Effects Of Endophytic Fungi On Plant Growth And Metabolism Of Salvia Miltiorrhiza Bge.(Labiatae)

The root and rhizome of Salvia miltiorrhiza Bge.(red sage,family Labiatae),is known as “danshen” in Chinese.Problems like diseases and continuous cropping obstacles become more and more serious in the process of cultivation,which poses a great threat to the safety of production and quality as well as yield of Salvia miltiorrhiza Bge.Researches suggest that endophytic fungi have plant-growth promoting effects,they can also improve the ability to resist stresses,enhance the synthesis secondary metabolites of their hosts,they also have biological control effects.Endophytic fungi are abundant in Salvia miltiorrhiza Bge.,however,their relationship with the host plant lacks a systematic analysis.In this research,we firstly co-cultivated enduphytic fungi with the plantlets of Salvia miltiorrhiza Bge.to find out those that did not harm the hosts.Then a set of growth parameters including plant biomass,cholophyll content,activity of SOD,CAT,POD,MDA content and enzymes of nitrogen and carbon metabolism were selected to compare the difference between S.miltiorrhiza which root were inoculated or non-inoculated with endophytic fungi in order to screen out the plant-growth-promoting fungi;Secondly we did pot experiments to investigate effects of endophytic fungi on the growth of Salvia miltiorrhiza Bge.and the content of active ingredients.For this purpose,we measured the photosynthesis index,enzymes activity of nitrogen and carbon metabolism,antioxidant enzymes activity as well as the yield of seedlings and the content of 8kinds of active ingredients of the host.The main results are as follows:(1)Endophytic fungi affected the biomass of plants,the effects were different.We selected 9 strains of endophytic fungi which could be co-cultivated with the plantlets normally,they were strains of DS5,DS7,DS8,DS10,DS12,DS13,DS16,DS17 and DS18.8 out of 9 strains could improve the biomass of plantlets,In pot experiment,inoculation with 9 strains was capable of increasing the weight of aerial parts,7strains could improve the fresh and dry weight of underground part while comparing with the control.7 strains were able to enhance the fresh weight of medicinal parts while all of 8 strains had a positive impact on the dry weight of medicinal parts of the hosts.Photosynthesis enhanced while infecting by 9 strains of endophytic fungi comparing with the non-inoculated seedlings.6 strains could raise the chlorophyll content.(2)Endophytic fungi had influence in growth of plants by intervening the nitrogen and carbon metabolism.inoculation with all 9 strains could all enhance the photosynthetic capacity,9 strains could all improve the activity of enzymes and products of nitrogen and carbon metabolism.Infection with DS7 had strongest improvement of sucrose synthetase,DS16 showed strongest improvement of sucrose phosphate synthase,DS17 had strongest effect on content of soluble sugar in leaves and reductive sugar in roots while DS18 showed most significant effect on reductive sugar in leaves,DS5 was most beneficial of soluble sugar in roots.As for nitrogen metabolism,inoculation of all strains showed improvement of activity of enzymes,including nitrate reductase,glutamate synthetase and glutamine synthetase as well as content of soluble protein.DS18 showed strongest effect on nitrate reductase,DS13 had strongest effect on glutamate synthetase and soluble protein,while DS10 showed strongest on activity of glutamine synthetase.(3)Endophytic fungi affected the activity of resistance enzymes to improve stress resistance of plants.In the tissue culture experiment,5 strains could improve the activity of antioxidant enzymes,including superoxide dismutase,peroxidase and catalase,9 strains were capacity of decrease the content of MDA,3 strains could increase the activity of phenylalanine ammonialyase.In the pot experiment,DS13 had strongest effect on activity of SOD and CAT,DS18 showed strongest effect on activity of POD,DS5 could enhance the content of proline extremely,DS16 had strongest effect on content of MDA,DS13 showed strongest effect on activity of PAL.(4)Endophytic fungi affected the content and constitution of the active ingredients of plants,the effects were different.In sum,infection with endophytic fungi had a stronger influence on content of tanshinones than content of salvianolic acid.Inoculation with DS5 had a strongest impact on content and biomass accumulation of salvianolic acid while DS12 had a strongest influence on tanshinones content and biomass accumulation.Inoculation with DS5 added mole ratio of salvianolic acid and tanshinones while infection with other 8 strains all decreased the ratio.When involved the salvianolic acid,infection with DS12 could largely change the ratio of molar contnet of caffeic acid and rosemary acid,salvianolic acid B and rosemary acid as well as salvianolic acid A and rosemary acid.As for tanshinones,inoculation with DS16 had a strongest influence on mole ratio of dihydrotanshinone and tanshinone I as well as mole ratio of cryptotanshinone and tanshinone I while DS17 showed a strongest impact on the mole ratio of tanshinone ?A and tanshinone I.Results suggested that endophytic fungi made effect on content of active ingredient and its constituent.In conclusion,inoculation with endophytic fungi can affect the biomass,the carbon and nitrogen metabolism,the antioxidant enzymes and PAL activity of salvia miltiorrhiza,affect the content and composition of active ingredients of Salvia miltiorrhiza.This provides experimental basis for exploring the mechanism of endophytic fungi on the yield and quality of Salvia miltiorrhiza.