Linda Benedict, Liu, Zhijun | 8/6/2009 7:29:16 PM
Researchers look at growth and CPT concentrations in 18 seed sources
Camptotheca acuminata, a deciduous tree native to southern China, contains camptothecin (CPT). In 1996, the FDA approved two CPT derivatives for treating ovarian and colorectal cancer. In addition, other derivatives of CPT are being tested in clinical trials against other types of cancer in the United States. Manufacturing of the two anti-cancer drugs continues to rely on extraction from plant materials harvested mainly from naturally grown trees. There is no known plantation production in an agricultural setting in the United States or in China to supply the plant materials.
The medicinal plant research program at the LSU Agricultural Center initiated a study using Camptotheca acuminata to develop a production system. Cultivation of C. acuminata not only presents cropping opportunities but also allows the input of effective production management that offers superior quality raw materials to the now available natural sources. Since 1993, plantations of C. acuminata have been grown in southern Louisiana, and extensive growth studies have been done to find cultural practices to enhance the levels of CPT. The plantations, however, were established with propagules from a single tree that is perhaps the offspring of an earlier introduction program of the U.S. Department of Agriculture. Therefore, the genetic base is narrow. C. acuminata, however, has a broad range of natural distribution in China, covering almost all areas south of the Yangtze River.
The vast distribution area led the researchers to believe that natural variations in terms of growth and camptothecin concentrations exist. Consequently, cooperative research between the LSU Agricultural Center and Zhejiang Forestry College was conducted to find these variations and to lay the foundation for clonal line development. Once the clonal lines are developed, specific cultivation practices using these clonal lines can be developed for high quality raw plant material production. This provenance study, which means an investigation of variations associated with geographical source of C. acuminata, is the first step in the effort to cultivate C. acuminata in both Louisiana and Zhejiang of China.
Within its natural distribution, 18 seed sources were collected from 10 provinces south of the Yangtze River (Figure 1). Trees 20 to 29 years old bearing seeds were selected from a large local area in November. In Huzhou City, Zhejiang, China, nursery beds were prepared for the study.
Results showed significant variations among the 18 seed sources in growth rate and leaf CPT concentrations. Since leaves are the target plant materials, based on the findings of this study, the top five seed sources were identified. These seed sources warrant further growth studies to determine the optimal growth conditions for accumulating CPT.
Zhijun Liu, Assistant Professor, School of Forestry, Wildlife and Fisheries, LSU Agricultural Center, Baton Rouge, La.; Guomo Zhou, Associate Professor, and Shaoyuan Xu, Professor, both at Zhejiang Forestry College, Lin’an, Zhejiang, People’s Republic of China.
(This article was published in the summer 1999 issue of Louisiana Agriculture.)