| "Drumstick-forming" is referred to as the drumstick-like(i.e.,inverted trapezoid)thickening appearance of the top stem segment of Panax Notoginseng(Burk.)F.H.Chen.This appearance is observed in the two or three-year-old P.Notoginseng plant that is planted in Wenshan Prefecture,Yunnan Province.Wenshan Prefecture serves as the genuine traditional product area for Notoginseng Radix et Rhizoma.Previous research has confirmed that this phenomenon characterizes the high saponin content and high yield of P.notoginseng roots.However,it is still unclear how it characterizes the flavonoids in the roots of P.notoginseng.This paper utilizes roots from two-year and three-year-old P.notoginseng plants in Wenshan Prefecture as materials to determine the content of total flavonoids,total flavonol,and total anthocyanins.Furthermore,the taproot transcriptome is sequenced and analyzed.Real-time fluorescent quantitative PCR(q RT-PCR)is employed to detect structural genes and regulator genes with significantly different expression levels in the transcriptome.The main results are as follows:(1)For two-year-old P.notoginseng,the "Drumstick-forming" phenomenon was characterized by the significantly lower total flavonoid content in the taproot,while the total flavonol content was not significantly higher,and the total anthocyanin content was extremely significantly higher.In contrast,the total flavonoid content in lateral roots was significantly higher,the total flavonol content was not significantly lower,and the total anthocyanin content was significantly lower.Additionally,the total flavonoid content in rhizomes was significantly lower,the total flavonol content was not significantly higher,and the total anthocyanin content was significantly higher.For three-year-old P.notoginseng,the "Drumstick-forming" phenomenon was characterized by the significantly lower total flavonoid content in the taproot,while the total flavonol content was not significantly higher,and the total anthocyanin content was significantly lower.In contrast,the total flavonoid content in lateral roots was significantly higher,the total flavonol content was significantly lower,and the total anthocyanin content was extremely significantly higher.Finally,the total flavonoid content in rhizomes was significantly higher,the total flavonol content was not significantly lower,and the total anthocyanin content was extremely significantly lower.(2)32 structural gene and 28 transcription factor genes that could potentially be associated with flavonoids synthesis were identified from the genome of P.notoginseng.From the transcriptome sequencing of the taproot of "Drumstick-forming" eight structural genes(Pn C4H2,Pn4CL2/3,Pn CHI2,Pn ANS/LDOX1/2,and Pn FLS1/2)and two transcription factor genes(MYB-Pno02G004731 and MYB-Pno08G000078)were screened out as significantly differentially expressed.The expression levels of these genes were determined using q RT-PCR,and the results were consistent with the FPKM value trend of the transcriptome."Drumstick-forming" characterized the upregulation of Pn C4H2,Pn4CL2,Pn ANS/LDOX1,Pn FLS1/2,and MYB-Pno02G004731 in the taproots of biennial P.notoginseng,as well as the downregulation of other differentially expressed genes.The taproots of three-year-old P.notoginseng showed upregulation of Pn CHI2 and Pn FLS2,along with downregulation of other differentially expressed genes.The changes in flavonoids content are primarily regulated by Pn ANS2,Pn4CL2/3,MYB-Pno08G000078,MYB-Pno02G004731,and Pn FLS1.To summarize,variations exist in the content of total flavonoids,total flavonols,and total anthocyanins between the "Drumstick-forming" and "non-Drumstick-forming" roots of P.notoginseng.These disparities are closely associated with the expression levels of differentially expressed genes(Pn ANS2,Pn4CL2/3,MYB-Pno08G000078,MYB-Pno02G004731,Pn FLS1).This study reveals the impact of "Drumstick-forming" on flavonoids in P.notoginseng roots,improving the connotation of "Drumstick-forming".Furthermore,it establishes a theoretical foundation for optimizing cultivation management strategies of P.notoginseng by inducing "Drumstick-forming". |
