Nitrates and Microbiome Components Engaged in Denitrification within Soil Regulate Morchella spp. Growth

Morels (Morchella spp.) are a kind of rare and precious edible fungus and have been successfully cultivated in many places. Currently, the widespread cultivation of morels poses a significant challenge owing to their demanding environmental requirements. Soil properties and the soil microbiome are thought to play pivotal roles in morel growth. However, it remains unknown what factors exert a decisive influence on morel growth. In this study, soils with different morel yields were studied in nine sites from four locations. The basic soil physical and chemical properties were measured. In addition, the soil microbiome was analyzed using high-throughput metagenomic sequencing. We found that soil pH, nitrogen, carbon and conductivity were key indicators for the impact on microbial communities in soil for cultivating morels. Among these, nitrate was more positively associated with morel yield. The soil microbial diversity was more abundant in the soil with a high morel yield. Moreover, certain unknown archaea might be unfavorable to morel growth. The microbes that perform incomplete denitrification (no step of N2O reduction to N2) and nitrogen fixation were positively and negatively correlated with morel growth, respectively. In summary, morels prefer to live in nutrient-rich soils with a variety of microbes and are supported by nitrate and microbiome components involved in denitrification. The findings elucidate a pivotal mechanism in eliciting morel fructification and provide valuable insights for guiding production practices.