A comprehensive analysis of the response of the fungal community structure to long-term continuous cropping in three typical upland crops

Certain agricultural management practices are known to affect the soil microbial community structure;however,knowledge of the response of the fungal community structure to the long-term continuous cropping and rotation of soybean,maize and wheat in the same agroecosystem is limited.We assessed the fungal abundance,composition and diversity among soybean rotation,maize rotation and wheat rotation systems and among long-term continuous cropping systems of soybean,maize and wheat as the effect of crop types on fungal community structure.We compared these fungal parameters of same crop between long-term crop rotation and continuous cropping systems as the effect of cropping systems on fungal community structure.The fungal abundance and composition were measured by quantitative real-time PCR and Illumina MiSeq sequencing.The results revealed that long-term continuous soybean cropping increased the soil fungal abundance compared with soybean rotation,and the fungal abundance was decreased in long-term continuous maize cropping compared with maize rotation.The long-term continuous soybean cropping also exhibited increased soil fungal diversity.The variation in the fungal community structure among the three crops was greater than that between long-term continuous cropping and rotation cropping.Mortierella,Guehomyces and Alternaria were the most important contributors to the dissimilarity of the fungal communities between the continuous cropping and rotation cropping of soybean,maize and wheat.There were 11 potential pathogen and 11 potential biocontrol fungi identified,and the relative abundance of most of the potential pathogenic fungi increased during the long-term continuous cropping of all three crops.The relative abundance of most biocontrol fungi increased in long-term continuous soybean cropping but decreased in long-term continuous maize and wheat cropping.Our results indicate that the response of the soil fungal community structure to long-term continuous cropping varies based upon crop types.

Contrasting soil fungal communities at different habitats in a revegetated copper mine wasteland

Little is known about the responses of soil fungal communities to revegetation of mine wastelands,representing a major gap in the knowledge needed to improve the performances of revegetation schemes for mine wastelands.To shed some light on this matter,we reestablished 4000 m^(2) of vegetation on an extremely acidic(pH 2.5)copper mine tailings pond and collected soil samples from three different types of habitats:amended layer of the reclaimed tailings(ALRT),unamended layer of the reclaimed tailings(ULRT),and unreclaimed tailings(UT).Soil fungal communities in the 120 samples collected in two consecutive years were characterized via high-throughput sequencing.The fungal diversities at ALRTand ULRT were found to be significantly higher than those at UT.Ascomycota whose relative abundance ranged from 74.5% to 98.4% was the most predominant phylum across all habitats,exhibiting the lowest predominance at ALRT.Two acidophilic fungal genera,Acidomyces and Acidiella,dominated UT with relative abundances being as high as 37.8% and 15.2%,respectively.In contrast,three genera with plant growth-promoting species(Talaromyces,Trichoderma and Penicillium)were abundant at ULRT and ALRT.Remarkably,their relative abundances at ULRTcould be up to 29.0%,26.9% and 9.7%,respectively.The three types of habitats differed considerably in the overall soil fungal community composition at species level,which became more pronounced as time progressed.The abovementioned differences between habitats in soil fungal community features were related to the reduced availability of soil copper and zinc.These results improved our understanding of fungal ecology of mine wastelands.

Effects of multiple but low pesticide loads on aquatic fungal communities colonizing leaf litter

In the first tier risk assessment（RA） of pesticides, risk for aquatic communities is estimated by using results from standard laboratory tests with algae, daphnids and fish for single pesticides such as herbicides, fungicides, and insecticides. However, fungi as key organisms for nutrient cycling in ecosystems as well as multiple pesticide applications are not considered in the RA. In this study, the effects of multiple low pesticide pulses using regulatory acceptable concentrations（RACs） on the dynamics of non-target aquatic fungi were investigated in a study using pond mesocosm. For that, fungi colonizing black alder（Alnus glutinosa） leaves were exposed to multiple, low pulses of 11 different pesticides over a period of 60 days using a real farmer＇s pesticide application protocol for apple cropping.Four pond mesocosms served as treatments and 4 as controls. The composition of fungal communities colonizing the litter material was analyzed using a molecular fingerprinting approach based on the terminal Restriction Fragment Length Polymorphism（t-RFLP） of the fungal Internal Transcribed Spacer（ITS） region of the ribonucleic acid（RNA） gene（s）. Our data indicated a clear fluctuation of fungal communities based on the degree of leaf litter degradation. However significant effects of the applied spraying sequence were not observed. Consequently also degradation rates of the litter material were not affected by the treatments. Our results indicate that the nutrient rich environment of the leaf litter material gave fungal communities the possibility to express genes that induce tolerance against the applied pesticides. Thus our data may not be transferred to other fresh water habitats with lower nutrient availability.