天葵分别在贮藏期第1、3、7 d获得258个、1157个、344个差异表达基因,KEGG代谢通路富集结果表明1-MCP处理显著调控了苯丙烷合成代谢途径。同时,1-MCP处理对抗氧化系统也有明显的调控作用。（2）利用广泛靶向代谢组学技术在紫背天葵中共检测到570种代谢物,其中黄酮类（117个）和酚酸类（78个）代谢物最多。KEGG代谢通路富集结果表明1-MCP处理导致的42个差异代谢物主要富集在黄酮代谢和苯丙烷合成途径;其中被富集在酚类代谢途径的有8个差异代谢物,分别是橙皮素、柚皮素、山奈酚、肉桂酸、柚皮素查尔酮、阿魏酸、二氢山奈酚和绿原酸。（3）1-MCP处理延缓了采后紫背天葵的感官品质的下降,抑制了呼吸速率和电导率,减少了O₂^·-和H₂O₂的积累,保持了AsA和GSH含量,同时在不同的贮藏时间不同程度地刺激了抗氧化酶相关基因GbSOD、GbAPX1、GbCAT、GbGR的表达量并提高了SOD、APX、CAT和GR的活性。（4）1-MCP处理提高了采后紫背天葵的总酚、总黄酮和总花青素的含量,降低了木质素的含量,并增强了其抗氧化能力。相关性分析表明,1-MCP处理通过上调类黄酮和花青素合成相关基因GbPAL、GbCHS、GbDFR、GbANS、GbUFGT的表达和提高PAL、4CL的酶活性,从而提高了代谢途径中的各种单体酚（肉桂酸,山奈酚,芦丁和绿原酸）的生物合成导致酚类的积累;通过下调木质素合成基因GbC4H、GbCOMT、GbF5H、GbC CoAOMT的表达,降低了阿魏酸和木质素含量;此外,1-MCP处理抑制了PPO和POD活性的上升从而延缓了酚类氧化降解。更多还原

【Abstract】 Gynura bicolor DC（G.bicolor）,rich in polyphenols,amino acids,lipids and minerals,is a vegetable with both nutritional and medical value.Postharvest G.bicolor is prone to the problems of sensory quality and nutritional value decline,so proper storage is very important to prolong its shelf life.Previous studies have shown that 1-MCP treatment could effectively delay the quality deterioration of postharvest G.bicolor and prolong the storage period.These studies mainly focused on physiological and biochemical level about the effects of 1-MCP on postharvest G.bicolor,yet few studies at the transcription and metabolite levels.In the study,G.bicolor was treated by 10μL L^-1 1-methylcyclopropene for 6 h and stored at room temperature for 7 d.Based on full-length transcriptome sequencing,next generation sequencing and widely targeted metabolome,effects of 1-MCP treatment for 6 h on the antioxidant system and phenolic metabolic pathways of G.bicolor were examined,the conclusions are as follows:（1）The full-length transcriptome sequencing of postharvest G.bicolor was carried out to constructed reference transcriptome library.12877 de-redundant full-length transcript sequences with an average length of 2292 bp were obtained,and a total of12276sequences were annotated in data base.Next-generation sequencing results showed that 258,1157,and 344 DEGs respectively was obtained in G.bicolor treaded by 1-MCP on days 1,3,and7.The result of KEGG pathway enrichment showed that 1-MCP treatment significantly regulated phenylpropane biosynthesis.What’s more,the antioxidant system was significantly regulated by 1-MCP treatment.（2）A total of 570 metabolites were detected in G.bicolor using widely targeted metabolome technology.Flavonoids（117）and phenolic acids（78）are the most metabolites.The result of KEGG pathway enrichment showed that the 42 differential metabolites caused by 1-MCP treatment were mainly enriched in flavonoid biosynthesis,phenylpropanoid biosynthesis.Among them,8 differential metabolites including naringenin,naringenin chalcone,kaempferol,dihydrokaempferol,hesperetin,cinnamic acid,ferulic acid and chlorogenic acid,were enriched in phenolic metabolic pathways.（3）1-MCP treatment delayed the decline of the sensory quality of G.bicolor,decreased the respiration intensity and electrolyte leakage,and suppressed the accumulation of O₂^·-and H₂O₂.1-MCP maintained the contents of ascorbic acid and glutathione.Meanwhile,1-MCP stimulated the expression of genes related to antioxidant enzymes（GbSOD,GbAPX1,GbCAT,GbGR,）to varying degrees,and further strengthened the activity of SOD,APX,CAT,and GR in the different storage time.（4）1-MCP treatment increased the content of total phenolics,flavonoids and anthocyanins but decreased that of lignin,leading and the enhancement of antioxidant capacity of G.bicolor.Correlation analysis result showed that 1-MCP increased the contents of cinnamic acid,kaempferol,rutin,and chlorogenic acid by upregulating the expression of gene（GbPAL,GbCHS,GbDFR,GbANS and GbUFGT）related to flavonoid and anthocyanin biosynthesis and improving the activity of PAL and 4CL,leading the accumulation of total phenolics;but reduced the ferulic acid content by downregulating the expression of genes（GbC4H,GbCOMT,GbF5H and GbCCoAOMT）related to lignin biosynthesis.On the other hand,1-MCP inhibited the rise of PPO and POD activity to delay the degradation of phenolics.更多还原