Exploring the diversity and potential interactions of bacterial and fungal endophytes associated with different cultivars of olive (Olea europaea) in Brazil.

The olive crop has expanded in the southeastern region of South America, particularly in Brazil. Thus, the objectives of this study were to identify the diversity of endophytic microorganisms associated with olive leaves with culture-dependent and culture-independent methods, to explore which factors influence the composition and abundance of this microbial community, to identify the trophic mode of these fungi by FunGuild and, to verify type associations between bacterial and fungal communities. Leaf samples were collected from 93 plants in nine locations in the Brazilian states of São Paulo and Minas Gerais. Leaves were first superficially disinfected before fungal isolation and next-generation metabarcoding sequencing was completed targeting the 16S rRNA regions for bacteria and ITS1 for fungi. In total, 800 isolates were obtained, which were grouped into 191 morphotypes and molecularly identified, resulting in 38 genera, 32 of which were recorded for the first time in cultivated olive trees in Brazil. For the isolated fungi, the most abundant trophic level was pathotrophic and for the culture-independent method was unidentified followed by symbiotrophic. The metabarcoding results revealed that factors such as plant age, altitudinal gradient, and geographic location can influence the microbial community of commercial olive plants, while the specific cultivar did not.

Transovarian Transmission of Blochmannia and Wolbachia Endosymbionts in the Neotropical Weaver Ant Camponotus textor (Hymenoptera, Formicidae).

Camponotus is a hyper-diverse ant genus that is associated with the obligate endosymbiont Blochmannia, and often also with Wolbachia, but morphological studies on the location of these bacteria in the queen's ovaries during oogenesis remain limited. In the present study, we used the Neotropical weaver ant Camponotus textor to characterize the ovary using histology (HE) techniques, and to document the location of Blochmannia and Wolbachia during oogenesis through fluorescence in situ hybridization (FISH). This is the first morphological report of these two bacteria in the same host with polytrophic meroistic ovaries and reveals that Blochmannia is found inside late-stage oocytes and Wolbachia is associated with the nuclei of the nurse cells. Our results provide insights into the developmental sequence of when these bacteria reach the egg, with Blochmannia establishing itself in the egg first, and Wolbachia only reaching the egg shortly before completing egg development. Studies such as this provide understanding about the mechanisms and timing of the establishment of these endosymbionts in the host.

Species-specific signatures of the microbiome from Camponotus and Colobopsis ants across developmental stages.

Symbiotic relationships between hosts and bacteria are common in nature, and these may be responsible for the evolutionary success of various groups of animals. Among ants, these associations have been well studied in some genera of the Camponotini, but several questions remain regarding the generality of the previous findings across all the members of this ant tribe and if bacterial communities change across development in these hosts. This study is the first to characterize the bacterial community associated with a colony of the recently recognized genus Colobopsis and three colonies of Camponotus (two distinct species) and show how different the composition of the bacterial community is when compared across the different genera. Our data reveal that Colobopsis (species: Co. riehlii) and Camponotus (species: Ca. floridanus and Ca. planatus) have distinct microbiota, and we were able to verify that the identity of the species contributes more to the bacterial diversity. We also demonstrated that there were no significant differences between colonies of the same species (Camponotus planatus), and between stages of development from different colonies. We did find that some developmental stages have distinct bacteria, confirming that each stage of development could have a specific microbiota. Our results show species are one of the factors that shape the bacterial community in these Camponotini ants. Additional studies of the intra-colonial microbiome of other hosts and across development may reveal additional clues about the function and importance of bacteria in colony recognition, individual and colony health, and nutritional upgrading.

Microbial composition of spiny ants (Hymenoptera: Formicidae: Polyrhachis) across their geographic range.

BACKGROUND: Symbiotic relationships between insects and bacteria are found across almost all insect orders, including Hymenoptera. However there are still many remaining questions about these associations including what factors drive host-associated bacterial composition. To better understand the evolutionary significance of this association in nature, further studies addressing a diversity of hosts across locations and evolutionary history are necessary. Ants of the genus Polyrhachis (spiny ants) are distributed across the Old World and exhibit generalist diets and habits. Using Next Generation Sequencing (NGS) and bioinformatics tools, this study explores the microbial community of >80 species of Polyrhachis distributed across the Old World and compares the microbiota of samples and related hosts across different biogeographic locations and in the context of their phylogenetic history. RESULTS: The predominant bacteria across samples were Enterobacteriaceae (Blochmannia - with likely many new strains), followed by Wolbachia (with multiple strains), Lactobacillus, Thiotrichaceae, Acinetobacter, Nocardia, Sodalis, and others. We recovered some exclusive strains of Enterobacteriaceae as specific to some subgenera of Polyrhachis, corroborating the idea of coevolution between host and bacteria for this bacterial group. Our correlation results (partial mantel and mantel tests) found that host phylogeny can influence the overall bacterial community, but that geographic location had no effect. CONCLUSIONS: Our work is revealing important aspects of the biology of hosts in structuring the diversity and abundance of these host-associated bacterial communities including the role of host phylogeny and shared evolutionary history.