ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Plant Systems and Synthetic Biology
This article is part of the Research TopicPlant Molecular Biology and Microbiome Engineering: Next-Generation Strategies for Multi-Stress ResilienceView all 10 articles
Pseudomonas parafulva SAPEU-1 as a Keystone Modulator: Reshaping Citrus Phyllosphere Microbiome to Suppress Citrus Canker
Provisionally accepted
Suhail Asad1*
Peng Gu1Fuyu Jiang1
Liu Jie1Mei Chen1
Samantha Chandranath Karunarathna2Muhammad Atiq3Muhammad Younas4Pinnaduwage Neelamanie Yapa5Xurundong Kan1Jianqiang Zhang1- 1Pu'er University, Pu'er, China
- 2Qujing Normal University, Qujing, China
- 3University of Agriculture Faisalabad Faculty of Agriculture, Faisalabad, Pakistan
- 4Fujian Agriculture and Forestry University, Fuzhou, China
- 5Rajarata University of Sri Lanka, Mihintale, Sri Lanka
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Citrus canker disease, caused by the pathogen Xanthomonas citri subsp. citri (Xcc) poses a substantial challenge for citrus production due to the limited efficacy of chemical control and increasing pathogen resistance. In this study, we isolated an endophytic bacterial strain, Endophyte S2, from the phyllosphere of citrus plants in Yunnan Province, China. We evaluated its efficacy both as a biocontrol agent and as a modulator of the citrus leaf microbiome. In vitro antagonism assays revealed that Endophyte S2 achieved the highest inhibition rate (68.2 %) against Xcc among all tested isolates. Molecular identification based on 16S rRNA gene sequencing classified S2 as Pseudomonas parafulva SAPEU-01. In greenhouse trials, citrus plants with Xcc infestation were treated with SAPEU-01, and phyllosphere samples were collected before treatment and one month after, and analysed by Illumina MiSeq sequencing. Post-treatment, α-diversity (richness and evenness) increased significantly, and β-diversity (PCoA, Bray–Curtis) showed a clear separation of microbial community structure, with reduced intra-group variability. Taxonomic shifts included the enrichment of Proteobacteria (particularly Pseudomonadaceae and Sphingomonadaceae), as well as genera such as Pseudomonas, Sphingomonas, and Methylobacterium, concomitant with a marked decline in Xanthomonadaceae (including X. citri) and opportunistic taxa such as Escherichia coli O157:H7 and Klebsiella aerogenes. Beneficial taxa, including Leuconostoc tardus, Sphingomonas, and Curtobacterium luteum, also increased. These results suggest Pseudomonas parafulva SAPEU-01 not only suppresses the pathogen but also restructures the phyllosphere microbiome toward greater stability and potential resilience.
Keywords: biological control, endophytic bacteria, microbiome engineering, plant pathogens, plant–microbe interactions
Received: 19 Dec 2025; Accepted: 11 Feb 2026.
Copyright: © 2026 Asad, Gu, Jiang, Jie, Chen, Karunarathna, Atiq, Younas, Yapa, Kan and Zhang. 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: Suhail Asad
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