Corresponding Analysis On Camptothecin Content And Arbuscular Mycorrhiza Formation In Camptotheca Acuminata Seedlings

In this paper, Camptotheca acuminata, a special Chinese tree, is used to experimental materials. C. acuminata seedlings were inoculated with Acaulospora mellea (Am) and Glomus intraradice (Gi), respectively. We observed the corresponding variation of arbuscular mycorrhiza colonization and camptothecin content in C. acuminata seedlings during different co-cultivation time and inoculation time. In addition, we also studied the corresponding variation of arbuscular mycorrhizal colonization and camptothecin content in different levels of roots of C. acuminata seedlings inoculated with Acaulospora mellea (Am) and Glomus diaphanum (Gd), respectively, which was based on our previous study that the dynamic variation of camptothecin content in C. acuminata seedlings inoculated with arbuscular mycorrhizal fungi. Furthermore, distribution of arbuscular, hyphae and camptothecin were observed in tissue and cell level by confocal laser scanning fluorescence microscopy analysis techniques. The main results were as follows.1. Effect of inoculation time on camptothecin content in arbuscular mycorrhizal Camptotheca acuminata seedlingsThe increase of camptothecin accumulation caused by inoculated arbuscular mycorrhizal fungi, and significantly reflected in increase of camptothecin yields (camptothecin.contents multiplied by biomass) in mycorrhizal seedlings. However, the reason of increase was different. The increase of camptothecin yields in mycorrhizal seedlings was mainly credited to the increase of camptothecin contents in seedlings (especially in leaves) inoculated at 20 days of seedlings emergence or to the increase of plant biomass in seedlings inoculated at 60 days of seedlings emergence.It is different that the effect on camptothecin metabolism in arbuscular mycorrhizal C. acuminata seedlings and it mainly reflected in roots. The camptothecin content in Am seedlings was significantly higher than non-mycorrhizal seedlings, but it did not significantly increase in Gi seedlings.2. Effect of co-cultivation time on camptothecin content in arbuscular mycorrhizal Camptotheca acuminata seedlingsThe increasing extent of camptothecin contents and yields of mycorrhizal seedlings was different in different co-cultivation time. With the increase of co-cultivation time, the increasing extent of camptothecin contents and yields increased, yet it did not always increase during the whole co-cultivation time. It did not increase or slightly decreased until co-cultivated 21 or 28 days. This corresponded with the variation of arbuscular mycorrhizal fungi infection, which showed that arbuscular mycorrhizal fungi affected camptothecin accumulation.The camptothecin accumulation of two mycorrhizal seedlings was obviously different, especially in roots. The camptothecin yield in roots, stems and leaves of Am seedlings was higher than Gi seedlings. And the difference increased with the increase of co-cultivation time. 3. Corresponding analysis of arbuscular mycorrhizal C. acuminata seedlings and camptothecin content in rootsWith the increase of days after inoculated arbuscular mycorrhizal fungi, camptothecin contents in mycorrhizal seedlings increased, yet the increasing extent was different. With the increase of days after inoculated arbuscular mycorrhizal fungi, the camptothecin contents in main roots and secondary roots increased but they did not increase until 17 days or 42 days after inoculated arbuscular mycorrhizal fungi. However, they in tertiary roots and fourth roots increased during the whole cultivation. It showed that arbuscular mycorrhiza did not improve the accumulation of camptothecin in all roots, but mainly improved in tertiary roots and fourth roots. However, the camptothecin contents in tertiary roots and fourth roots were still lower than that in main roots in the same time. This indicated that main roots were likely the place where camptothecin was synthesized then it was transported to other roots.Variation of camptothecin content was reverse to colonization rate and mycorrhizal colonization intensity of roots in different roots of C. acuminata seedlings in the same time, that is, colonization rate and mycorrhizal colonization intensity of roots in different roots increased but camptothecin contents decreased.4. Corresponding analysis on distribution of arbuscular and camptothecinThere was autofluroescence of camptothecin not only in bundle, epidermis, root tip and root hair, but also in the arbuscular mycorrhizal area (hypha, arbuscular and vesicle) when arbuscular mycorrhiza formed.After arbuscular formed, autofluroescence distributionof camptothecin expanded with the increase of arbuscular. In cells, the larger proportion of arbuscular was, the more distribution of camptothecin autofluroescence was. There is some corresponding relation between them.There was no obvious difference in the two mycorrhizal seedlings.