Pitting the olive seed microbiome

Area of Science:

• Plant-microbe interactions
• Microbiome research
• Olive tree biology

Background:

• The plant holobiont's health depends on plant-microbe interactions.
• Olive seed microbiota remains largely uncharacterized.
• Previous studies have not investigated olive seed microbial communities.

Purpose of the Study:

• To characterize the bacterial, fungal, and archaeal communities in olive seeds.
• To determine if olive genotype influences seed microbial composition.
• To identify the origin of the seed microbiota.

Main Methods:

• Amplicon sequencing of bacterial, fungal, and archaeal communities in seeds of ten olive genotypes.
• Development of a sterile technique for isolating endosphere samples from olive seeds.

Main Results:

• A diverse microbiota was identified in olive seeds, with plant genotype significantly shaping community structure.
• Actinobacteria was the dominant bacterial phylum (41% average abundance), with Streptomyces being a key genus.
• Basidiomycota and Ascomycota were the main fungal phyla, including genera like Malassezia, Cladosporium, and Mycosphaerella.
• A shared microbiome of four bacterial and three fungal genera was found across genotypes.
• Genera such as Streptomyces and Malassezia were detected in both seed and root endospheres of the same trees.

Conclusions:

• This study presents the first characterization of olive seed microbiota, highlighting unique signatures of Malassezia and Streptomyces.
• Olive genotype is a significant factor in shaping seed microbial community composition.
• Evidence suggests potential translocation of microbes from roots to seeds, indicating possible vertical transmission pathways.