Changes in rhizosphere bacterial communities associated with tree decline: grapevine esca syndrome case study

Area of Science:

• Plant Pathology
• Microbiology
• Agronomy

Background:

• Nonspecific decline in perennial crops is difficult to diagnose and prevent.
• Esca disease in grapevines, with identifiable foliar symptoms, was used as a model.
• Understanding rhizosphere bacterial communities is crucial for crop health.

Purpose of the Study:

• To investigate the association of rhizosphere bacteria with grapevine decline.
• To compare bacterial communities in symptomatic versus asymptomatic grapevines.
• To identify specific bacterial taxa potentially linked to grapevine health.

Main Methods:

• Polymerase chain reaction - denaturing gradient gel electrophoresis (PCR-DGGE) for bacterial community fingerprinting.
• Quantitative PCR (qPCR) to quantify bacterial populations.
• Next-generation sequencing (NGS) for detailed rDNA amplicon analysis.
• Sampling from 11 vineyards with symptomatic and asymptomatic grapevines.

Main Results:

• Bacterial communities varied significantly by vineyard location, not by disease presence.
• Quantitative PCR indicated higher abundance of total bacteria and *Pseudomonas* spp. in asymptomatic plants.
• Next-generation sequencing revealed minor bacterial genera (*Salinibacterium*, *Flavobacterium*, *Nocardia*, *Janthinobacterium*) were more prevalent in asymptomatic plants.

Conclusions:

• Rhizosphere bacterial composition differs between vineyard sites.
• Asymptomatic grapevines harbor a greater abundance of total bacteria and *Pseudomonas* spp.
• Specific bacterial genera may play a role in grapevine resilience, warranting further functional investigation.