Metabarcoding Analysis Reveals Microbial Diversity and Potential Soilborne Pathogens Associated with Almond Dieback...

Area of Science:

• Plant Pathology
• Microbiology
• Agricultural Science

Background:

• Almond decline and dieback pose significant threats to newly established orchards.
• Symptoms include internal necrosis, canker, and external gummosis, impacting almond production.

Purpose of the Study:

• To investigate the fungal and bacterial agents associated with almond decline and dieback.
• To compare microbial communities across six almond cultivars using metabarcoding and traditional isolation.

Main Methods:

• Utilized metabarcoding and traditional culture plate isolation to identify causative agents.
• Analyzed microbial communities in six different almond cultivars.

Main Results:

• Classical isolation identified 47 fungal species/genera, including *Diaporthe amygdali* and *Fusarium* species.
• Metabarcoding revealed soilborne pathogens like *Neocosmospora rubicola* and *Dactylonectria estremocensis*.
• The 'Soleta' cultivar showed lower microbial richness, indicating increased susceptibility.

Conclusions:

• Almond decline is multifactorial, involving co-infections by opportunistic microbes.
• Pathogens may originate from nursery substrates or shared soils with crops like olives and vineyards.
• Integrating Next-Generation Sequencing (NGS) is vital for understanding complex plant diseases and developing sustainable management strategies.