NZ school children discover the power of mānuka in quest for weed killer

 

Schools and pupils from all over New Zealand are working with the University of Otago and Plant & Food Research to discover what secrets are locked within the wide variety of mānuka around the country.

They are exploring whether their local mānuka plants contain enough of a chemical  called grandiflorone to kill weeds, and whether the grandiflorone levels differ in mānuka growing in different parts of New Zealand.

This could result in the native plant’s leaf chemistry providing a natural weed killer.

The nectar from mānuka produces high-value mānuka honey, the basis of a boom in bee keeping around natural mānuka stands and extensive new plantings.

The leaf chemistry could provide an additional valuable product and may be important for the growth of this native plant.

Scientists Elaine Burgess, from Plant & Food Research, and Dr Dave Warren, from the Department of Chemistry at the University of Otago, are leading the project which has been supported by the Government’s “Unlocking Curious Minds” fund.

“Pupils collect foliage from their local mānuka, they then prepare a sample voucher, and extracts are made to test for herbicidal (weed killer) activity in a lettuce seedling assay,” Elaine says.

“They then send us sample extracts to analyse in our Plant & Food Research labs in Dunedin.”

Results are being uploaded to the database NatureWatchNZ to enable schools to compare the variations within mānuka in their own region, plus the differences around wider New Zealand.

 The project is already providing new scientific knowledge.

“Students at Musselburgh School in Dunedin have helped us discover quite big chemical differences in varieties of mānuka in the local area, so it’s a surprise to learn mānuka from a particular region will not necessarily have the same levels of grandiflorone,” explains Dr Warren.

A crucial aspect of the research is testing whether extracts from various mānuka plants stop lettuce seeds from growing.  Initial results show New Zealand mānuka are generally less potent than a related Australian species.

The focus now is to spread the hands-on testing kits around New Zealand to see if there is a mānuka variation here equal to, if not better than, the Australian plant.

“We’ve been very excited by the research so far, and look forward to the kits being circulated to places like the East Cape where we know there are significant amounts of mānuka,” Elaine Burgess says.

So far around 30 schools have been sent the kits, which include all the equipment and instructions necessary for the students to conduct the scientific investigations themselves.

Testing is spread over approximately two weeks, including collecting local mānuka, drying and pressing botanical voucher specimens, and extracting and testing on lettuce seeds.

“This is citizen science in action. We want students to not only gain new skills from conducting the experiments themselves, but also to learn about the nature of science, of testing, of researching and of coming to robust scientific conclusions,” Dr Warren says.

Results from the first wave of testing are being collated at Plant & Food Research in Dunedin while the next bundle of kits are being distributed to more schools around New Zealand.

The project is expected to continue for several years, dependent on further funding for this community science initiative.

Source: University of Otago

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Doctors are reminded of health threat from toxic tutu’s potential to taint honey

Toxins from native tutu plants can contaminate honey, causing vomiting and neurological symptoms (such as seizures) for those who eat it.

Reflecting on a case in 2008, when three family members were poisoned after eating local honey, medical researchers emphasise there is still a significant risk of toxic honey production in the warmer parts of New Zealand.

But because the toxin isn’t present in tutu pollen, researchers are unsure about how it gets into the honey, though passion vine hoppers feeding on the plants might be to blame.

The incident in 2008 led to the development of new food safety standards for New Zealand honey in 2016.

While it raised public and medical awareness of honey poisoning at that time, the authors of a new study think it has slipped from public memory. They say doctors need to be informed of this risk and know how best to manage it. The incident in question led to the development of new food safety standards for New Zealand honey in 2016.

A media release from the New Zealand Medical Association provides an abstract of the paper, which has been published by the New Zealand Medical Journal.

AIM: In autumn 2008, an outbreak of toxic honey poisoning was identified. The outbreak was not recognised initially until three cases from one family group presented to hospital, with a common factor of recent consumption of locally produced honey. The aim of this study was to investigate potential cases of this honey poisoning and determine which toxin was involved.

METHOD: The incident was investigated retrospectively by Waikato District Health Board’s Population Health unit and the New Zealand Food Safety Authority (NZFSA). Identified patients were followed up by questionnaire to gather case information. HortResearch (now Plant and Food Research) tested honey samples for toxins.

RESULTS: The causative agent was identified as tutin, which comes from the New Zealand native plant tutu (Coriariaarborea) which has long been known as a potential source of contamination of honey produced in the warmer parts of New Zealand. Retrospective case investigation identified a total of 22 possible or probable cases, based on a clinical case definition. The spectrum of toxic effects reported were broadly similar to those previously described for tutin, derived either directly from the plant itself or indirectly from honey. There were 13 samples of honey, linked to symptomatic individuals, which were available for testing. Of these, 10 were positive for tutin and its hydroxy metabolite hyenanchin (hydroxytutin) and one was positive for hyenanchin alone.

CONCLUSION: Toxic honey production is a significant risk in parts of New Zealand. Beekeepers and health professionals need to be informed of this risk and know how best to manage it. Due to this poisoning incident, public and professional awareness of honey poisoning has been substantially enhanced. This incident led to development of new food safety standards for New Zealand honey.

The research involved the University of Otago, the Ministry for Primary Industries and the National Poisons Centre.

Source: Scimex

Endangered beetle faces ‘unholy alliance’ of rabbits and redbacks

An “unholy alliance” between rabbits and Australian redback spiders is threatening the existence of an endangered New Zealand species, a study led by AgResearch has shown.

Carried out with the Department of Conservation (DOC) and University of Otago, the study has illustrated the struggle for the ongoing survival of the Cromwell chafer beetle – a nationally endangered native species that can now be found only in the 81 hectare Cromwell Chafer Beetle Nature Reserve between Cromwell and Bannockburn, in Central Otago.

The study found numerous rabbit holes that provided shelter for the rabbits were also proving ideal spaces for the redback spiders to establish their webs. Investigation of those webs in the rabbit holes found the Cromwell chafer beetle was the second-most commonly found prey of the spiders.

These findings “give a fascinating insight into the almost accidental relationships that can develop between species in the natural world, and how that can impact on other species,” says AgResearch Principal Scientist Dr Barbara Barratt.

As a result of the research, DOC has carried out a programme to break down old rabbit holes and hummocks in the reserve to destroy spider nests, and does regular rabbit control. An annual survey for beetle larvae with AgResearch will show whether these actions are having an effect.

Beetle larvae will be surveyed next summer to see what effect reducing redback spider nests is having on the Cromwell chafer beetle.

The Cromwell chafer beetle (Prodontria lewisi) is a large flightless beetle that lives underground in the sandy soils of the Cromwell river terrace. In spring and summer adult beetles emerge from the ground at night to feed on plants and to breed.

The smell of success: insect pests avoid boosted pasture grasses

A  study from the Bio-Protection Research Centre has shown for the first time that pasture grasses containing beneficial microorganisms are less attractive to soil-dwelling insect pests.

Most New Zealand ryegrass and fescue pastures contain beneficial microorganisms that live within the grass shoots. These fungal endophytes are key to the country’s healthy grasslands. In return for food and shelter the endophyte can help its host grass resist insect attack, survive droughts, and even protect against overgrazing.

Insect pests are attracted to plants by odour as they can smell minute amounts of chemical compounds that tell them if a plant is damaged or healthy.

Food-for-health Challenge scientists will aim to boost NZ exports

The University of Auckland, Massey University and University of Otago, along with Crown Research Institutes AgResearch and Plant & Food Research, are being teamed up for the Government’s High-Value Nutrition National Science Challenge.

The task for the scientists from the five institutions – with other collaborators – is to produce cutting-edge, multi-disciplinary research to help New Zealand companies take advantage of global demand for foods with health benefits.

The ten year challenge is approved with $30.6 million subject to finalisation of contract conditions.

A review at the end of five years means another $53.2 million becomes available for a second five-year period.

Total funding for the High-Value Nutrition Challenge is up to $180.8 million over ten years.

Genome researchers discover how onions recognise when to bulb

Research findings from Plant & Food Research and the University of Otago will help to breed new onions tailored to grow in specific conditions.

Onions, the third largest vegetable crop in the world, form a bulb in response to lengthening days, but the molecular mechanisms controlling this response were not previously known.

The research has identified the gene controlling bulb development, the first step in discovering genetic markers that can be used as tools to screen conventional breeding programmes for new onion varieties with the right genetic profile.

The research is published in the online journal Nature Communications with related research published in Theoretical and Applied Genetics.

“This research is an excellent example of how new genome technologies can enable major discoveries that, in the past, have been difficult,” says Associate Professor Richard Macknight.

“By understanding how these plants control development of the bulb, we can support the breeding of new cultivars that have the right genetic profile to respond to specific growing conditions, ensuring each plant produces a bulb for sale on the market.”

“Commercial production of onions relies on cultivars tailored to the environment they are grow in, responding to the right combination of day length and temperature to form a bulb,” says John McCallum of Plant & Food Research.

“Around 90 million tonnes of onions are produced globally each year, but genetic studies of onions have been limited. Our research is now beginning to link genetics and physiology of onions, allowing industry to tap into more diverse genetic resources and breed products adapted to different and changing environments.”

Onion is the second largest vegetable crop in New Zealand, with 586,000 tonnes produced each year and generating $62 million in export revenues.

The research was funded by the Ministry of Business, Innovation and Employment and supported by FruitFed Supplies, Allium Solutions and Enza Zaden Ltd.