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ORIGINAL RESEARCH article
Front. Microbiol.
Sec. Microbe and Virus Interactions with Plants
Volume 16 - 2025 | doi: 10.3389/fmicb.2025.1568162
This article is part of the Research Topic Climate is Changing: Harnessing Plant-Microbe Interactions For Sustainable Agriculture in Arid Areas View all 3 articles
Often in silico, rarely in vivo: characterizing endemic plantassociated microbes for system-appropriate biofertilizers
Provisionally accepted- 1 Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, Australia
- 2 DairyBio, AgriBio, Centre for AgriBioscience,, Bundoora, Australia
- 3 School of Applied Systems Biology, La Trobe University, Bundoora, Australia
- 4 Department of Microbiology, Anatomy, Physiology and Pharmacology, La Trobe University, Bundoora, Australia
The potential of phosphate-solubilizing microbes (PSMs) to enhance plant phosphorus uptake and reduce fertilizer dependency remains underutilized. This is partially attributable to frequent biofertilizer-farming system misalignments that reduce efficacy, and an incomplete understanding of underlying mechanisms. This study explored the seed microbiomes of nine Australian lucerne cultivars to identify and characterize high-efficiency PSMs. From a library of 223 isolates, 94 (42%) exhibited phosphate solubilization activity on Pikovskaya agar, with 15 showing high efficiency (PSI > 1.5). Genomic analysis revealed that the 'high-efficiency' phosphate-solubilizing microbes belonged to four genera (Curtobacterium, Pseudomonas, Paenibacillus, Pantoea), including novel strains and species. However, key canonical genes, such as pqq operon and gcd, did not reliably predict phenotype, highlighting the limitations of in silico predictions. Mutagenesis of the highefficiency isolate Pantoea rara Lu_Sq_004 generated mutants with enhanced and null solubilization phenotypes, revealing the potential role of 'auxiliary' genes in downstream function of solubilization pathways. Inoculation studies with lucerne seedlings demonstrated a significant increase in shoot length (p < 0.05) following treatment with the enhanced-solubilization mutant, indicating a promising plant growth-promotion effect. These findings highlight the potential of more personalized 'systemappropriate' biofertilizers and underscore the importance of integrating genomic, phenotypic, and in planta analyses to validate function. Further research is required to investigate links between genomic markers and functional outcomes to optimize the development of sustainable agricultural inputs.
Keywords: phosphate solubilization, biofertilizer, lucerne, seed microbiome, Mutation, bacterial genome
Received: 28 Jan 2025; Accepted: 07 Apr 2025.
Copyright: © 2025 Hone, Li, Kaur, Wood and Sawbridge. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Holly Hone, Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, Australia
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