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In the present study the influences of different arbuscular mycorrhizal(AM) fungal species on the formation of water-stable soil aggregates and growth of Medicago sativa L.were examined under simulated drought stresses in a compartmented cultivation system.In addition to observations on mycorrhizal colonization,plant growth responses and soil aggregates,we also monitored soil chemo-physical properties and plant physiological responses for uncovering the mechanisms underlying mycorrhizal functions.The experimental results indicated that,root colonization by Glomus intraradices was significantly higher than those by the other two fungal species,Acaulospora scrobiculata and Diversispora spurcum irrespective to soil water conditions.Under well watered conditions,all three AM fungal species significantly increased plant biomass and P concentrations;while drought stresses significantly inhibited plant growth and mycorrhizal colonization.There were no observable mycorrhizal effects on plant growth under drought stresses,meanwhile,inoculation with D.spurcum even reduced plant biomes,and only G.intraradices increased plant P concentrations.As for mycorrhizal effects on soil structure,AM fungi mainly affected water stable soil aggregates with particle size 2 mm,and G.intraradices exhibited most prominent effects.Consistently,G.intraradices significantly increased the contents of glomalin-related soil proteins in the hyphal compartment of the cultivation system.The study clearly demonstrated the positive influences of AM fungi on formation of large soil aggregates and plant drought tolerance,while there was large variation among different AM fungal species.To make sure of successful ecological restoration of degraded ecosystem with assistance of mycorrhizal fungi,selection of tolerant AM fungal strains should be fully considered.At present,further study is still necessary to reveal the biological and molecular basis for the differences in stress tolerance of different AM fungal species.

Arbuscular mycorrhizal(AM) symbiosis,a ubiquitous symbiotic association established between AM fungi and roots of higher plants in most terrestrial ecosystems,is essentially important for plant adaptation to various environmental stresses,such as nutrient deficiency,environmental pollution and drought,etc.Many studies proved the positive influences of AM on plant drought tolerance and made efforts to uncover the underlying mechanisms: for plant individuals,AM fungi could stimulate plant physiological responses to drought stress;at the ecosystem level,AM fungi could interact with host plant to adapt to an adverse environment.However,systematic study is still necessary to reveal the fundamental role of AM fungi in improving plant drought tolerance. In this mini-review we summarized recent research progresses in the involvements of AM fungi in regulation of plant drought tolerance related genes,such as LEA encoding late embryogenesis-abundant proteins,P5CS encoding △1-pyrroline-5-carboxylate synthetase,MIPs encoding major intrinsic proteins,and NCED encoding 9-cis-epoxycarotenoid dioxygenase.As seen in reports,AM fungi could up-or down-regulate these genes under drought stresses,however,there were conflicting results as for the mycorrhizal effects on gene expressions in different experiments.In most cases,this could be attributed to incomparable experimental conditions,considering that 1) not all members in a gene family had been examined in each experiment;2) different symbiotic associations(plant-AM fungus combinations) might exert different strategies to resist drought stresses,and each fungal species/strain might exhibit different capacity to assist host plant against environmental adversities;3) gene expression varies in different plant tissues at different plant developmental stages.Obviously,it is still necessary to carry out further research for a better understanding of AM regulation of drought tolerance related genes in host plants,and model plants and AM fungal strains might be ideal choices to make sure of comparable results from different experiments. In addition to a full discussion on the insufficiency of previous studies,we also introduced the advances of proteomics in AM physiology and proposed perspectives for future research by the end of this review.

The interaction between exotic invasive plants and soil animal communities is an important aspect of understanding plant invasibility and susceptibility of receptive communities.Consequently,studies on the effects of plant invasion on soil animal communities and their physicochemical properties are becoming increasingly important in determining the effects of plant invasion on ecosystems and the relationship of the invasion mechanism to the underground soil biota.In this paper,we report the soil animal community structure and the soil physicochemical properties of three sampling areas in Jinhua,Zhejiang Province of Eastern China where Solidago canadensis has invaded native plant communities.The objectives of the study are to evaluate how S.canadensis invasion affects the physicochemical characteristics of the plant rhizosphere and the soil animal parameters and to determine whether these parameters can serve as indicators for the invasion density of S.canadensis.Soil samples were collected at three depths over four seasons in different S.canadensis-invaded areas.A total of 9900 individual soil animals,which belong to 14 orders,11 classes,and 3 phyla,were collected.The most dominant taxa in three invaded areas were Collembola and Acarina.Statistical analysis was performed with the SPSS 18.0 program package.The one-way ANOVA shows that pH,organic carbon,ammonium nitrogen,available K,and available P are significantly different among the sampling areas(p 0.05),whereas soil water content and soil temperature were not(p 0.05).The sequence of the diversity indices and the evenness indices were as follows: newly invaded areas moderately invaded areas heavily invaded areas.A positive association was found between diversity index and dominance index.The spatial distribution of soil animals in the different S.canadensis invaded areas had obvious surface segregation.Using the non-metric multidimensional scaling method,the soil animals communities were classified into three types.Grey relevant analysis indicated that the soil physicochemical properties had different effects on the key soil animal communities,Ammonium nitrogen produced the most significant effect on soil animals,followed by organic carbon,available P,and finally by soil water content.Therefore,S.canadensis L.invasion changes the soil physicochemical properties(especially the NH4-N),and then changes the soil animal community used by S.canadensis to expand its invasive range rapidly.

Compared with common organic-inorganic materials,side chain bonded organic-inorganic material has better thermo-stability,and can avoid crystallization and phase separation.And the relaxation of ordered polarized chromophore is restricted as the movement of chromophore is blocked.A kind of stable,good-performance side chain bonded organic-inorganic material was compounded and applied as the electro-optic layer.Conventional semiconductor processing was applied to fabricate strip-loaded waveguide structure and the Mach-Zehnder(M-Z) electro-optic modulators were made.Response signal of 10 kHz was observed at 1 550 nm light source.

The carrier density mobility in organic electron transporting semiconductor is very low compared with the inorganic semiconductor,which affects the efficiency and luminance of Organic Light-emitting Devices(OLEDs).To improve the performance of OLED,the electron injecting and transporting ability should be enhanced,and n-type electrically doping can enhance the electron transporting ability of the orangic materials.Li3N was used as n-type dopant and Alq3∶Li3N doped layer was used as the electron injecting layer for OLED.As a result,the performance of OLED were improved.The optimal doping concentration and the thickness were 5% and 10 nm,respectively.Because Li3N is stable in the air and can decomposite to Li atoms and nitrogen at a low temperature and pressure,the disadvantage can be avoided of the effecting of moisture and oxygen to the metal dopant such as Li and Cs.The research result is also helpful to the preserve and doping process.

A tunable photonic crystal filter is proposedwith parallel nematic liquid crystal as defect layer. The transmission modes while varying incident angle are discussed in detail by 4 4 matrix method. The results show that transmission modes are mainly decided by the voltage when the incident angle is smaller than 10 . In this region, the transmission modes can be tuned by voltage and different modes can be selected basedon polarization sensitive performance. When the incident angle is greater than 10 , the peaks of two modes shift toward the shorter wavelength side and the change of two modes is different. So the transmission modes can be tunedandselected by varying the incident angle in the voltage region of more than 8 V. Both the tunable range and the flexibility of application are enlarged.