【作者】 张雪；

【导师】 蒋欣梅；

【作者基本信息】 东北农业大学 ， 蔬菜学， 2023， 硕士

【摘要】 蒲公英(Taraxacum mongolicum Hand.-Mazz)为菊科多年生草本植物,含有多种活性成分,光照作为植物生长过程中重要的环境调控因子,对蒲公英生长与主要活性成分积累的研究还处于初始阶段。为此,本研究以二年生蒲公英为试验材料,设置了四个遮光处理:20%(T1)、40%(T2)、60%(T3)、80%(T4),并以自然光(不遮光CK)为对照,一部分用于生长过程中不进行采收的取样(即遮光后15、30、45、60、75、90d取样),另一部分用于生长过程中进行采收的取样(即6月20日开始采收第一茬,之后每隔20d采收1茬次,连续采收5茬次,在采收的同时测定相关指标)。通过研究不同遮光率对蒲公英生长及主要活性成分积累的影响,明确初生代谢、次生代谢、光合特性与蒲公英主要活性成分的关系,对蒲公英生产提供参考,为解析蒲公英有效活性成分积累规律提供理论基础。通过试验获得结果如下:(1)遮光对蒲公英叶片形态产生明显的影响,20%-40%的遮光率利于蒲公英叶片生长、地上部生物量积累及光合效率的提高。遮光不利于蒲公英地下部生物量的积累。未进行遮光的对照(CK)蒲公英叶片表现狭窄、叶裂较深,随遮光率的增加,蒲公英叶裂变浅。蒲公英叶片数、叶面积、地上部生物量、根冠比、净光合速率(Pn)、PSII最大光化学效率(Fv/Fm)随着遮光率的增加均表现先升高后降低趋势,在20%或40%遮光率下达到最大值;遮光不利于蒲公英根部的生长,地下部干重随着遮光率的增加呈显著降低趋势。(2)遮光不利于蒲公英总三萜的积累,20%遮光有利于蒲公英总黄酮、总胆碱、木犀草素、芦丁、槲皮素、绿原酸、咖啡酸、菊苣酸的积累,40%遮光更利于叶片中总酚的积累。叶片中的各有效活性成分含量明显高于根部,对于不采收的蒲公英,处理的15-75d总黄酮、总酚、总胆碱、木犀草素、芦丁、槲皮素、绿原酸、咖啡酸、菊苣酸含量均随着遮光率的增加呈先升高后降低趋势,总酚在40%遮光处理下含量最高,其他成分在20%遮光处理下含量最高。在处理90d时,叶片中总黄酮、芦丁、绿原酸含量低于CK,根中槲皮素、木犀草素、总胆碱、总黄酮含量低于CK,差异均不显著。对于采收的蒲公英,前四次采收中,各活性成分含量均随着遮光率的增加呈先升高后降低趋势,在20%或40%遮光达到最大值;随着采收次数的增加,各活性成分含量呈先升高后降低趋势,第二、三次采收时,含量较高。(3)适度遮光有利于提高蒲公英的体外抗氧化活性,总黄酮、总酚、绿原酸、咖啡酸、菊苣酸的积累有利提高DPPH、ABTS~+、OH~-自由基清除能力。DPPH、ABTS~+、OH~-自由基清除能力随着遮光程度的增加呈先升高后降低趋势,20%遮光显著提高了蒲公英DPPH、ABTS~+的自由基清除能力;40%遮光显著提高了蒲公英叶片的OH~-自由基清除能力。结合相关性分析得出,总黄酮、总酚、绿原酸、咖啡酸、菊苣酸的含量与OH~-自由基清除能力呈极显著的正相关关系,总酚含量与ABTS~+自由基清除能力呈极显著正相关关系,各活性成分含量也与DPPH自由基清除能力呈正相关关系。(4)光合效率与蒲公英各活性成分积累呈正相关关系。叶片中,总胆碱含量与净光合速率呈极显著正相关性;总黄酮、芦丁、绿原酸与Fv/Fm呈极显著正相关性;总黄酮、总酚、芦丁、木犀草素、槲皮素、绿原酸、咖啡酸、菊苣酸含量与光化学猝灭系数(q P)呈极显著正相关性,总酚含量与非光化学猝灭系数(NPQ)呈极显著负相关性。根部中总黄酮与Pn、Fv/Fm、PSII实际光化学效率(ΦPSⅡ)呈正相关性。(5)蒲公英有效活性成分的积累受初生代谢和次生代谢过程产物及相关酶活性影响。叶片中可溶性糖、蔗糖、可溶性蛋白、总氨基酸含量较高有利于总酚、咖啡酸、绿原酸、菊苣酸的积累,高水平的苯丙氨酸解氨酶(PAL)、肉桂酸羟化酶(C4H)、4-香豆酸-Co A连接酶(4CL)、查尔酮合成酶(CHS)活性有利于总黄酮、芦丁、绿原酸的积累,以上均达到极显著正相关性。根部中总黄酮、总酚、木犀草素、槲皮素、绿原酸、咖啡酸、菊苣酸含量与GS(谷氨酸合成酶)、NR(硝酸还原酶)、PAL、C4H、4CL酶活性及C4H基因表达量均呈极显著的正相关性。更多还原

【Abstract】 Taraxacum mongolicum Hand.-Mazz is a perennial herb in the Asteraceae family and contains a variety of active ingredients.Light is an important environmental regulator in plant growth,but its effect on the growth and accumulation of the main active ingredients of Taraxacum mongolicum are still infancy.Therefore,in this study,biennial Taraxacum mongolicum was selected as the experimental subject and four shade treatments:20%(T1)、40%(T2)、60%(T3)、80%(T4))and a control group with natural light(CK)were set up,one for sampling without harvesting(15,30,45,60,75 and 90d after shade)and the other for harvesting(the first crop was harvestedd on 20June,followed by one crop every 20d for five consecutive harvests,with relevant indicators measured at the same time).The effect of different shading rates on the growth and accumulation of the main active ingredients of Taraxacum mongolicum was studied to clarify the relationship between primary metabolism,secondary metabolism,photosynthetic properties and the main active ingredients of Taraxacum mongolicum,to provide a reference for Taraxacum mongolicum production and a theoretical basis for the analysis of the accumulation pattern of the effective active ingredients of Taraxacum mongolicum.The following results were obtained from the experiments:(1)Shade significantly changes the morphology of Taraxacum mongolicum leaves.20%-40%shade increases the growth of Taraxacum mongolicum leaves and above-ground biomass accumulation and photosynthetic efficiency,but shade is detrimental to the accumulation of below-ground biomass in Taraxacum mongolicum.The control(CK)Taraxacum mongolicum leaves without shading showed narrower and deeper leaf fractures,which became shallower with increasing shade.The number of Taraxacum mongolicum leaves,leaf area,above-ground biomass,root to crown ratio,net photosynthetic rate(Pn),and maximum photochemical efficiency of PSII(Fv/Fm)tended to increase and then decrease with increasing shade,and reaching a maximum at20%(T1)or 40%shade(T2);shade was detrimental to the growth of Taraxacum mongolicum roots,and its dry weight of the under ground tended to decrease significantly with increasing shade.(2)Shade was not favourable for the accumulation of total triterpenes in Taraxacum mongolicum,while 20%shade was favourable for the accumulation of total flavonoids,total choline,luteolin,rutin,quercetin,chlorogenic acid,caffeic acid and chicory acid in Taraxacum mongolicum,and 40%shade was more favourable for the accumulation of total phenols in the leaves.The content of each active ingredient in the leaves was significantly higher than that in the roots.For the unharvestedd Taraxacum mongolicum,the content of total flavonoids,total phenols,total choline,luteolin,rutin,quercetin,chlorogenic acid,caffeic acid and chicory acid firstly increased and then decreased with increasing shade from 15 d to 75 d.The content of total phenols in the 40%shade treatment was highest among all shade treatment,and other ingredients content in the 20%shade treatment has a highest level.While,the content of total flavonoids,rutin and chlorogenic acid in the leaves was slightly lower than that of CK at 90 d.The content of quercetin,lignan,total choline and total flavonoids in the roots was also slightly lower than that of CK.For harvestedd Taraxacum mongolicum,the content of all active ingredients firstly increased and then decreased with increase of shading rate in the first four harvests,and reaching a maximum content at T1 or T2.The content of each active ingredient showed a first increase and then decrease trend with the number of harvests increased,and the higher value at the second or third harvests.(3)Shading was beneficial in improving the antioxidant activity of Taraxacum mongolicum in vitro.DPPH,ABTS~+and OH~-radical scavenging capacity were positively correlated with the contents of total flavonoids,total phenols,chlorogenic acid,caffeic acid and chicory acid.The scavenging capacity of DPPH,ABTS~+and OH~-radicals tended to increase and then decrease with increasing shading.T1 significantly increased the free radical scavenging capacity of DPPH and ABTS~+;T2 significantly increased the OH~-radical scavenging capacity of leaves.Correlation analysis showed that the OH~-radical scavenging capacity was highly significantly and positively correlated with the content of total flavonoids,total phenols,chlorogenic acid,caffeic acid and chicory acid.ABTS~+radical scavenging capacity was highly significantly and positively correlated with the content of total phenols,and the DPPH radical scavenging capacity was also positively correlated with each active ingredient.(4)Photosynthetic efficiency was positively correlated with the accumulation of each active ingredient in Taraxacum mongolicum.In the leaves,total choline content showed a highly significant positive correlation with net photosynthetic rate.Total flavonoids,rutin,chlorogenic acid,and Fv/Fm showed a highly significant positive correlation;total flavonoids,total phenols,rutin,luteolin,quercetin,chlorogenic acid,caffeic acid,and chicory acid content showed a highly significant positive correlation with photochemical burst coefficient(q P),and total phenol content showed a highly significant negative correlation with non-photochemical burst coefficient(NPQ).Total flavonoids in the roots showed a significant positive correlation with Pn,Fv/Fm,and the actual photochemical efficiency of PSII(ΦPSII).(5)The accumulation of active ingredients in Taraxacum mongolicum was influenced by primary and secondary metabolic related enzyme activities.The higher content of soluble sugars,sucrose,soluble protein and total amino acids in leaves facilitated the accumulation of total phenols,caffeic acid,chlorogenic acid and chicory acid.High levels of phenylalanine demineralase(PAL),cinnamic acid hydroxylase(C4H),4-coumaric acid-Co A ligase(4CL),and chalcone synthase(CHS)activities favoured the accumulation of total flavonoids,rutin,and chlorogenic acid,all of which reached highly significant positive correlations.Total flavonoids,total phenols,luteolin,quercetin,chlorogenic acid,caffeic acid and chicory acid content in the roots showed highly significant positive correlations with GS(glutamate synthase),NR(nitrate reductase),PAL,C4H,4CL enzyme activities and C4H gene expression.更多还原