Distribution, pathogenicity and disease control of Fusarium tricinctum

Essential oils of thyme (Thymus vulgaris) and oregano (Origanum vulgare) as an alternative for the control of pesticide-resistant Fusarium spp. in quinoa seeds

BACKGROUND

The phytopathogenic genus Fusarium can cause damage such as root and stem rot in economically important crops, with significant implications. To seek a sustainable method for controlling this phytopathogen in seeds, the antifungal activity of essential oils (EOs) from thyme (Thymus vulgaris) and oregano (Origanum vulgare) was evaluated against isolates of F. graminearum, F. equiseti, F. culmorum and F. oxysporum originating from quinoa (Chenopodium quinoa) crops in the Boyacá (Colombia).

RESULTS

Initially, the effectiveness of commercial fungicides against the mentioned phytopathogenic fungi was evaluated. Upon verifying that these isolates exhibited high resistance to these compounds, the EOs were assessed as a potential control alternative. A disk diffusion assay demonstrated complete in vitro inhibition of the growth of the evaluated phytopathogens when undiluted EOs were used. Subsequently, the minimum inhibitory concentration (MIC) of these oils was determined using the agar well diffusion technique, revealing a MIC of 10 and 1 μL mL-1 for thyme and oregano oil, respectively. Following this, the antifungal activity of the EOs applied to quinoa seeds was evaluated, and germination indices were measured as an indirect indicator of their toxicity.

CONCLUSION

Despite both EOs successfully inhibiting microbial growth in the seeds, it was also found that thyme EO at 100 μL mL-1 and oregano EO at 10 μL mL-1 inhibited seed emergence and germination. However, lower concentrations exhibited a reduction in fungal population without affecting these germination indices. Therefore, it is suggested that the use of these compounds has potential in the treatment and disinfection of quinoa seeds. © 2024 Society of Chemical Industry.

Wild rodents seed choice is relevant for sustainable agriculture

Mitigating pre-harvest sprouting (PHS) and post-harvest food loss (PHFL) is essential for enhancing food securrity. To reduce food loss, the use of plant derived specialized metabolites can represent a good approach to develop a more eco-friendly agriculture. Here, we have discovered that soybean seeds hidden underground during winter by Tscherskia triton and Apodemus agrarius during winter possess a higher concentration of volatile organic compounds (VOCs) compared to those remaining exposed in fields. This selection by rodents suggests that among the identified volatiles, 3-FurAldehyde (Fur) and (E)-2-Heptenal (eHep) effectively inhibit the growth of plant pathogens such as Aspergillus flavus, Alternaria alternata, Fusarium solani and Pseudomonas syringae. Additionally, compounds such as Camphene (Cam), 3-FurAldehyde, and (E)-2-Heptenal, suppress the germination of seeds in crops including soybean, rice, maize, and wheat. Importantly, some of these VOCs also prevent rice seeds from pre-harvest sprouting. Consequently, our findings offer straightforward and practical approaches to seed protection and the reduction of PHS and PHFL, indicating potential new pathways for breeding, and reducing both PHS and pesticide usage in agriculture.

Isolation and genome characterization of Paenibacillus polymyxa 188, a potential biocontrol agent against fungi

AIMS

In this work, we aimed to isolate marine bacteria that produce metabolites with antifungal properties.

METHODS AND RESULTS

Paenibacillus polymyxa 188 was isolated from a marine sediment sample, and it showed excellent antifungal activity against many fungi pathogenic to plants (Fusarium tricinctum, Pestalotiopsis clavispora, Fusarium oxysporum, F. oxysporum f. sp. Cubense (Foc), Curvularia plantarum, and Talaromyces pinophilus) and to humans (Aspergillus terreus, Penicillium oxalicum, and Microsphaeropsis arundinis). The antifungal compounds produced by P. polymyxa 188 were extracted and analyzed using matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The complete genome sequence and biosynthetic gene clusters of P. polymyxa 188 were characterized and compared with those of other strains. A total of 238 carbohydrate-active enzymes (CAZymes) were identified in P. polymyxa 188. Two antibiotic gene clusters, fusaricidin and tridecaptin, exist in P. polymyxa 188, which is different from other strains that typically have multiple antibiotic gene clusters.

CONCLUSIONS

Paenibacilluspolymyxa 188 was identified with numerous biosynthetic gene clusters, and its antifungal ability against pathogenic fungi was verified.

Diversity and correlation analysis of different root exudates on the regulation of microbial structure and function in soil planted with Panax notoginseng

Introduction

Specific interactions between root exudates and soil microorganisms has been proposed as one of the reasons accounting for the continuous cropping obstacle (CCO) of Panax notoginseng. However, rotation of other crops on soils planted with P. notoginseng (SPP) did not show CCO, suggesting that root exudates of different crops differentially regulate soil microorganisms in SPP.

Methods

Here, we investigated the microbial community structure and specific interaction mechanisms of the root exudates of the four plant species, P. notoginseng (Pn), Zea mays (Zm), Nicotiana tabacum (Nt) and Perilla frutescens (Pf), in SPP by static soil culture experiment.

Results

The results showed that the chemical diversity of root exudates varied significantly among the four plant species. Pn had the highest number of unique root exudates, followed by Nt, Zm and Pf. Terpenoids, flavonoids, alkaloids and phenolic acids were the most abundant differentially accumulated metabolites (DAMs) in Pn, Nt, Zm and Pf, respectively. However, lipids were the most abundant common DAMs among Zm Nt and Pf. Pn root exudates decreased the relative abundance of bacteria, but increased that of fungi. While specific DAMs in Pn enriched Phenylobacterium_zucineum, Sphingobium_yanoikuyae, Ophiostoma_ulmi and functional pathways of Nucleotide excision repair, Streptomycin biosynthesis, Cell cycle-Caulobacter and Glycolysis/Gluconeogenesis, it inhibited Paraburkholderia _caledonica and Ralstonia_pickettii. However, common DAMs in Zm, Nt and Pf had opposite effects. Moreover, common DAMs in Zm, Nt and Pf enriched Ralstonia_pseudosolanacearum and functional pathway of Xylene degradation; unique DAMs in Zm enriched Talaromyces_purcureogeneus, while inhibiting Fusarium_tricinctum and functional pathways of Nucleotide excision repair and Alanine, aspartate and glutamate metabolism; unique DAMs in Pf enriched Synchytrium_taraxaci.

Discussion

The core strains identified that interact with different root exudates will provide key clues for regulation of soil microorganisms in P. notoginseng cultivation to alleviate CCO.

Antimicrobial activity enabled by chitosan-ε-polylysine-natamycin and its effect on microbial diversity of tomato scrambled egg paste

For a long time, food spoilage posed a severe impairment on food safety and public health. Although chemical preservatives are commonly used to inhibit spoilage/ pathogenic microbial growth, the disadvantages of a single target, potential toxicity and high dose of use limit the better use of preservatives. In this research, the combination of natural preservatives: Natamycin (Nat), ε-polylysine (ε-PL), and Chitosan (CS) could achieve an excellent antimicrobial effect including bacteria and fungi, and reduce the usage of a single preservative. Compound preservatives could destroy microbial morphology and damage the integrity of the cell wall/membrane by leakage of protein and alkaline phosphatase (AKP). Besides, high-throughput sequencing revealed that compound preservatives could decrease microbial diversity and richness, especially, Pseudomonas, Acinetobacter, Fusarium, and Aspergillus. Therefore, the combination of 1/8 × MIC CS, 1/4 × MIC ε-PL, and 1/2 × MIC Nat can achieve an excellent antibacterial effect, providing new ideas for food preservation.