College of Life Sciences, Zijingang Campus, Zhejiang University, No. 358 Zijinghua Road, Hangzhou 310058, China.
J Chem Ecol. 2010 Mar;36(3):329-38. doi: 10.1007/s10886-010-9760-z. Epub 2010 Feb 21.
Experiments were conducted to determine whether allelochemicals released by the important medicinal plant Scutellaria baicalensis Georgi help to explain why S. baicalensis performs poorly when continuously cropped. Based on high performance liquid chromatography, the concentration of baicalin (the major compound released by S. baicalensis roots) in the soil where S. baicalensi had been grown for 3 years was 0.97 microg x g(-1). Both the crude extracts from S. baicalensis roots and purified baicalin at 0.97 microg x g(-1) increased the mortality of S. baicalensis seedlings in an autotoxicity test. This concentration stimulated the growth of two soilborne pathogens (Pythium ultimum and Rhizoctonia solani) on agar, and their growth and pathogenic activity in sand. Seedling mortality and damping-off caused by both pathogens were greater in sand where S. canadensis had previously grown than in sand where it had not previously grown. Mortality and damping-off of S. baicalensis seedlings also were significantly higher in soil collected from an S. baicalensis field than in soil collected from a Nicotiana tabacum L. field. The results are consistent with the hypothesis that allelochemicals released by S. baicalensis negatively affect S. baicalensis directly by inducing autotoxicity and indirectly by increasing pathogen activity in the soil.
实验旨在确定重要药用植物黄芩释放的化感物质是否有助于解释为什么黄芩在连续种植后表现不佳。基于高效液相色谱法，在黄芩连续种植 3 年的土壤中，黄芩苷（黄芩根系释放的主要化合物）的浓度为 0.97 微克/克。黄芩根的粗提物和 0.97 微克/克的纯化黄芩苷均在自毒试验中增加了黄芩幼苗的死亡率。该浓度刺激了两种土传病原菌（终极腐霉和立枯丝核菌）在琼脂和沙中的生长，以及它们在沙中的生长和致病活性。在先前种植过黄芩的沙中，由两种病原菌引起的幼苗死亡率和猝倒病比在先前未种植黄芩的沙中更为严重。在从黄芩田间采集的土壤中，黄芩幼苗的死亡率和猝倒病也明显高于从烟草田间采集的土壤。这些结果与化感物质由黄芩释放，通过诱导自毒性直接对黄芩产生负面影响，以及通过增加土壤中病原菌活性间接对黄芩产生负面影响的假设一致。
