Inoculation of Bacillus cabrialesii modulates plant growth and wilt disease of chickpea cultivars pre-challenged with Fusarium oxysporum f.sp. ciceris.

Evaluation of the Integrated use of Arbuscular Mycorrhizal Fungi and Trichoderma spp. for Yield Improvement in Mustard (Brassica juncea L.)

The present study evaluated the synergistic effects of arbuscular mycorrhizal fungi (AMF) and beneficial rhizospheric microorganisms on the growth, root colonisation, and yield of mustard (Brassica juncea L.), a crop traditionally regarded as a poor or non-mycorrhizal host. A field experiment was conducted during the rabi seasons of 2023–2024 and 2024–2025 at the Research Farm of Nirmal Seeds Pvt. Ltd., Maharashtra, India, using the mustard variety NIMOH-8. The experiment was laid out in a randomised block design (RBD) with seven treatments and three replications. The treatments comprised soil application of a mycorrhizal powder formulation alone or in combination with Trichoderma viride, Trichoderma harzianum, and Pseudomonas fluorescens. Standard agronomic practices were followed throughout the study. Plant growth, yield attributes, and root colonisation were assessed at harvest, and roots were stained using the Phillips and Hayman (1970) technique. The application of bio-inoculants significantly improved growth and yield parameters compared with the untreated control. The highest number of siliquae per plant (541.9), seed yield per plant (14.13 g), and seed yield (23.28 q ha⁻¹) were recorded in T4, which comprised mycorrhizal powder formulation (250 g ha⁻¹) + Trichoderma viride WP (2.5 kg ha⁻¹). Treatment T7 (mycorrhiza + T. viride + Pseudomonas fluorescens) produced comparable results, with 525.7 siliquae per plant and a yield of 23.15 q ha⁻¹. Microscopic examination of stained roots confirmed AMF colonisation in the combined inoculation treatments, characterised by intraradical hyphae, vesicles, external mycelium, and arbuscules; no fungal colonisation was observed in the untreated control. Enhanced root colonisation was associated with improved plant growth and productivity, indicating a positive interaction between AMF and beneficial rhizospheric microorganisms. The study demonstrated that integrating AMF with Trichoderma viride and Pseudomonas fluorescens enhanced mycorrhizal establishment, nutrient acquisition, and mustard productivity. Among the treatments tested, the combination of mycorrhiza and T. viride was the most effective. These findings indicate the potential of microbial consortia as an environmentally compatible strategy for improving mustard yield and crop productivity.

Isolation and Identification of Fusarium oxysporum Causing Cowpea Fusarium Wilt in Hainan and In Vitro Screening of Antagonistic Bacteria

Cowpea (Vigna unguiculata subsp. sesquipedalis, also known as yardlong bean) is an important winter horticultural crop in Hainan, and Fusarium wilt seriously threatens its yield and quality. To clarify the pathogen and screen antagonistic bacteria, surveys were conducted in 14 fields across Hainan’s major cowpea-growing areas. The causal agent was isolated, tested for pathogenicity, and identified using morphological and multigene molecular methods. Meanwhile, rhizosphere and endophytic bacteria from healthy plants were screened by dual culture, and candidate strains were phylogenetically analyzed using whole-genome sequencing (285 orthologous single-copy genes). Fusarium wilt occurred in all 14 fields (mean incidence 15.35%, range 3.20–76.40%). Of 44 fungal isolates, six were highly pathogenic and identified as Fusarium oxysporum. Twenty-two bacterial strains showed stable antagonism against F. oxysporum, with inhibition rates ranging from 42.62% to 68.47%. Phylogenetic analysis based on whole-genome sequences identified 15 Bacillus strains to the species level (12 B. velezensis, 2 B. subtilis, 1 B. tropicus), while the remaining seven strains belonged to Lysinibacillus (1), Pantoea (1), Klebsiella (1), Serratia (2), and Pseudomonas (2). Draft genome sequences of all 22 strains were obtained. This study provides a collection of biocontrol bacterial resources and genomic information for managing cowpea Fusarium wilt.

Promotion of carob (Ceratonia siliqua L.) seedling growth by Streptomyces spp. and Pseudomonas fluorescens in an alkaline and infertile soil

Description of the subject. The sustainable rehabilitation of degraded soils is a major challenge. This study aims to evaluate the potential of indigenous plant-bacteria symbiotic associations for the phytoremediation of a degraded site. Objectives. To isolate and select Plant Growth-Promoting (PGP) bacterial strains adapted to local conditions to enhance the establishment of carob trees (Ceratonia siliqua), a species of significant socio-economic interest. Method. Sixty-four isolates consisting of actinobacteria or Pseudomonas fluorescens were obtained from the rhizosphere of pioneer legumes (Lotus creticus, Retama monosperma) from the site. A phenotypic screening assessed their PGP traits (indole-3-acetic acid [IAA] production, phosphate solubilization, fungal antagonism). The most promising isolates were used to inoculate carob seedlings grown for two months in a nursery on a sterilized substrate composed of the site's native alkaline and infertile soil. Growth parameters were measured and analyzed by Principal Component Analysis (PCA). Results. The screening identified isolates with complementary profiles: RP5 (high IAA production: 36.09 µg·mL-1), RP1 (phosphate solubilization: halo of 11 mm), and CAARL30 (antagonistic activity against Alternaria alternata, Aspergillus sp., Cladosporium sp., and Fusarium sp.). Isolate CAARL35 (Streptomyces sp.) showed a balanced profile of both IAA production and phosphate solubilization. Nursery trials confirmed the effectiveness of the inoculations. PCA identified the most effective treatments: isolate CAARL35, isolates RP1, RP2, RP5 (P. fluorescens), and the synergistic combination GAL4+RP1. Inoculation with CAARL35 induced the most significant improvements, increasing dry biomass by up to 41%, root length by 35%, and the number of leaflets by 77% compared to the non-inoculated control. Conclusions. This study demonstrates the potential of indigenous rhizobacterial strains, particularly Streptomyces sp. CAARL35, as an effective bioinoculant for enhancing carob tree growth under stressful soil conditions. The selection of high-performing plant-bacteria partnerships, adapted to local edaphic constraints, provides a promising and eco-friendly strategy for the rehabilitation of degraded ecosystems.

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 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.

Single spore propagation of native arbuscular mycorrhizal fungi associated with Khasi mandarin and their symbiotic efficacy in maize