Klebsiella sp. IR6, an endophytic rhizobacteria with potential as a plant growth-promoting agent for Jalapeño pepper (Capsicum annum L.) production.

Plant growth promotion of rice (Oryza sativa L.) with root endophytic bacteria, isolated from wild Solanaceous medicinal plants Solanum nigrum L., Solanum sisymbriifolium Lam., and Solanum virginianum L.

Antagonistic and Plant Growth-Promoting Potential of Endophytic Trichoderma Against Fusarium Root Rot in Loquat (Eriobotrya japonica)

Loquat (Eriobotrya japonica) is highly susceptible to destructive soil-borne Fusarium pathogens, which cause severe vascular wilt and root rot. While Trichoderma species are widely applied as biocontrol agents, the potential of endophytic Trichoderma strains from loquat remains largely unexplored. This study aimed to isolate and evaluate loquat endophytic Trichoderma strains for their antifungal and plant growth-promoting capabilities. Ten isolates were identified through morphological and phylogenetic analyses as belonging to T. asperellum, T. virens and T. hamatum. Antagonistic activity was initially screened in vitro via dual-culture assays, followed by in vivo greenhouse pot experiments. In vitro results revealed that T. asperellum strains (B077R1 and B077B3) and T. virens GFR9 strongly inhibited the mycelial growth of both F. oxysporum and F. solani (inhibition rates > 50.65%), whereas T. hamatum isolates exhibited weaker antagonism (<35.18%). Moreover, T. asperellum B077R1 demonstrated the highest biocontrol efficacy in the greenhouse pot assay, significantly reducing disease severity caused by F. oxysporum and F. solani by 45.99% and 55.50%, respectively. This strain also significantly enhanced plant height, total biomass (fresh and dry weight) and photosynthetic pigment content (p < 0.05). These findings suggest that newly isolated endophytic Trichoderma strains from loquat exhibit robust host compatibility, offering a promising sustainable strategy for managing root rot in perennial fruit crops.

Plant Growth-Promoting Traits of Root Endophytic Actinobacteria from Mangrove Plants in Coastal Thailand

Endophytic actinobacteria are known for their beneficial effects on plant growth, including promoting growth, enhancing stress resistance, and improving nutrient uptake. However, research on the plant growth promotion (PGP) properties of endophytic actinobacteria isolated from mangroves is scarce. In this study, root samples from twelve mangrove species were collected from mangrove forests across five provinces in Thailand. A total of 54 endophytic actinobacteria strains were isolated, representing 7 families and 10 genera, including Streptomyces, Brevibacterium, Corynebacterium, Gordonia, Kocuria, Micrococcus, Micromonospora, Mycobacterium, Nonomuraea, and Rothia. One of these strains potentially represented a novel species within the genus Gordonia. Among the 54 isolates, 20 demonstrated phosphate solubilization, 9 showed potassium solubilization, 26 produced siderophores, and 22 produced indole compounds. Five strains that exhibited various PGP traits were selected for their ACC deaminase activity. Two isolates, Streptomyces sp. CBTP-06 and Brevibacterium sp. CBSO-02, tested positive for ACC deaminase activity. Notably, both strains significantly increased rice seedling growth, shoot length, root length, and root weight compared with those of the uninoculated control. These findings highlight mangrove-derived endophytic actinobacteria as promising bioinoculant candidates with the potential to improve plant growth and productivity in agricultural applications.

Functional characterisation of endophytic bacteria of Drynaria quercifolia L.(J.)Sm: production of hydrolytic enzymes and plant growth-promotion

Endophytes are widely recognised for their ability to enhance plant growth and survival by adapting to the plant’s internal environment. The present study explores the production of hydrolytic enzymes and plant growth-promoting traits in endophytic bacteria isolated from Drynaria quercifolia. Out of the 34 endophytic bacteria isolated, fifteen morphologically distinct bacterial isolates were initially screened for their ability to produce hydrolytic enzymes and plant growth-promoting compounds. Based on their functional attributes, seven distinct isolates were selected for molecular identification using 16S rRNA gene sequencing. Sequence analysis revealed close similarity to Rothia halotolerans, two distinct strains of Agrobacterium tumefaciens, Mycolicibacterium bacteremicum, Rhizobium sp., Microbacterium sp., and Leifsonia shinshuensis. To the best of our knowledge, this is the first study documenting these particular bacterial taxa as endophytes with plant growth-promoting potential associated with D. quercifolia. Among the identified isolates, Agrobacterium tumefaciens demonstrated the most pronounced plant growth–promoting activity.

Antagonistic activity of PGPR isolated from the avocado (Persea americana) rhizosphere on Phytophthora cinnamomi and Lasiodiplodia theobromae

Plant growth-promoting rhizobacteria (PGPR) have proven to be a sustainable alternative for managing plant pathogens. Developing inoculants with these PGPRs requires a rigorous selection of highly effective native bacterial isolates. In the present study, 29 bacterial isolates were obtained from the rhizosphere of ‘Zutano’ avocado (Persea americana Mill.), a rootstock widely used for the commercial cultivar ‘Hass’, from a commercial orchard on the northern coast of Peru. Two antagonistic isolates showing the highest in vitro inhibition capacity were selected to evaluate their efficacy against the pathogens Phytophthora cinnamomi and Lasiodiplodia theobromae, the causal agents of avocado root rot and dieback, respectively. Results demonstrated that Bacillus subtilis exhibited strong in vitro antagonistic activity against P. cinnamomi and L. theobromae, with 44% and 33.33% inhibition, respectively. Additionally, inoculation of B. subtilis in avocado plants infected with P. cinnamomi resulted in an estimated 90% root viability based on a visual disease severity scale, while increasing root dry weight and length by 116.58% and 44.59%, respectively. These results highlight the potential of B. subtilis for the biological control of avocado diseases caused by P. cinnamomi, while Pseudomonas putida showed promising in vitro antagonistic activity.

Integrative functional profiling of rhizospheric and endophytic bacteria reveals Lelliottia aquatilis as a multifunctional PGPR in Himalayan ecosystems

This study introduces L. aquatilis strain MC3 as an emerging candidate for bioinoculant development and one of the first reports for identification of L. aquatilis as multifunctional PGPR from Himalayan ecosystems.