【作者】 李呈帅；

【导师】 张丽静； 张坤鹏；

【作者基本信息】 兰州大学 ， 农业·农业管理（专业学位）， 2021， 硕士

【摘要】 白沙蒿是我国西北荒漠半荒漠地区重要的先锋物种,具有重要的生态价值和经济价值。白沙蒿种子富含粘液、不饱和脂肪酸--亚油酸以及包括黄酮类化合物等的抗氧化物质,这些物质在种子老化过程中的作用机制值得研究。本研究利用人工老化处理白沙蒿完整和去粘液种子,检测老化过程中种子发芽率、活力、线粒体SOD酶活性和黄酮含量等变化的影响,研究其抗老化机制;并以7个不同发育阶段种子为材料,测定总黄酮含量及其组分,同时利用全长转录组测序鉴定参与黄酮类化合物代谢的相关基因,结合RNA-seq短读测序分析其表达水平,以揭示种子发育过程中黄酮类化合物积累的模式及其调控机制。主要结果如下:(1)随老化时间延长,完整种子和去粘液种子发芽率、活力和线粒体SOD酶活性均呈下降趋势,各指标去粘液种子均低于完整种子,表明去粘液种子更易老化失活。去粘液种子总黄酮含量下降幅度、线粒体总黄酮含量占种子总黄酮含量比例、线粒体的编码黄酮转运蛋白的GST基因表达量程度均高于完整种子,去粘液种子因老化程度更高故需要转运和消耗更多黄酮类化合物以抵御老化。(2)白沙蒿成熟种子中总黄酮含量为15.05 mg/g,包括黄酮醇、查尔酮、黄酮、黄烷酮和花青素共5个亚类,其中黄酮醇占比最大为45.78%。花后40-70天为黄酮快速积累期。(3)白沙蒿黄酮代谢受到结构基因和转录因子共同调控:PAL、4CL和UF3GT高表达促进总黄酮积累;F3’H和FLS高表达使黄酮醇成为主要组分。MBW复合体和SBP转录因子直接调控黄酮代谢结构基因,C2H2、GATA、DREB、GTE、Trihelix和PIF转录因子通过BR和ABA等激素间接促进黄酮类化合物合成。本研究揭示了种子老化过程中粘液和黄酮类化合物的延缓老化作用及发育过程中黄酮类化合物分子合成的调节机制。对荒漠灌木白沙蒿种子的生产及储存具有一定理论及实际应用意义。更多还原

【Abstract】 Artemisia sphaerocephala Krasch.is an important pioneer species in the desert and semi-desert region of northwest China,which has important ecological and economic value.A.sphaerocephala seeds are rich in mucus,unsaturated fatty acids,linoleic acid and antioxidants including flavonoids.The mechanism of these substances in the process of seed aging is worth studying.In this study,artificial aging was used to mucus-removed and intact seeds of A.sphaerocephala,to detect the effects of seed germination percentage,vigor,mitochondrial SOD enzyme activity and flavonoid content during aging,and to study its anti-aging mechanism.The contents and components of total flavonoids in seeds of 7 different developmental stages were determined,and the related genes involved in flavonoid metabolism were identified by full-length transcriptome sequencing,and their expression levels were analyzed by RNA-seq short-reading sequencing,in order to reveal the pattern of flavonoid accumulation and its regulatory mechanism during seed development.The main results are as follows:(1)With the aging time prolonged,the germination rate,activity and mitochondrial SOD activity of intact seeds and mucus-removed seeds showed a downward trend,and the indicators of mucus-removed seeds were lower than those of intact seeds,indicating that mucus-removed seeds were more susceptible to aging and inactivation.The decreasing extent of total flavonoids content,the ratio of total flavonoids content of mitochondria to total flavonoids content of seeds and the expression of GST gene encoding flavonoid transporter in mitochondria were higher than those of intact seeds.Because of the higher degree of aging,demucilized seeds need to transport and consume more flavonoids to resist aging.(2)The content of total flavonoids in mature seeds of A.sphaerocephala Krasch.was 15.05 mg/g,including flavonols,chalcones,flavones,flavanones and anthocyanin,of which flavonols accounted for the largest proportion of 45.78%.The period of rapid accumulation of flavonoids is 40-70 days after anthesis.(3)Flavonoids metabolism of A.sphaerocephala Krasch.is regulated by structural genes and transcription factors: the high expression of PAL,4CL and UF3 GT promotes the accumulation of total flavonoids,and the high expression of F3’H and FLS makes flavonol become the main component.MBW complex and SBP transcription factors directly regulate the metabolic structure genes of flavonoids.C2H2,GATA,DREB,GTE,Trihelix and PIF transcription factors indirectly promote the synthesis of flavonoids through hormones such as BR and ABA.This study revealed the anti-aging effect of mucus and flavonoids during seed aging and the regulatory mechanism of flavonoid molecular synthesis during development.It has certain theoretical and practical significance for the production and storage of desert shrub A.sphaerocephala seeds.更多还原