Inorganic Chemical Fertilizer Application to Wheat Reduces the Abundance of Putative Plant Growth-Promoting Rhizobacteria

A - Papers appearing in refereed journals

Reid, T. E., Kavamura, V. N., Abadie, M., Torres-Ballesteros, A., Pawlett, M., Clark, I. M., Harris, J. and Mauchline, T. H. 2021. Inorganic Chemical Fertilizer Application to Wheat Reduces the Abundance of Putative Plant Growth-Promoting Rhizobacteria. Frontiers in Microbiology. 12 (article), p. 642587. https://doi.org/10.3389/fmicb.2021.642587

AuthorsReid, T. E., Kavamura, V. N., Abadie, M., Torres-Ballesteros, A., Pawlett, M., Clark, I. M., Harris, J. and Mauchline, T. H.
Abstract

The profound negative effect of inorganic chemical fertilizer application on rhizobacterial diversity has been well documented using 16S rRNA gene amplicon sequencing and predictive metagenomics. We aimed to measure the function and relative abundance of readily culturable putative plant growth-promoting rhizobacterial (PGPR) isolates from wheat root soil samples under contrasting inorganic fertilization regimes. We hypothesized that putative PGPR abundance will be reduced in fertilized relative to unfertilized samples. Triticum aestivum cv. Cadenza seeds were sown in a nutrient depleted agricultural soil in pots treated with and without Osmocote⃝R fertilizer containing nitrogen-phosphorous-potassium (NPK). Rhizosphere and rhizoplane samples were collected at flowering stage (10 weeks) and analyzed by culture-independent (CI) amplicon sequence variant (ASV) analysis of rhizobacterial DNA as well as culture- dependent (CD) techniques. Rhizosphere and rhizoplane derived microbiota culture collections were tested for plant growth-promoting traits using functional bioassays. In general, fertilizer addition decreased the proportion of nutrient-solubilizing bacteria (nitrate, phosphate, potassium, iron, and zinc) isolated from rhizocompartments in wheat whereas salt tolerant bacteria were not affected. A “PGPR” database was created from isolate 16S rRNA gene sequences against which total amplified 16S rRNA soil DNA was searched, identifying 1.52% of total community ASVs as culturable PGPR isolates. Bioassays identified a higher proportion of PGPR in non-fertilized samples [rhizosphere (49%) and rhizoplane (91%)] compared to fertilized samples [rhizosphere (21%) and rhizoplane (19%)] which constituted approximately 1.95 and 1.25% in non-fertilized and fertilized total community DNA, respectively. The analyses of 16S rRNA genes and deduced functional profiles provide an in-depth understanding of the responses of bacterial communities to fertilizer; our study suggests that rhizobacteria that potentially benefit plants by mobilizing insoluble nutrients in soil are reduced by chemical fertilizer addition. This knowledge will benefit the development of more targeted biofertilization strategies.

KeywordsRhizosphere; Rhizoplane; Fertilizer; Microbiome; Bacteria; Plant growth-promoting rhizobacteria; PGPR
Year of Publication2021
JournalFrontiers in Microbiology
Journal citation12 (article), p. 642587
Digital Object Identifier (DOI)https://doi.org/10.3389/fmicb.2021.642587
Web address (URL)https://www.frontiersin.org/articles/10.3389/fmicb.2021.642587/full#h4
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Lawes Agricultural Trust
National Environmental Research Council
Funder project or codeBilateral BBSRC - Embrapa. Exploitation of the rhizosphere microbiome for sustainable wheat production
Optimisation of nutrients in soil-plant systems: How can we control nitrogen cycling in soil?
S2N - Soil to Nutrition - Work package 1 (WP1) - Optimising nutrient flows and pools in the soil-plant-biota system
Publisher's version
Copyright license
CC BY
Accepted author manuscript
Copyright license
CC BY
Supplemental file
Copyright license
CC BY
Supplemental file
Output statusPublished
Publication dates
Online11 Mar 2021
Publication process dates
Accepted15 Feb 2021
PublisherFrontiers Media SA
ISSN1664-302X

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