The negative impacts of climate change on native forest ecosystems have created challenging conditions for the sustainability of natural forest regeneration. These challenges arise primarily from abiotic stresses that affect the early stages of forest tree development. While there is extensive evidence on the diversity of juvenile microbial symbioses in agricultural and fruit crops, there is a notable lack of reports on native forest plants. This review aims to summarize the critical studies conducted on the diversity of juvenile plant–microbe interactions in forest plants and to highlight the main benefits of beneficial microorganisms in overcoming environmental stresses such as drought, high and low temperatures, metal(loid) toxicity, nutrient deficiency, and salinity. The reviewed studies have consistently demonstrated the positive effects of juvenile plant–microbiota interactions and have highlighted the potential beneficial attributes to improve plantlet development. In addition, this review discusses the beneficial attributes of managing juvenile plant–microbiota symbiosis in the context of native forest restoration, including its impact on plant responses to phytopathogens, promotion of nutrient uptake, facilitation of seedling adaptation, resource exchange through shared hyphal networks, stimulation of native soil microbial communities, and modulation of gene and protein expression to enhance adaptation to adverse environmental conditions.

The diversity of orchid mycorrhizal fungi (OMF) and other beneficial root-associated fungi in temperate forests has scarcely been examined. This study aimed to analyze the diversity of mycorrhizal and rhizosphere-associated fungal communities in the terrestrial orchids Gavilea lutea and Chloraea collicensis growing in high-orchid-population-density areas in the piedmont of the Andes Cordillera with native forest (Nothofagus-Araucaria) and Coastal Cordillera with an exotic plantation (Pinus-Eucalyptus) in south-central Chile. We focused on rhizosphere-inhabiting and peloton-associated OMF in a native forest (Andes Cordillera) and a mixed forest (Coastal Cordillera). The native terrestrial orchids G. lutea and C. collicensis were localized, mycorrhizal root segments were taken to isolate peloton-associated OMF, and rhizosphere soil was taken to perform the metabarcoding approach. The results revealed that Basidiomycota and Ascomycota were the main rhizosphere-inhabiting fungal phyla, showing significant differences in the composition of fungal communities in both sites. Sebacina was the most-abundant OMF genera in the rhizosphere of G. lutea growing in the native forest soil. In contrast, Thanatephorus was the most abundant mycorrhizal taxa growing in the rhizosphere of orchids from the Coastal Cordillera. Besides, other OMF genera such as Inocybe, Tomentella, and Mycena were detected. The diversity of OMF in pelotons differed, being mainly related to Ceratobasidium sp. and Tulasnella sp. These results provide evidence of differences in OMF from pelotons and the rhizosphere soil in G. lutea growing in the Andes Cordillera and a selection of microbial communities in the rhizosphere of C. collicensis in the Coastal Cordillera. This raises questions about the efficiency of propagation strategies based only on mycorrhizal fungi obtained by culture-dependent methods, especially in orchids that depend on non-culturable taxa for seed germination and plantlet development.

Rice is a priority crop in Cuba, and bacterial inoculants could help sustain productivity under reduced mineral fertilizer inputs. However, evidence describing the main stages involved in developing these bioproducts in the country remains limited. This study aimed to evaluate the suitability of a bacterial strain as the active microbial ingredient of a prototype rice inoculant for application under reduced nitrogen fertilization. Three promising bacterial strains were evaluated for their effects on rice yield components under field conditions at 60% of the recommended N fertilization rate. The taxonomic affiliation of the selected strain was assessed by multilocus phylogenetic analysis of the recA, rpoB, and glnII genes. The microbiological stability of inoculant formulations supplemented with CaCl₂ or sodium alginate was evaluated during storage at 4 °C and room temperature for 231 days. Inoculant production was scaled up to working volumes of 30 and 300 L, and the resulting prototype was evaluated in a second field experiment at 30% of the recommended N fertilization rate. Among the inoculated treatments, strain Rpd16 produced the highest numbers of panicles per square meter and total and filled grains per panicle. This strain was selected as the active microbial ingredient and was phylogenetically affiliated with the Agrobacterium pusense lineage. After 231 days at 4 °C, all formulations contained viable cell concentrations above 10⁸ CFU mL⁻¹. Compared with the uninoculated treatment receiving the same N fertilization rate, seed bio-priming with the prototype inoculant, provisionally named Azofert-A, was associated with higher tiller number (5.6%), plant height (10.7%), flag leaf length (9.9%), flag leaf dry weight (41.2%), and grain yield (20.4%), providing preliminary evidence of its agronomic potential under reduced N fertilization. This study integrates the main stages involved in developing a prototype bacterial inoculant for rice under Cuban conditions.