Extracellular Vesicles From Xylella fastidiosa Carry sRNAs and Genomic Islands, Suggesting Roles in Recipient Cells

Area of Science:

• Microbiology
• Plant Pathology
• Molecular Biology

Background:

• Xylella fastidiosa (Xf) is a Gram-negative bacterial plant pathogen causing significant crop diseases.
• Extracellular vesicles (EVs) are crucial for Xf virulence, carrying various molecular cargo.

Purpose of the Study:

• To investigate the molecular composition and function of Xf-EVs.
• To identify potential virulence factors and mechanisms of horizontal gene transfer (HGT) mediated by Xf-EVs.

Main Methods:

• DNA sequencing (DNA-seq) to analyze EV DNA content.
• RNA sequencing (RNA-seq) to profile EV RNA cargo.
• Bioinformatic prediction of RNA and DNA targets.

Main Results:

• Xf-EVs are enriched with DNA-binding proteins, RNA-binding proteins, genomic islands (GIs), and small RNAs (sXFs).
• Four island-encoded sXFs were identified in EVs, with one predicted to interact with Hfq.
• sXFs target bacterial natural competence genes and a plant immune gene (CNL), suggesting roles in inter-kingdom communication and virulence.

Conclusions:

• Xf-EVs deliver both DNA and RNA cargo, facilitating bacterial gene regulation, HGT, and potentially modulating plant immunity.
• Island-encoded sXFs are highlighted as novel virulence factors.
• Vesiduction is proposed as a mechanism for HGT of sXFs in Xf.