| Coastal saline land is widely distributed along the coast of Yellow Sea in China.Because of high soil salt content and poor soil properties,plants can’t survive in this area.Pinus thunbergii,a species with strong salt and drought tolerance and sand fixation to adapt to the malnutrition environment,is suitable for the ecological construction.Pinus thunbergii has a strict mycorrhizal dependence.Mycorrhized plants are generally more tolerant to salt than non-mycorrhizal plants.Therefore,it is of great significance to explore the diversity and community structure of ectomycorrhizal fungi and the mechanism by which ectomycorrhizal fungi improve salt tolerance of host plants for the establishment of coastal pine forest.Based on a field survey of Pinus thunbergii forests along the Yellow Sea coast of China,this study described the characteristics of ectomycorrhizal fungi community in mature pine forests,identified the soil factors driving the fungal community,and preliminarily explored the salt tolerance of ectomycorrhizal fungi from different habitats and the mechanism of improving the salt tolerance of Pinus thunbergia.The result are as follows:1,A total of 74 soil samples were collected from three sites and 53 ectomycorrhizal fungi were identified.Thelephoraceae and Russulaceae are the dominant families,containing12 species and 8 species,respectively.The results showed that Russula sp.1 was the most abundant,accounting for 15.3% of the identified ectomycorrhizal fungi.Most of the remaining species were very rare.At a small scale,host identification had no significant effect on the community composition of ectomycorrhizal fungi(A=0.036,p =0.258),whereas the sampling site did(A=0.135,p =0.041).The results of redundancy analysis(RDA)showed that the contents of Na,K and soil pH had significant effects on the ectomycorrhizal fungi community.Most species preferred to appear in the soil with low Nacontent and low pH.Only Cenococcum sp.1,Tomentella sp.2,Thelephoraceae sp.6 and Cortinarius sp.preferred high Nacontent and high pH soil environment.2,NaCl tolerance experiments ware conducted on Cenococcum geophilum(Cg),Pisolithus sp(P.sp)and Laccaria amethystea(La).Both Cg and P.sp had high tolerance to salt.The growth of them was not affected by 200 m M NaCl,and they maintained growth activity under 300 m M NaCl.Cg kept cell Nacontent in a low level.P.sp stored Nain vacuoles under salt stress.Both Cg and P.sp could maintain the balance of elements in cell and Increase absorption of K under salt stress,whereas La did not have these abilities.3,The potential of Cg,La and P.sp to improve salt tolerance of Pinus thunbergii was evaluated in a 3-month pot experiment.The results showed that the inoculation of ectomycorrhizal fungi could increase the relative growth rate and water content of Pinus thunbergii in saline soil,enhance the T-AOC level and SOD activity of Pinus thunbergii,decrease the content of MDA in different parts,and increase the activities of phosphatase and urease in soil.Compared with Cg and non-mycorrhizal seedlings,P.sp and La could limit the transport of Nato needles,promote the uptake of K by roots,and increase the K/Navalue in different parts of Pinus thunbergii.P.sp also increased chlorophyll content in needles.Inoculation of ectomycorrhizal fungi could enhance the salt tolerance of Pinus thunbergii,but it varies with species(P.sp> La> Cg).When using mycorrhizal technology to restore vegetation in coastal saline land,it is necessary to select the appropriate species according to the influence on the salt tolerance of host plants. |
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