Evaluation of the genetic diversity of Bupleurum using amplified fragment length polymorphism analysis.

Radix bupleuri (Chaihu), the dried root of the Bupleurum plant, is an important component of traditional Chinese medicine. In this study, we examined the genetic diversity of 11 Bupleurum strains, originating from 7 provinces in China, using amplified fragment length polymorphism analysis. A total of 274 polymorphic bands were obtained using 6 primer combinations, indicating a high level of polymorphism across all strains. An estimation of the relative relationships among strains revealed genetic distances ranging from 0.2183 to 0.7372, with an average of 0.4161. The 2 most closely related varieties were Bupleurum chinense DC. strains collected from Lushi, Henan, and Zhangjiakou, Hebei, with a genetic nearness of 0.2183. Hierarchical clustering divided the strains into 3 main groups, with B. falcatum L. from Hebei and Liaoning Provinces forming a cluster that diverged from that of B. smithii Wolff. and B. chinense DC. B. falcatum L. (Sandao chaihu), collected from Heze, Shandong, clustered independently of the other strains, suggesting that this strain may have been introduced from a different location or that it arose as a result of intraspecific variation. B. smithii Wolff. (Hei chaihu) was closely associated with B. scorzonerifolium Willd. (Nan chaihu) and B. chinense DC. (Bei chaihu), suggesting a common genetic origin.

Effect of carotenoid biosynthesis inhibition on the chlorosome organization in Chlorobium phaeobacteroides strain CL1401.

We have studied the effect of the absence of carotenoids on the organization of bacteriochlorophylls (BChls) in chlorosomes of Chlorobium (Chl.) phaeobacteroides strain CL1401. Carotenoid-depleted chlorosomes were obtained by means of 2-hydroxybiphenyl-supplemented cultures. In the presence of the inhibitor, isorenieratene (Isr) and beta-Isr biosynthesis were inhibited to more than 95%, leading to an accumulation of the colorless precursor phytoene inside the chlorosomes. In addition, there was a 30-40% decrease in the baseplate BChl a content. The absorption spectrum of the carotenoid-depleted chlorosomes showed a 10 nm blue shift in the BChl e Qy absorption peak. Under reducing conditions, a decrease in the BChl a/BChl e fluorescence emission ratio was observed in carotenoid-depleted chlorosomes relative to that in control chlorosomes, caused mainly by the decrease in the BChl a content. The steady-state fluorescence emission anisotropy in the BChl e region dropped from approximately 0.24 for native chlorosomes to approximately 0.14 for carotenoid-depleted ones, indicating reorganization of BChl e. The circular dichroism (CD) signal of the carotenoid-depleted chlorosomes was increased two times in the BChl e Qy region. A simple model based on the structure proposed was used to explain the observed effects. Carotenoids might affect the angle between the direction of the BChl e Qy transition and the axis of the rod. The orientation of BChl a in the baseplate remains unchanged in carotenoid-depleted chlorosomes, although there is a partial loss of BChl a as a consequence of a decrease in the baseplate size. The carotenoids are most likely rather close to the BChls and appear to be important for the aggregate structure in Chl. phaeobacteroides.