Diversity of bacterial and fungal endophytic communities presents in the leaf blades of Sinningia magnifica, Sinningia schiffneri and Sinningia speciosa from different cladus of Gesneriaceae family: A comparative analysis in three consecutive years.

Sinningia is a genus of plants of Gesneriaceae family with species native to Brazil and is a source of several classes of bioactive secondary metabolites, such as quinones, terpenoids, flavonoids, and phenylethanoid glycosides. However, the diversity of endophytic microorganisms associated with them and the impact of endophytes on the biosynthesis of bioactive substances is unknown. Therefore, we sought to evaluate the microbial diversity, behavior, and frequency of endophytes in leaves blades of S. magnifica, S. schiffneri, and S. speciosa. These plants were collected in different regions and environments of Brazil and were studied comparatively for three consecutive years. The total DNA obtained from the blades of the plant leaves were sequenced by the Illumina MiSeq platform, followed by bioinformatics analysis to assess the microbial diversity of endophytes associated with each plant species and study year. The results of the taxonomic diversity showed a dynamic microbial community, which contained several bacterial phyla among them, Actinomycetota, Bacteroidota, Bacillota, and Pseudomonadota, and for the fungal phyla Ascomycota and Basidiomycota. Comparing the three years of study, the richness of the genera, over time, was decreasing, with signs of recovery towards the third year. The alpha and beta diversity indices confirm a great phylogenetic richness in the endophytic communities of bacteria and fungi associated with the leaf blades of Sinningia. However, these communities are comparatively little conserved, showing population and taxonomic changes of the microorganisms over time, possibly as a measure of adjustment to environmental conditions, evidencing both its fragility and versatility against the effects of environmental change on its endophytic microbial communities.

Multiple Plant Growth-Promotion Traits in Endophytic Bacteria Retrieved in the Vegetative Stage From Passionflower.

Bacteria exhibiting beneficial traits like increasing the bioavailability of essential nutrients and modulating hormone levels in plants are known as plant growth promoting (PGP) bacteria. The occurrence of this specific group of bacteria in the endophytic environment may reflect the decisive role they play in a particular condition. This study aimed to determine the taxonomical diversity of the culturable bacterial endophytes, isolated in the vegetative stage of passionflower (Passiflora incarnata), and assess its potential to promote plant growth by phenotypic and genotypic approaches. The sequencing and phylogenetic analysis of the 16S rRNA gene allowed us to classify 58 bacterial endophytes into nine genera. Bacillus (70.7%) was the most dominant genus, followed by Pseudomonas (8.6%) and Pantoea (6.9%). A few isolates belonged to Rhodococcus and Paenibacillus, whereas the genera Lysinibacillus, Microvirga, Xanthomonas, and Leclercia were represented by only one isolate. The strains were tested for nitrogen fixation, phosphate solubilization, indole-acetic-acid synthesis, and siderophore production. Moreover, PGP related genes (nifH, ipdC, asb, and AcPho) were detected by PCR-based screening. Most of the isolates (94.8%) displayed a potential for at least one of the PGP traits tested by biochemical assays or PCR-based screening. Nine strains were selected based on results from both approaches and were evaluated for boosting the Cape gooseberry (Physalis peruviana) germination and growth. All tested isolates improved germination in vitro, and the majority (78%) increased growth parameters in vivo. The results suggested that most of culturable bacteria inhabiting P. incarnata in the vegetative stage could be used as probiotics for agricultural systems. Besides, their occurrence may be associated with specific physiological needs typical of this development stage.