Caradus John

Dr. Caradus John

Grasslanz Technology Ltd
orcid

Research Focus & Metrics

Academic Career Length

36Years (1991-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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27 November 2020 in Journal of Fungi
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Journal Article
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Caradus JohnCaradus John
Caradus John
LJLinda J. Johnson
Linda J. Johnson
The relationship between Epichloë endophytes found in a wide range of temperate grasses spans the continuum from antagonistic to mutualistic. The diversity of asexual mutualistic types can be characterised by the types of alkaloids they produce in planta. Some of these are responsible for detrimental health and welfare issues of ruminants when consumed, while others protect the host plant from insect pests and pathogens. In many temperate regions they are an essential component of high producing resilient tall fescue and ryegrass swards. This obligate mutualism between fungus and host is a seed-borne technology that has resulted in several commercial products being used with high uptake rates by end-user farmers, particularly in New Zealand and to a lesser extent Australia and USA. However, this has not happened by chance. It has been reliant on multi-disciplinary research teams undertaking excellent science to understand the taxonomic relationships of these endophytes, their life cycle, symbiosis regulation at both the cellular and molecular level, and the impact of secondary metabolites, including an understanding of their mammalian toxicity and bioactivity against insects and pathogens. Additionally, agronomic trials and seed biology studies of these microbes have all contributed to the delivery of robust and efficacious products. The supply chain from science, through seed companies and retailers to the end-user farmer needs to be well resourced providing convincing information on the efficacy and ensuring effective quality control to result in a strong uptake of these Epichloë endophyte technologies in pastoral agriculture.

1 December 2023 in New Zealand Journal of Agricultural Research
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Journal Article
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Caradus JohnCaradus John
Caradus John
Food and feed has been produced from genetically modified (GM) crops for 25 years. It is timely to review whether this technology has globally delivered the expected benefits and whether the ongoing debate on risks is justified. Expected benefits associated with GM include increased crop yields, reduced pesticide and insecticide use, reduced carbon dioxide emissions, improved soil structure, improved crop nutritive quality/value, and decreased costs of production. Concerns focus on food safety linked to toxicity and allergenicity, environmental risks associated with potential chances of gene flow, adverse effects on non‐target organisms, evolution of resistance in weeds and insects, and genetic perturbations resulting in unintended compounds, new diseases, or antibiotic resistance. This review focusing on benefits and risks of GM crops concludes that they are a valuable option for delivering improved economic and environmental outcomes by providing solutions for many of the challenges facing mankind. GM technologies like many non‐GM technologies can bring risks, but these can and have been monitored and quantified, allowing decisions balancing commercial, societal and environmental benefits against measurable risks. While ‘checks’ and ‘balances’ are required, regulatory schemes must focus on balancing risks and benefits and not on ‘checks’ alone which is the case for many countries.

24 September 2021 in Plants
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Journal Article
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Stuart D. CardStuart D. Card
Stuart D. Card
Daniel A. BastíasDaniel A. Bastías
Daniel A. Bastías
Caradus JohnCaradus John
Caradus John
Epichloë is a genus of filamentous fungal endophytes that has co-evolved with cool-season grasses with which they form long-term, symbiotic associations. The most agriculturally important associations for pasture persistence for grazing livestock are those between asexual vertically transmitted Epichloë strains and the pasture species, perennial ryegrass, and tall fescue. The fungus confers additional traits to their host grasses including invertebrate pest deterrence and drought tolerance. Selected strains of these mutualistic endophytes have been developed into highly efficacious biocontrol products and are widely utilized within the Americas, Australia, and New Zealand for pasture persistence. Less publicized is the antagonism Epichloë endophytes display towards multiple species of saprophytic and pathogenic microbes. This opinion piece will review the current literature on antimicrobial properties exhibited by this genus of endophyte and discuss the reasons why this trait has historically remained a research curiosity rather than a trait of commercial significance.

10 September 2023 in GM Crops & Food
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Caradus JohnCaradus John
Caradus John
Innovation in agriculture has been essential in improving productivity of crops and forages to support a growing population, improving living standards while contributing toward maintaining environment integrity, human health, and wellbeing through provision of more nutritious, varied, and abundant food sources. A crucial part of that innovation has involved a range of techniques for both expanding and exploiting the genetic potential of plants. However, some techniques used for generating new variation for plant breeders to exploit are deemed higher risk than others despite end products of both processes at times being for all intents and purposes identical for the benefits they provide. As a result, public concerns often triggered by poor communication from innovators, resulting in mistrust and suspicion has, in turn, caused the development of a range of regulatory systems. The logic and motivations for modes of regulation used are reviewed and how the benefits from use of these technologies can be delivered more efficiently and effectively is discussed.

19 December 2021 in Journal of the Royal Society of New Zealand
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Caradus JohnCaradus John
Caradus John
SGStephen L. Goldson
Stephen L. Goldson
DMDerrick Moot
Derrick Moot
JRJacqueline S. Rowarth
Jacqueline S. Rowarth
ASAlan V. Stewart
Alan V. Stewart
The New Zealand economy is export‐driven and heavily reliant on the productivity of the pastoral sector. The transformation of native forest and tussock grassland ecologies to temperate grasslands occurred rapidly with the arrival of Europeans. However, this transplanted ecology required the development and use of plant, microbial, animal and management technologies for successful grassland farming. These have enabled New Zealand pastoral agriculture to compete effectively in international markets, without subsidies. The extensive list of plant‐based and associated microbial‐based adaptations, and the management strategies that have enabled the development of highly productive grasslands are described and reviewed. Credible science is required to inform the debate on the environmental impacts of pasture production to avoid misinformation proliferating. This needs transparent and objective integrity from the science community using funding that seeks no defined or preconceived outcomes. Critically, much of the success of New Zealand pastoral farming has been due to the willingness and ability of farmers to use, adapt, adopt and integrate new ideas and technologies into their farming systems. Historic, current and future challenges, and threats that impact on the productivity and sustainability of pastoral agriculture are described and the means to achieve further technology development to manage these is discussed.

7 July 2020 in New Zealand Journal of Agricultural Research
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Journal Article
Open access
Caradus JohnCaradus John
Caradus John
Stuart D. CardStuart D. Card
Stuart D. Card
SFSarah C Finch
Sarah C Finch
DHDavid E. Hume
David E. Hume
LJLinda J. Johnson
Linda J. Johnson
APAlison Popay
Alison Popay
In identifying endophytes for use in pastures in New Zealand there have been two strategies used, either exclusion of ergopeptine and lolitrem alkaloids or, retaining some ergopeptine expression to enhance the stability of natural defences against invertebrate pests. Both have their strengths and weaknesses. It is a matter of balancing these to ensure the end‐user has access to a product that satisfies their needs – a persistent pasture with low to nil animal toxicity in terms of animal production and welfare. The range and intensity of ergot alkaloids in grazed pasture on both pasture and ruminants is reviewed, with emphasis on New Zealand. Ergot alkaloids associated with pasture are produced by associations between certain Epichloë endophyte strains and temperate grasses. Ergot alkaloids have been shown to improve persistence of pasture through providing resistance/deterrence to insect pests as well as deterring grazing animals. However, ergovaline is toxic to grazing animals. Some commercially available ryegrass‐endophyte associations can produce ergovaline concentrations close to those found in associations between ryegrass and the standard endophyte. It is feasible to eliminate ergot alkaloids from pasture grasses in New Zealand as endophyte strains are commercially available that do not express ergovaline and yet still provide excellent pest resistance.