| Endophytic fungi refers to a kind of fungi whose part or all of its life history parasitic in the plant body,and dose not cause obvious symptoms of disease to its hosts.Schima superba is one of the main timber forest tree species in Southern China collective forest region,and possesses good ecological and economical benefits.As to fertility barren soil in southern area,especially the lack of phosphorus,resulting in decreased production of Schima superba plantation,and the plantation development scale is also limited.Since the 19th century,there are many researches about endophytic fungi can promote plant growth and development,and improve the stress resistance of host plants under stress conditions,but the screening of endophytic fungi from Schima superba and its growth promoting effect has not been reported.Therefore,it is of great significance to study the effect of endophytic fungi on the growth and resistance to low phosphorus stress of Schima superba,and it is also have a significance meaning to improve the yield of Schima superba plantation by using microbial resources.In this paper,the endophytic fungi in leaves,stems and roots of Schima superba were isotaled by tissue separation method,and the dominant fungi,phosphate-solubilizing fungi were be selected from it.In order to develop a mutualism relationship between endophytic fungis and schima superba,five dominant fungi were be inoculated in schima superba seedling under normal growth condition,and four phosphate-solubilizing fungi were be inoculated under four kinds of phosphorus stress conditions(16mg/kg、8mg/kg、4mg/kg、0mg/kg).Finally,the effects of endophytic fungi on the growth and low phosphorus stress resistance of Schima superba were analyzed by measuring the growth,physiological and biochemical indexes.1.To screen Endophytic fungi isolated from Schima superba.A total of 106 strains of endophytic fungi were isolated and identificated from 30 samples of Schima superba.In these endophytic fungi,50 strains were from the leaves,31 strains were from the roots,25 strains were from the stem.Combined with the analysis of NCBI database,the 5 dominant fungi and 4 Phosphate-solubilizing fungi were screened from it,there were MY8(Corynespora sp.),MY21(Colletotrichum sp.),MJ47(Pestalotiopsis sp.),MJ49(Fusarium sp.)And MY57(Arthrinium sp.),MG37(Botryosphaeria sp.),MG42(Penicillium sp.),MY63{Colletotrichum sp.)and MY72(Penicillium sp.).2.Effects of different Endophytic fungi on the growth of Schima superba seedlings.The results showed strains MY8,MY21 and MJ47 had a growth-promoting effect on root-shoot ratio,which increased 62%、90%and 93%to the treatment of uninoculated seedlings,respectively.The aboveground biomass of seedlings inoculated with strains MY21 and MJ47 increased 69%and 48%,respectively.Furthermore,the chlorophyll content,maximum photochemical efficiency(Fv/Fm)and potential photochemical efficiency(Fv/F0)of Schima superba seedlings were increased significantly by inoculated with strains MY21,MJ47 and MJ49.On the nutrient absorption of Schima superba seedlings,① the content of organic C inoculated with strain MJ49 was 50%higher than the treatment of uninoculated seedlings,while the content of aboveground organic C inoculated with strain MY57 was 13%higher than the treatment of uninoculated seedlings.②And compared with the treatment of uninoculated seedlings,the contents of aboveground nitrogen inoculated with strain MY8,MY21,MJ47,MJ49 and MY57 were increased 167%,78%,47%,51%and 56%,respectively.While the contents of underground nitrogen inoculated with strain MY8 and MY57 were increased 34%and 42%.③All the strains could not promote the absorption and utilization of phosphorus elements in Schima superba seedlings.But,the results showed that the aboveground K of seedling inoculated with strains MY8 and MJ47 were significantly increased 22%and 29%to the treatment of uninoculated seedlings.3.Effects of phosphate-solubilizing fungi inoculation on growth and physiological and biochemical characteristics of Schima superba seedlings under low phosphorus stress.The results showed that all strains treatment could significantly promote the growth of height.Moreover,the root collar diameter,biomass and root-shoot ratio inoculated with strain MY72 were significantly higher than the treatment of uninoculated seedlings under mild stress,which were increased 11.5%、65%and 115%,respectively(P<0.05).On the photosynthesis characteristics of Schima superba seedlings,the chlorophyll content of seedlings showed a continuous descend trend with increasing phosphorus stress.And with duration of stress time,the chlorophyll content of seedlings gone up,then went down and gone up last.When stressed to 120 days,all strains treatment could increase the chlorophyll content of seedlings,and the strain MY72 could significantly promote the chlorophyll content of seedlings under four kinds of phosphorus stress.In addition,maximum photochemical efficiency(Fv/Fm)and potential photochemical efficiency(Fv/F0)of seedlings were increased significantly by all fungi treatment under four phosphorus stress conditions.On the nutrient absorption of Schima superba seedlings,① the strains MG37 have a significant impact on the aboveground and underground orgnic C under normal stress condition,which increased 28%and 31%than the treatment of uninoculated seedlings,respectively.And compared with the treatment of uninoculated seedlings,the aboveground and underground orgnic C,aboveground and underground C:N inoculated with strain MY72 were increased 48%,43%,25%and 23%under moderate stress condition,respectively.Furthermore,the strain MY72 have a significant impact on the aboveground and underground nitrogen under severe stress condition,which were increased 48%and 28%,respectively.② The strain MG37 could significantly promote the absorption and utilization of P and K under the severe stress condition.Compared with the treatment of uninoculated seedlings,the aboveground and underground P respectively increased 84%and 51%,and the aboveground and underground K content increased 19%and 30%respectively.On the physiological and biochemical characteristics of Schima superba seedlings.With the increase of phosphorus stress,the SOD activity,MDA content and electrical conductivity of seedlings by all strain treatment showed a upward trend overall,but the content of soluble protein showed a downward trend overall.And with duration of stress time,the content of MDA and relative conductivity were went down first and then gone up,but the activity of SOD and the content of soluble protein were gone up first,then went down and gone up last.Furthermore,under four kinds of phosphorus stress condition,strain MY72 could significantly decrease the content of MDA and relative conductivity,but significantly increased the content of soluble protein and SOD activity.While compared with high concentration of phosphorus condition,the strain MY63 had a better impact on promoting the content of soluble protein under low concentration of phosphorus condition.On the activity of acid phosphatase in leaves,roots of Schima superba seedlings and in rhizosphere soil were as follows:(1)Under four kinds of phosphorus stress conditions,strain MG37 could significantly increase the activities of acid phosphatase in leaves,and the activities of acid phosphatase in roots and rhizosphere soil were significantly risen by inoculated with strain MY72.On the activities of acid phosphatase in root of seedlings,compared with the treatment of uninoculated seedlings,strain MG72 could significantly increase 32%under moderate stress,and strain MG42 could significantly increase 26%under severe stress.Furthermore,strain MY72 had a significantly effect on the activities of acid phosphatase in the rhizosphere soil of the seedlings,which could increase 26%than the treatment of uninoculated seedlings under severe stress. |
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