Effect of long term-consecutive monoculture on fungal community structure and function in the rhizosphere of Chinese yam.

Continuous cropping obstacle from Chinese yam (Dioscorea spp.) is widespread in China, and it seriously reduced the yield and quality. Rhizosphere soil microbiome is rich and associated with continuous cropping obstacle. However, the effect of long-term consecutive monoculture (LTCM) of Chinese yam on rhizosphere soil fungal community is still limited. In this study, fields that were consecutively cropped with Chinese yam for 1, 10 and 20 years were subjected to rhizosphere soil fungal analysis. High-throughput sequencing was used to characterize rhizosphere soil fungal community structure and function, and to determine the effect of long-term consecutive monoculture (LTCM). Results indicated that LTCM induced soil acidification, increased concentration of soil available potassium (AK) and available phosphorus (AP), increased the richness but decreased the evenness of fungal community. However, the Shannon index in YF_10Y fungal community showed the lowest value. Increasing years of monoculture resulted in significant differentiation in community composition, marked by a reduction of biocontrol fungi and an increase of pathogens. Additionally, consecutive monoculture decreased the rate of carbohydrate and amino acid degradation. The comprehensive analysis conducted in this study provides insight into rhizosphere fungal structure and function in response to LTCM of Chinese yam. Information obtained in this study could be used for the development of new microbial fertilizers for Chinese yam, which would mitigate the problems associated with continuous monoculture.