Studies On The Correlation Between Arbuscular Mycorrhiza And Camptothecin In Camptotheca Acuminata Seedlings

This research was aimed to reveal the dynamic variation of camptothecin content in Camptotheca acuminata seedlings inoculated with three arbuscular mycorrhizal fungi(AMF, Acaulospora mellea,Am;Glomus intraradices,Gi;Glomus diaphanum,Gd) in greenhouse pots,and observe the accumulation of the alkaloid camptothecin(CPT) in the mycorrhizal seedling roots.The correlation between the secondary metabolite CPT and the mycorrhizal C. acuminata seedlings was discussed briefly.The main results were as follows:1.Arbuscular mycorrhiza can influence the CPT content of C.acuminata seedlings, while it was not same in different organs.The CPT content in roots increased very slowly with the seedlings grown.The content in main roots and different lateral roots of arbuscular mycorrhizal seedlings were higher than non-mycorrhizal seedlings,and the difference was more obvious at latter sampling period.The CPT content of roots rose above the ordinary level when the seedlings were just infected by AME The CPT content of stems increased gradually in non-mycorrhizal seedlings,and decreased gradually in mycorrhizal seedlings.The content and variation of CPT in stems were different in three mycorrhizal seedlings.The content and variation of CPT in mycorrhizal seedling leaves were as same as non-mycorrhizal seedlings approximately.It decreased slowly at early period and increased speedily at middle period,and decreased again rapidly when reached a maximum in July 22.Therefore,it was balanced at latter period.The CPT content of whole seedlings between mycorrhizal seedlings and non-mycorrhizal seedlings were not obvious,and the variation was similar to seedling leaves.The CPT yield of mycorrhizal seedlings was higher than non-mycorrhizal seedlings mostly at last sampling period.The CPT yield of the seedlings inoculated with Acaulospora mellea was much higher than other mycorrhizal seedlings.The allocation of CPT in different organs was influenced by AMF,it was increased in leaves and roots,decreased in stems.As a whole,the order of CPT yield in different seedling organs was as follows:leaf＞stem＞root,as the CPT content.2.A method for observing CPT in the roots of mycorrhizal C.acuminata seedlings was established.The CPT autofluorescence was mainly located in the arbuscular mycorrhizal region and the segregator idioblasts(specialised cells which can accumulate alkaloid).There was more CPT autofluorescence in Am than other fungus.The CPT autofluorescence varied at different periods.There were less CPT autofluorescence and intensities at early infection period.The hyphaes of AMF extended and then the arbuscules were formed,the CPT autofluorescence located in the arbuscular mycorrhizal region and its intensity increased correspondingly,but the autofluorescence located in the hyphae region was weak.The CPT of latter sample had accumulated in arbuscules,hyphaes and vesicles,then bright autofluorescence sites were formed,and the autofluorescence located in vesicle shifted from wall to inside.The CPT content of mycorrhizal seedling roots increased with the CPT autofluorescence accumulated correspondingly.This showed that accumulation of CPT increased the CPT content of arbuscular mycorrhizal seedling roots.