中文摘要：

喜树（Camptotheca acuminata）是我国特有的多年生亚热带落叶阔叶树种,因其次生代谢产物喜树碱具有良好的抗肿瘤活性而受到人们的广泛关注。通过温室盆栽接种试验,观察了喜树幼苗不同生长时期接种蜜色无梗囊霉（Acaulospora mellea）和根内球囊霉（Glomus intraradices）对喜树幼苗喜树碱积累的影响。结果表明接种两种丛枝菌根真菌均促进了喜树幼苗喜树碱的积累,表现为喜树碱产量（单株幼苗所含的喜树碱量,喜树碱含量与幼苗生物量的乘积）的显著提高。进一步分析发现,接种丛枝菌根真菌导致幼喜树苗喜树碱产量的提高,早期（幼苗出土20天）接种主要是源于喜树碱含量的提高,特别是叶片喜树碱含量的提高,而晚期（幼苗出土60天）接种则主要是源于幼苗生物量的增加。

英文摘要：

Aims Arbuscular mycorrhizal fungi can directly or indirectly affect plant secondary metabolic processes. Camptothecin,a secondary metabolite in a special Chinese tree Camptotheca acuminata,has gained great attention for its remarkable inhibitory activity against tumor cells. The effect of two arbuscular mycorrhizal fungi belonging to two genera on the accumulation of camptothecin at different growth times of C. acuminata seedling was carried out in the present study. Methods The selected sterile seeds of C. acuminata were sown in sterilized matrix （a mixture of soil and sand） in the greenhouse. Seedlings with similar height and crown were selected and divided into three groups （30 pots per group）. Each group of C. acuminata seedlings was inoculated with a species of arbuscular mycorrhizal fungi Acaulospora mellea or Glomus intraradices,or non-mycorrhizal inoculation when seedlings unearthed 20 days,40 days and 60 days,respectively. After 30 days of treatment,camptothecin contents and yields in the seedlings of C. acuminata were determined. Important findings All inoculated seedlings were infected by arbuscular mycorrhizal fungi and formed arbuscular mycorrhiza after 30 days of co-cultivation. The results showed that camptothecin yields （camptothecin contents multiplied by biomass） in mycorrhizal seedlings were significantly higher than non-mycorrhizal seedlings. Furthermore,the increase of camptothecin yields in mycorrhizal seedlings was mainly credited to the increase of camptothecin contents in seedlings （especially in leaves） inoculated at early stage （20 days of seedlings emergence） or to the increase of plant biomass in seedlings inoculated at late stage （60 days of seedlings emergence）.