Study of Soil Bacteria Around Citrus Trees Producing Antimicrobial Compounds

Jenn Hoskins
15th July, 2024

Study of Soil Bacteria Around Citrus Trees Producing Antimicrobial Compounds

Image Source: Natural Science News, 2024

Key Findings

  • The study by Centro de Investigación y de Estudios Avanzados focused on genetically modified citrus trees to combat citrus greening disease
  • These trees expressed phloem-targeted antimicrobials, specifically human lysozyme and β-defensin-2, to target the disease-causing bacteria
  • The genetic modifications did not significantly alter the soil microbiome, maintaining soil health and plant growth
Huanglongbing (HLB), also known as citrus greening, is a devastating citrus disease with limited success in prevention and mitigation. HLB is caused by 'Candidatus Liberibacter' spp., fastidious α-proteobacteria that infect citrus trees, leading to severe economic losses worldwide[2]. Traditional methods for managing HLB include the use of antibiotics, pesticides, and the cultivation of pathogen-free seedlings, but these approaches have not been entirely effective[3]. Recent studies have explored various strategies, such as plant defense inducers and antimicrobial peptides, to combat this disease[3][4]. However, a new study conducted by the Centro de Investigación y de Estudios Avanzados has investigated a novel approach using genetically modified citrus trees expressing phloem-targeted antimicrobials[1]. This study focused on the effects of genetically modified citrus trees expressing Citrus sinensis PP16 (CsPP16) fused to human lysozyme and β-defensin-2. These antimicrobials were chosen due to their ability to target vascular tissues, specifically the phloem, where 'Candidatus Liberibacter' spp. reside. The primary concern addressed was whether these genetic modifications would significantly alter the soil microbiome diversity, which is crucial for maintaining soil health and plant growth. Using 16S amplicon analysis, the researchers examined the alpha diversity (the variety of species within a specific area), beta diversity (the difference in species between different areas), phylogenetic diversity (the evolutionary relationships between species), differential abundance (the relative quantity of different species), and functional prediction (the potential functions of the microbial community) between the antimicrobial phloem-overexpressing plants and the control group. The results indicated no significant alterations in any of these parameters, suggesting that the introduction of these genetically modified trees had minimal impact on the microbial community structure in the soil. This finding is significant because it suggests that the use of phloem-targeted antimicrobials in genetically modified citrus trees can help manage HLB without disrupting the soil microbiome. Previous studies have shown that plant defense inducers like β-aminobutyric acid (BABA), 2,1,3-benzothiadiazole (BTH), and 2,6-dichloroisonicotinic acid (INA) can suppress HLB disease and improve fruit yield and quality[4]. However, these chemical treatments can sometimes have broader ecological impacts. The current study provides a promising alternative that specifically targets the pathogen without affecting the surrounding environment. Furthermore, the study revealed distinct bacterial assemblages between the rhizosphere soil (the soil surrounding the plant roots) and the root environments. This differentiation is crucial for understanding how microbial communities interact with plant roots and how these interactions can influence plant health and disease resistance. The minimal impact on soil microbiota observed in this study aligns with the goal of developing sustainable and ecologically friendly strategies for managing HLB. In conclusion, the research conducted by the Centro de Investigación y de Estudios Avanzados offers a promising strategy for controlling HLB through the use of genetically modified citrus trees expressing phloem-targeted antimicrobials. This approach shows minimal impact on soil microbiome diversity, making it a viable and environmentally friendly option for managing this devastating disease. The study builds on previous research by providing a targeted method that could complement existing strategies, such as plant defense inducers and antimicrobial peptides, to effectively combat HLB[3][4].

GeneticsBiochemPlant Science

References

Main Study

1) Metagenomic Analysis of Rhizospheric Bacterial Community of Citrus Trees Expressing Phloem-Directed Antimicrobials.

Published 15th July, 2024

Journal: Microbial ecology

Issue: Vol 87, Issue 1, Jul 2024

Related Studies

2) Citrus huanglongbing: a newly relevant disease presents unprecedented challenges.

https://doi.org/10.1094/PHYTO-12-12-0331-RVW

3) Controlling Citrus Huanglongbing: Green Sustainable Development Route Is the Future.

https://doi.org/10.3389/fpls.2021.760481

4) Field Evaluation of Plant Defense Inducers for the Control of Citrus Huanglongbing.

https://doi.org/10.1094/PHYTO-08-15-0196-R


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