Seed endophytic ammonia oxidizing bacteria in Elymus nutans transmit to offspring plants and contribute to nitrification in the root zone

Danni Liang; Saman Bowatte

doi:10.3389/fmicb.2022.1036897

Seed endophytic ammonia oxidizing bacteria in Elymus nutans transmit to offspring plants and contribute to nitrification in the root zone

Front Microbiol. 2022 Nov 29:13:1036897. doi: 10.3389/fmicb.2022.1036897. eCollection 2022.

Authors

Danni Liang¹, Saman Bowatte^{1

2}

Affiliations

¹ State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, China.
² AgResearch Limited, Grasslands Research Centre, Palmerston North, New Zealand.

Abstract

Background: Ammonia oxidizing bacteria (AOB) in soil are of great biological importance as they regulate the cycling of N in agroecosystems. Plants are known to harbor AOB but how they occupy the plant is an unresolved question.

Methods: Metabarcoding studies were carried out using Illumina MiSeq sequencing to test the potential of seed vectored AOB exchange between plants and soil.

Results and discussion: We found 27 sequences associated with AOB strains belonging to the genera Nitrosospira, Nitrosovibrio, and Nitrosomonas inhabiting Elymus nutans seeds collected from four geographically distanced alpine meadows. Nitrosospira multiformis was the most dominant across the four locations. The AOB community in E. nutans seeds was compared with that of the leaves, roots and soil in one location. Soil and seeds harbored a rich but dissimilar AOB community, and Nitrosospira sp. PJA1, Nitrosospira sp. Nsp17 and Nitrosovibrio sp. RY3C were present in all plant parts and soils. When E. nutans seeds were germinated in sterilized growth medium under greenhouse conditions, the AOB in seeds later appeared in leaves, roots and growth medium, and contributed to nitrification. Testing the AOB community of the second-generation seeds confirmed vertical transmission, but low richness was observed.

Conclusion: These results suggest seed vectored AOB may play a critical role in N cycle.

Keywords: Elymus nutans; ammonia oxidizing bacteria; nitrification; seed endophytes; vertical transmission.

Grants and funding

Financial support was provided by the Project of the Second Tibetan Plateau Scientific Expedition (2019QZKK0302) and the National Natural Science Foundation of China project (32071483).