Soil Microbial Communities in Lemon Orchards Affected by Citrus Mal Secco Disease

Area of Science:

• Plant pathology
• Soil microbiology
• Fungal genomics

Background:

• Mal secco is a destructive citrus vascular disease caused by the fungus *Plenodomus tracheiphilus*.
• Infected plant debris in soil acts as a primary source for root infections, initiating disease spread.

Purpose of the Study:

• To investigate the soil bacterial and fungal communities in lemon orchards affected by mal secco.
• To understand the impact of mal secco disease on soil microbiome composition and diversity.

Main Methods:

• Soil samples were collected from five mal secco-affected lemon orchards in Sicily, Italy.
• Total genomic DNA was extracted for fungal DNA quantification via qPCR.
• Bacterial and fungal communities were profiled using 16S and ITS amplicon high-throughput sequencing, respectively.
• Beta diversity analysis and core community analysis were performed to assess microbial community structure.

Main Results:

• Fungal DNA of *Plenodomus tracheiphilus* was detected in all sampled orchards.
• Significant variations in bacterial and fungal community composition were observed across orchards.
• The dominant bacterial phyla included Proteobacteria, Actinobacteriota, and Acidobacteriota, with fluctuating abundances.
• Ascomycota was the dominant fungal phylum, with variable Basidiomycota and Mortierellomycota abundances.
• Putative beneficial bacteria were significantly enriched in infected soil samples, indicating complex microbial interactions.

Conclusions:

• The soil microbiome composition varies significantly in lemon orchards with mal secco infections.
• The enrichment of beneficial bacteria in infected soils suggests potential roles in disease modulation or resilience.
• Further research into these microbial interactions could inform strategies for managing mal secco disease in citrus.