Study On Microscopic Anatomy Of Abnormal Structure In Root Tuber And Accumulation Of Isoflavonoids Of Pueraria Lobata

[Objective](1) To clarify the composition of root system, the development of root tuber and the root tuber traits and the relationship between character and abnormal structure of Pueraria lobata.(2) Based on the qualitative distribution and content determination of isoflavonoids in Puerariae lobata Radix, to explain the relationship between the accumulation of secondary metabolites and the abnormal structure in the root tissues.(3) To discuss the relationship between the accumulation of secondary metabolites distribution and diameters in the root tuber of Pueraria lobata.(4) To clarify the relationship between the longitudinal and the accumulation of isoflavonoids in the root tuber of Pueraria lobata. [Methods]The compositions of the root system were studied by using field investigation of Pueraria lobata. For the study of the abnormal structure in root tuber, developmental anatomy method was used to elucidate the relationship between root tuber traits and abnormal structure. By histochemical localization method, qualitative research was taken on the flavonoids in Puerariae lobata Radix. And HPLC method was used for determining the contents of isoflavonoids in different parts and different diameters of Puerariae lobata Radix. [Results] The results of analysis showed that the root system of Pueraria lobata was developed from seed and adventitious root and it was devided into root tuber, adventitious root and conductive root according to the morphology and function; the root tuber was developed from adventitious root, its secondary structure conformed to that of dicotyledon's root. With the development of root, the secondary phloem of root tuber appeared abnormal vascular tissue, which was distributed like ring in the outside of secondary vascular tissue; and root tuber could have 4-6 concentric circular permutation abnormal vascular tissues. The root tuber was formed by the internal development of abnormal vascular tissue of Pueraria lobata, and the xylem and phloem of abnormal vascular tissue were the main body of the root tuber.Based on the histochemical localization and content determination of flavonoids in the root tuber of Pueraria lobata, the content of flavonoids was different in each tissue. The isoflavonoids mainly distributed in phloem and xylem, the periderm had the minimum content, and phloem had higher content than xylem. The content of isoflavonoids in abnormal vascular tissue near the periderm was higher than other vascular tissue.Isoflavonoids in root tuber of Pueraria lobata with different diameters were determined, and the results showed as follows. The content of root tubers with less than 5 cm diameter was lowering than that with greater than 5 cm diameter. In the root tubers that had greater than 5 cm diameter, the content of isoflavonoids had no significant relationship with diameters, and it showed irregular increase and decrease with the diameters increased.Based on the content determination of isoflavonoids in longitudinal section, the content in the lateral section was higher than that in the medial section. [Conclusion] The root tuber of Pueraria lobata was formed by the internal development of abnormal vascular tissue. The distribution and accumulation of isoflavonoids in different tissues is closely related to the organizational structure of the root. And the distribution and accumulation of isoflavonoids in longitudinal section is also closely related to the organizational structure of the root. Pueraria lobata root tuber of less than 5 cm in diameter has no medicinal value; the diameter and the content of isoflavonoids have no significant correlation in the root tuber of diameter greater than 5 cm. The results reveal the abnormal anatomical structure development of Pueraria lobata also provides the theoretical basis for reasonable harvest medicinal parts and promoting sustainable utilization of resources of Pueraria lobata.