Biology subjects

Vaccaro, F.

Publications and source records attributed to Vaccaro, F..

3 recordsLinked to original sources

bioRxiv2026

Wild rice Oryza rufipogon outperforms cultivated rice in stimulating beneficial bacterial endophytes.

Beneficial interactions between plants and microorganisms strongly influence plant health and productivity, and root exudates play a central role in shaping these associations. This study analyzed the transcriptional responses of the bacterial endophytes Enterobacter asburiae RCA24 and Kosakonia sacchari RCA25 to root exudates from two commercial Italian rice accessions (Oryza sativa Baldo and Vialone Nano) and from an accession of the wild progenitor of tropical rice, Oryza rufipogon. Bacterial transcriptome analyses revealed that RCA24 responds differently to O. sativa varieties and that RCA25 was more stimulated by O. rufipogon. Changes in bacterial gene expression were mainly related to central metabolism, stress response, and signal transduction, highlighting a precise pattern of interaction. On the other hand, transcriptome analysis of inoculated rice revealed that RCA24 triggered broader transcriptional changes in plants than RCA25. Differentially expressed genes were related, especially in shoots, to defense responses, hormone-mediated signaling, and ribosome biogenesis, revealing that plants discriminate bacterial strains in a genotype-specific manner at the transcriptional level. Our findings suggest that traits beneficial to plant-soil microbiota interactions present in O. rufipogon and lost during domestication and diversification could be identified and reintroduced into modern rice varieties to improve sustainable field performance through beneficial microbial associations.

plant biology↗

bioRxiv2025

Bacterial community studies and novel Bradyrhizobium and Rhizobium strains from drought-tolerant legumes grown in Namibia

AimsAnalysis of the microbiota associated with root nodules of five species of drought-tolerant legumes grown in Namibia. These legumes were Lablab purpureus, Vigna radiata, Vigna unguiculata, Macrotyloma uniflorum, and Vigna aconitifolia. Methods16S rRNA gene amplicon sequencing analysis and isolation of rhizobial and non-rhizobial bacterial strains from root nodules was performed. Plant growth-promoting traits were assessed on some isolates and the genomes of four rhizobial strains were sequenced. ResultsThe microbiota analysis revealed Bradyrhizobium as the most prevalent genus in the root nodules, while most of the non-rhizobial community included members of Bacillus genus. In addition, a strain of Variovorax paradoxus was also isolated from V. unguiculata, representing the first documented isolation and characterization report in Namibia. In vitro phenotypic characterization of the non-rhizobial nodule endophytes indicated that they possessed several plant growth-promoting traits. The four rhizobial strains isolated were taxonomically affiliated to the genera Bradyrhizobium and Rhizobium. Genome sequencing revealed that these strains possibly belong to novel species since they share only a limited similarity (dDDH values<70%) to already known species. Impact StatementThis study demonstrated that drought-tolerant legume species harbour microbial diversity from Namibian soil, which allowed us to increase our knowledge on plant-associated bacteria and their possible use in sustainable farming systems, as potential bioinoculants for crop production and for soil revitalization. Utilizing locally isolated bacterial strains as microbial bioinoculants maximizes their compatibility with the local conditions increasing the potential for positive effects on plant health and ecosystem functioning.

microbiology↗

bioRxiv2025

Comparative Analysis of the Microbiota of Vaccinium myrtillus and Vaccinium uliginosum in the Central Italian Apennines

Vaccinium is a genus of shrubs known for their antioxidant and anti-inflammatory compounds. While the commercially cultivated blueberry (V. corymbosum) originates from North America, European species like myrtillus (bilberry) and V. uliginosum (bog bilberry) remain uncultivated due to poor adaptability to conventional growing media. At present, bilberries, which are more valued for fresh consumption, are exclusively harvested from wild populations, particularly in subalpine and mountain environments, where unique soil and climate conditions prevail. This study explores the bacterial and fungal communities associated with V. myrtillus and V. uliginosum in wild populations of the Central Italian Apennines, using 16S rRNA and ITS amplicon sequencing. Microbiota from plant and soil were analyzed, revealing distinct microbial community compositions based on species and plant compartments. Bacterial diversity was highest in bulk soil, while fungal diversity dominated plant tissues. Co-occurrence network analysis showed greater connectivity in V. uliginosum microbiota, suggesting higher resilience. Functional predictions indicated roles in nitrogen cycling, cellulose degradation, and plant-microbe interactions. These findings offer insights into the native microbiota of wild Vaccinium species and could inform conservation and cultivation efforts.

microbiology↗