Evaluation and prediction of ecological suitability of medicinal plant American ginseng (panax quinquefolius)

Objective： American ginseng is a medicinal plant with large market demands,however,its producing areas are shrinking because of the continuous cropping obstacles in China.Therefore,it is urgent to establish a suitable model to determine the new producing areas.Here we evaluated and predicted the suitable areas of American ginseng using the maximum entropy model（Max Ent）.Methods： Based on the 37 environmental variables over thirty years from 1970 to 20 0 0 and 226 global distribution points of American ginseng,Max Ent was used to determine the global ecological suitable areas for American ginseng.The Receiver Operating Curve（ROC）was used to evaluate the model prediction accuracy.Meanwhile,an innovative ecological variable,the precipitation–temperature ratio,was established to indicate the climate characteristic in the American ginseng suitable areas based on the monthly precipitation and temperature.Results： The potential ecological suitable areas of American ginseng were primarily in Appalachian Mountain in America and Changbai Mountain in China,about in the range of 35 °N–50 °N,60 °W–120 °W and 35 °N–50 °N,110 °E–145 °E,respectively,including the United States,Canada,China,North Korea,South Korea,Russia and Japan.South Korea and Japan were the potential producing regions.The precipitation–temperature ratios were stable at（0.22,0.56）of the vigorous growth period（April–October）in the best suitable areas of American ginseng,serving as characteristic parameters to optimize the prediction model.The model showed that the common soil parameters were pH 4.5–7.2,Base Saturation（BS）above 80%,Cation Exchange Capacity（CEC）10–20 cmol/kg,organic carbon（OC）〈 1.4%,and the soil types were sandy loam or loam.Conclusion： An optimized Max Ent model was established to predict the producing area for American ginseng that needed to be validated by a field test.

Parasitic relationship of Cistanche deserticola and host-plant Haloxylon ammodendron based on genetic variation of host

Objective: Cistanche deserticola is a famous and endangered medicinal plant that is parasitic upon Haloxylon ammodendron with rather low parasitic rates. It is important to find high affinity germplasms for increasing the survival of C. deserticola. However, little is known in genetic variation and high affinity populations of H. ammodendron in China.Methods: In this study, 98 accessions of H. ammodendron seeds were collected from five regions covering almost the entire natural distribution of H. ammodendron in China. Their genetic variations were analyzed using AFLP and ITS by the maximum parsimony method, and a dendrogram was constructed using the unweighted pair-group method with arithmetic average(UPGMA). The parasitic rates of C. deserticola on different accessions of H. ammodendron were calculated in the field experiment.Results: Both AFLP and ITS methods consistently revealed that there was a high level of genetic diversity in the natural populations of H. ammodendron. Hierarchical population structure analysis uncovered a clear pattern that all populations were grouped into three main clusters, and eight populations from eastern region were genetically clustered together. These regions were significantly differentiated(P < 0.05), 13.10% of variation occurred among populations, and 86.90% within populations was revealed by analysis of molecular variance(AMOVA). The populations of Inner Mongolia had the highest parasitic rates followed by Ganjiahu Reserve and Yongning Plantation for the top three, which were not completely related to the genetic variation.Conclusion: Genetic characteristics of H. ammodendron in China were clarified and the order of affinity of different populations was given, which were primers for discovering high affinity germplasms.