Tuber melanosporum shapes nirS-type denitrifying and ammonia-oxidizing bacterial communities in Carya illinoinensis ectomycorrhizosphere soils

Abstract

Background NirS-type denitrifying bacteria and ammonia-oxidizing bacteria (AOB) play a key role in the soil nitrogen cycle, which may affect the growth and development of underground truffles. We aimed to investigate nirS-type denitrifying bacterial and AOB community structures in the rhizosphere soils of Carya illinoinensis seedlings inoculated with the black truffle (Tuber melanosporum) during the early symbiotic stage. Methods The C. illinoinensis seedlings inoculated with or without T. melanosporum were cultivated in a greenhouse for six months. Next-generation sequencing (NGS) technology was used to analyze nirS-type denitrifying bacterial and AOB community structures in the rhizosphere soils of these seedlings. Additionally, the soil properties were determined. Results The results indicated that the abundance and diversity of AOB were significantly reduced due to the inoculation of T. melanosporum, while these of nirS-type denitrifying bacteria increased significantly. Proteobacteria were the dominant bacterial groups, and Rhodanobacter, Pseudomonas, Nitrosospira and Nitrosomonas were the dominant classified bacterial genera in all the soil samples. Pseudomonas was the most abundant classified nirS-type denitrifying bacterial genus in ectomycorrhizosphere soils whose relative abundance could significantly increase after T. melanosporum inoculation. A large number of unclassified nirS-type denitrifying bacteria and AOB were observed. Moreover, T. melanosporum inoculation had little effect on the pH, total nitrogen (TN), nitrate-nitrogen (NO${}_{3}^{-}$-N) and ammonium-nitrogen (NH${}_{4}^{+}$-N) contents in ectomycorrhizosphere soils. Overall, our results showed that nirS-type denitrifying bacterial and AOB communities in C. illinoinensis rhizosphere soils were significantly affected by T. melanosporum on the initial stage of ectomycorrhizal symbiosis, without obvious variation of soil N contents.

Black Truffles Affect Quercus aliena Physiology and Root-Associated nirK- and nirS-Type Denitrifying Bacterial Communities in the Initial Stage of Inoculation

“…The higher concentration of phosphorus may be caused by the ectomycorrhizae ( Dominguez et al, 2012 ) and the functional bacteria in ectomycorrhizosphere soils ( Matthijs et al, 2007 ). Similar to previous studies ( Kang et al, 2020 ; Siebyła and Hilszczañska, 2020 ), truffle inoculation did not affect the organic matter, total nitrogen, and available potassium contents, implying the T. indicum and T. melanosporum have limited influence on these properties of ectomycorrhizosphere soils. The nitrate-nitrogen contents were higher with than without truffle inoculation.…”

“…aliena seedlings were transplanted into nursery pots full with sterilized mixture. The truffles inoculum and inoculation were done as described previously ( Kang et al, 2020 ). The seedlings were inoculated with T. melanosporum (mel.ali) or T. indicum (ind.ali), and uninoculated Q. aliena seedlings served as a control treatment (CK.ali).…”

The Microbiome Structure of the Symbiosis between the Desert Truffle Terfezia boudieri and Its Host Plant Helianthemum sessiliflorum

“…Still, it remains unclear whether the selection of a robust and stable microbiome is possible. To date, the microbiomes of some species, Tuber borchii [ 29 , 30 ], Tuber magnatum [ 31 ], Tuber aestivum [ 32 , 33 , 34 ], Tuber melanosporum [ 35 , 36 , 37 ], Tuber indicum [ 38 , 39 ], and Tuber pseudobrumale [ 40 ] truffles, have been identified. Despite this, little is known about the microbiome structure and composition of desert truffles under mycorrhiza with the host plant.…”

Image_3.tif

“…After 1 month, the Q. aliena seedlings were transplanted into nursery pots full with sterilized mixture. The truffles inoculum and inoculation were done as described previously (Kang et al, 2020). The seedlings were inoculated with T. melanosporum (mel.ali) or T. indicum (ind.ali), and uninoculated Q. aliena seedlings served as a control treatment (CK.ali).…”