Build Your Own Mushroom Soil: Microbiota Succession and Nutritional Accumulation in Semi-Synthetic Substratum Drive the Fructification of a Soil-Saprotrophic Morel.

Hao Tan,Yang Yu,Tianhai Liu,Weihong Peng,Renyun Miao,Zhongqian Huang,Jie Tang,Francis M Martin

doi:10.3389/fmicb.2021.656656

Abstract

Black morel, a widely prized culinary delicacy, was once an uncultivable soil-saprotrophic ascomycete mushroom that can now be cultivated routinely in farmland soils. It acquires carbon nutrients from an aboveground nutritional supplementation, while it remains unknown how the morel mycelium together with associated microbiota in the substratum metabolizes and accumulates specific nutrients to support the fructification. In this study, a semi-synthetic substratum of quartz particles mixed with compost was used as a replacement and mimic of the soil. Two types of composts (C1 and C2) were used, respectively, plus a bare-quartz substratum (NC) as a blank reference. Microbiota succession, substrate transformation as well as the activity level of key enzymes were compared between the three types of substrata that produced quite divergent yields of morel fruiting bodies. The C1 substratum, with the highest yield, possessed higher abundances of Actinobacteria and Chloroflexi. In comparison with C2 and NC, the microbiota in C1 could limit over-expansion of microorganisms harboring N-fixing genes, such as Cyanobacteria, during the fructification period. Driven by the microbiota, the C1 substratum had advantages in accumulating lipids to supply morel fructification and maintaining appropriate forms of nitrogenous substances. Our findings contribute to an increasingly detailed portrait of microbial ecological mechanisms triggering morel fructification.

Highlights

Species in the ascomycete genus Morchella are culinary delicacies widely prized in the world, commonly known as morels (Pilz et al, 2007)
The morel fruiting bodies harvested from the substratum supplemented with C1 had a dry-weight yield of 102.10 ± 10.53 g m−2
Comparing the diversity at the same time-points among the three types of substrata, the results show that the bare-quartz (NC) substratum at day 45 had lower bacterial diversity than the two substrata supplemented with composts but reached unexpectedly high fungal diversity at day 90

Summary

Introduction

Species in the ascomycete genus Morchella are culinary delicacies widely prized in the world, commonly known as morels (Pilz et al, 2007). With great ecological and economic importance, the nutritional strategies of morels vary from soil-saprotrophic to biotrophic (Larson et al, 2016; Loizides, 2017; Longley et al, 2019) Their production was once quite dependent on Ecological Processes Associated With Morel-Fructification collection from wild forests (Pilz et al, 2004, 2007). Morchella importuna (Kuo, O’Donnell, and Volk) is a black morel species believed to be soil-saprotrophic while able to form a facultative mycorrhizal-like association with plant-roots (Dahlstrom et al, 2000; Loizides, 2017) It was recently domesticated as a commercial mushroom-crop (Peng et al, 2016) with a rapidly growing scale of cultivation all over the world (Liu et al, 2018; Sambyal and Singh, 2021).

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Conclusion