Study On The Metabolism And Influence Mechanism Of Flavonoids In The Seeds Of Artemisia Sphaerocephala Krasch.

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.