Effect of an Alltech soil health product on entomopathogenic nematodes, root-knot nematodes and on the growth of tomato plants in the greenhouse

Investigating the Effects of Alltech Crop Science (ACS) Products on Plant Defence against Root-Knot Nematode Infestation

Two formulations of Alltech Crop Science products (ACS), a proprietary blend of fermentation products and plant extracts with micronutrients (ACS5075), and a microbial based product (ACS3048), were tested to understand (1) their impact on the tomato plant immune response and (2) whether they are priming a resistance response in plants against root knot nematodes (RKN). Research findings reported previously indicate that tomato plants pre-treated with ACS5075 and ACS3048 were found less sensitive to Meloidogyne javanica infection. In the current study, the expression of six defence-related genes (PR-1, PR-3, PR-5T, ACO, CAT and JERF 3), relative to a housekeeping gene, were monitored via RT-PCR. Results suggest that the treatment with ACS5075 enhanced ACO and PR-1 gene expression levels, both post- treatment and post-infection with M. javanica. Reduced M. javanica infestation that was reported in the previous study could be attributed to the increased expression of these genes in the ACS5075-treated plants. Tomato plants treated with ACS3048, but without RKN infection, also demonstrated higher levels of ACO and PR-1 gene expression. Subsequently, 2D-gel electrophoresis was performed to study the differential protein expression in leaf tissues of treated tomato plants in an effort to elucidate a possible mechanism of action for these products. Protein spot 1 was identified as 'disease resistance protein RPP13-like', protein spot 2 as 'phosphatidylinositol 4-phosphate 5-kinase 2', spot 3 as 'protein SABRE like' and protein spot 4 as 'uncharacterized protein'. Overall research findings indicate that the ACS products could be used as plant immunity-boosting agents, as they play a significant role in the expression of certain genes and proteins associated with plant defence.

Observations on the interaction between plant growth-promoting bacteria and the root-knot nematode Meloidogyne javanica

Pseudomonas fluorescens, strains L124, L228, L321, and the positive control strain F113 used in this study, produce compounds associated with plant growth promotion, biocontrol, antimicrobial and antiviral activity, and adaptation to stresses. These bacterial strains were tested in vitro and in vivo in tomato plants, to determine their potential role in Meloidogyne javanica suppression. In laboratory experiments, only 2% of M. javanica eggs hatched when exposed to the metabolites of each bacterial strain. Additionally, 100% M. javanica J2 mortality was recorded when nematodes were exposed to the metabolites of F113 and L228. In greenhouse experiments, M. javanica infected tomato plants, which were also inoculated with the bacterial strains F113 and L124, displayed the highest biomass (height, number of leaves, fresh and dry weight) of all bacterial treatments tested. Results from the development and induced systemic resistance experiments indicated that the bacterial strains F113 and L321 had the most effective biocontrol capacity over nematode infection, delayed nematode development (J3/J4, adults and galls), and reduced nematode fecundity. In addition, these results indicated that the bacterial strain L124 is an effective plant growth promoter of tomato plants. Furthermore, it was determined that the bacterial strain L321 was capable of M. javanica biocontrol. P. fluorescens F113 was effective at both increasing tomato plant biomass and M. javanica biocontrol. In an agricultural context, applying successional drenches with these beneficial plant growth promoting rhizobacteria would ensure bacteria viability in the rhizosphere of the plants, encourage positive plant bacterial interactions and increase biocontrol against M. javanica.

Sustainable management of the potato cyst nematode, Globodera rostochiensis, with two microbial fermentation products

Potato cyst nematodes (PCN) cause an overall 9% yield loss of total potato production worldwide. Research on sustainable management of PCN is still under progress. Two microbial fermentation products (MFPs) from Alltech, a proprietary blend formulated with a bacterial fermentation media and a Cu component (MFP5075), and a microbial based product (MFP3048), were evaluated against the PCN Globodera rostochiensis. In laboratory tests, effectiveness of the MFPs was recorded in terms of PCN juveniles (J2) hatching from cysts, J2 mortality and their attraction toward potato roots using pluronic gel. Greenhouse trials were conducted to study the effect of the products on PCN infestation in potato plants and a pilot scale experiment was conducted to study the impact of these MFPs on nematode biodiversity in garden soil. All treatments were performed within a concentration range of 0, 0.5, 1, and 2% (v/v) MFP5075 and 2, 6, 10, and 20 g/10 ml (w/v) MFP3048. The attraction assay, juvenile hatching and the PCN infestation in plants results were compared with those in an untreated control and a commercial nematicide (Nemguard™) treatment. After 24 h of treatment with 0.5 and 1% MFP5075, a 13-fold and 43-fold reduction, respectively, relative to J2 survival was recorded compared to that of untreated control. However, no J2 survived at 2% and above concentration of the MFP5075 treatment. Treatment with MFP3048 was effective in causing mortality of J2 only after 48-h. In the attraction assay, a 20-fold and 8-fold reduction in number of J2 attracted toward potato roots was observed, when treated with MFP5075, compared to the untreated and the Nemguard™ treatment, respectively. Subsequently, 30-35 PCN cysts were treated with both products dissolved in potato root diffusate and the results were recorded in terms of number of J2 hatched in each treatment after 10 days. No J2 hatched in the MFP5075 treatment, whereas mean numbers (±SE) of 243 ± 11.5, 30 ± 2.5, and 1.3 ± 0.6 J2 were noted in the untreated control, MFP3048, and the Nemguard™ treatment, respectively. The treatment with the MFPs compromised the integrity of the unhatched J2, which looked granular, whereas the internal organs of the unhatched J2 could be clearly identified in the untreated control. In plant infestation studies, treatment with MFP3048 and MFP5075 caused 90.6 and 84.9 percent reduction in PCN infestation, respectively, in terms of cysts developed on roots compared to untreated control. Overall, results indicate that the MFPs could potentially provide a promising alternative for sustainable PCN management.

Plant Parasitic Nematodes: A Review on Their Behaviour, Host Interaction, Management Approaches and Their Occurrence in Two Sites in the Republic of Ireland

Plant parasitic nematodes are a major problem for growers worldwide, causing severe crop losses. Several conventional strategies, such as chemical nematicides and biofumigation, have been employed in the past to manage their infection in plants and spread in soils. However, the search for the most sustainable and environmentally safe practices is still ongoing. This review summarises information on plant parasitic nematodes, their distribution, and their interaction with their host plants, along with various approaches to manage their infestations. It also focuses on the application of microbial and fermentation-based bionematicides that have not only been successful in controlling nematode infection but have also led to plant growth promotion and proven to be environmentally safe. Studies with new information on the relative abundance of plant parasitic nematodes in two agricultural sites in the Republic of Ireland are also reported. This review, with the information it provides, will help to generate an up-to-date knowledge base on plant parasitic nematodes and their management practices.

Transcriptome Profiling Combined With Activities of Antioxidant and Soil Enzymes Reveals an Ability of Pseudomonas sp. CFA to Mitigate p-Hydroxybenzoic and Ferulic Acid Stresses in Cucumber

Continuous-cropping leads to obstacles in crop productivity by the accumulation of p-hydroxybenzoic acid (PHBA) and ferulic acid (FA). In this study, a strain CFA of Pseudomonas was shown to have a higher PHBA- and FA-degrading ability in media and soil and the mechanisms underlying this were explored. Optimal conditions for PHBA and FA degradation by CFA were 0.2 g/l of PHBA and FA, 37°C, and pH 6.56. Using transcriptome analysis, complete pathways that converted PHBA and FA to acetyl coenzyme A were proposed in CFA. When CFA was provided with PHBA and FA, we observed upregulation of genes in the pathways and detected intermediate metabolites including vanillin, vanillic acid, and protocatechuic acid. Moreover, 4-hydroxybenzoate 3-monooxygenase and vanillate O-demethylase were rate-limiting enzymes by gene overexpression. Knockouts of small non-coding RNA (sRNA) genes, including sRNA 11, sRNA 14, sRNA 20, and sRNA 60, improved the degradation of PHBA and FA. When applied to cucumber-planted soil supplemented with PHBA and FA, CFA decreased PHBA and FA in soil. Furthermore, a reduction of superoxide radical, hydrogen peroxide, and malondialdehyde in cucumber was observed by activating superoxide dismutase, catalase, glutathione peroxidase, ascorbate peroxidase, glutathione reductase, dehydroascorbate reductase, and monodehydroascorbate reductase in seedlings, increasing the reduced glutathione and ascorbate in leaves, and inducing catalase, urease, and phosphatase in the rhizosphere. CFA has potential to mitigate PHBA and FA stresses in cucumber and alleviate continuous-cropping obstacles.

Continuous Cropping Alters Multiple Biotic and Abiotic Indicators of Soil Health

The continuous cropping (CC) of major agricultural, horticultural, and industrial crops is an established practice worldwide, though it has significant soil health-related concerns. However, a combined review of the effects of CC on soil health indicators, in particular omics ones, remains missing. The CC may negatively impact multiple biotic and abiotic indicators of soil health, fertility, and crop yield. It could potentially alter the soil biotic indicators, which include but are not limited to the composition, abundance, diversity, and functioning of soil micro- and macro-organisms, microbial networks, enzyme activities, and soil food web interactions. Moreover, it could also alter various soil abiotic (physicochemical) properties. For instance, it could increase the accumulation of toxic metabolites, salts, and acids, reduce soil aggregation and alter the composition of soil aggregate-size classes, decrease mineralization, soil organic matter, active carbon, and nutrient contents. All these alterations could accelerate soil degradation. Meanwhile, there is still a great need to develop quantitative ranges in soil health indicators to mechanistically predict the impact of CC on soil health and crop yield gaps. Following ecological principles, we strongly highlight the significance of inter-, mixture-, and rotation-cropping with cover crops to sustain soil health and agricultural production.