Research team’s genetic mānuka map scores a first for native NZ species

The mānuka Leptospermum scoparium has become the first New Zealand native tree species to have a high-density linkage map built for it.

The map has been built by researchers from Plant & Food Research, AgResearch and the University of Otago using thousands of genetic markers obtained by sequencing.

Researchers David Chagné, Julie Ryan, Munazza Saeed, Tracey Van Stijn, Rudiger Brauning, Shannon Clarke, Jeanne Jacobs, Philip Wilcox, Emma Boursault, Peter Jaksons, Dan Jones, Amali Thrimawithana, Kathy Schwinn and David Lewis have published their findings in the new special issue of The New Zealand Journal of Crop and Horticultural Science.

Reassessment of plant growth regulator Meteor

Public submissions are open on an application to reassess restrictions on the use of Meteor, a substance used to thin pip fruit.

On November 12 2018 a decision-making committee appointed by the Environmental Protection Authority decided there were grounds for the reassessment because of ‘information showing a significant change of use’.

This is a modified reassessment and is only considering some proposed changes.

The applicant, AgriNova NZ Limited, wants to reduce both the maximum application rate and the restricted entry interval (how long access to the treated area is restricted after spraying). It also proposes that buffer zones may be reduced as a consequence of reduced application rates.

AgriNova has identified no potential adverse effects associated with the proposed changes.

It says the potential benefits are:

• reduced risk to environment due to applying a lesser amount of active substance
• an increase in efficiency and flexibility of crop management and better utilisation of staff
• an enhanced ability to monitor for pests and disease.

The application is being publicly notified to enable people to provide us with additional information they believe we should be aware of, such as positive or negative effects of the proposed changes.

Submissions close at 5pm on May 1.

Details are available on the EPA website.

Source:  Environmental Protection Authority

Global apple and pear breeding programme heats up

New, superior tasting apples and pears that can thrive in the planet’s increasingly warm climate will soon be available to fruit growers worldwide.

T&G Global (formerly Turners & Growers) has joined Plant & Food Research, the Institute of Agriculture and Food Research Technology (IRTA) and Fruit Futur as the exclusive partner for the commercialisation of exciting new apple and pear cultivars, developed in a world-class breeding programme, designed specifically to tackle challenges such as sunburn, colour and firmness associated with a warming global climate.

The Hot Climate Programme (HCP), one of the most exciting global breeding projects, was initiated in 2002 by Plant & Food Research and IRTA to address challenges that were being experienced by Spanish growers, particularly those of the Catalan region, with traditional apple and pear varieties.

Plant & Food almond project expands to three states in Australia

Plant & Food Research Australia’s almond research has expanded to Victoria, New South Wales and South Australia. Once planting is completed this winter there will be 7,105 research trees and 12.3 hectares of trial sites across the three states.

The research, funded by Hort Innovation, aims to double almond yield without increasing costs by optimising almond tree architecture and understanding how different cultivars respond when planted at high density.

Since the research team has established similar trials in California, funded by the Almond Board of California, the projects are now relevant to the two largest almond producers in the world: California and Australia represent 88 per cent of the global supply of the high-value nut crop.

“Our approach is to work with the natural growth habit or tree architecture of specific cultivars and develop minimal ‘low input’ pruning methods to produce trees suitable for commercial high density planting,” says Dr Grant Thorp, Scientist at Plant & Food Research Australia.

‘We want to develop management strategies that are cost-effective, simple to implement and preferably ‘one-off’ at the time of orchard establishment instead of an annual requirement.”

Further benefits will include reduced time for new orchards to produce their first commercial crop, development of tree shapes suitable for ‘shake and catch’ harvesting, and smaller trees for more efficient water use and easier pest and disease management.

The funding statements can be accessed HERE.

Source: Plant and Food Research

 

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

Plants show an unexpected response to more carbon dioxide

Plants are split into broad categories based on how they process carbon. The two main groups are C3 (eg rice, wheat, trees) and C4 (most grasses including corn and sugarcane).

It was thought C3 grasses are more sensitive to carbon dioxide levels and will grow more vigorously under higher CO2 levels. But a new, 20-year study suggests this is only in the short-term:  after 12 years the patterns reversed with C4 ramping up their growth.

A scimex post (HERE) reports that Australian and New Zealand experts say this long-term information is essential to understanding future distribution of plants with increased CO2 in the atmosphere.

A media statement from The American Association for the Advancement
of Science tells us more:

Past research has clearly established that two groups of plants respond differently to elevated carbon dioxide levels, with one group gaining substantially more biomass when carbon dioxide is more abundant; however, a new study monitoring plots over a 20-year period reveals that this well-established pattern is in fact reversed over long time scales.

Scientists categorise plants based on the way in which they process carbon, the two most common classes being C3 (eg, rice, wheat, trees) and C4 (eg, corn, sugarcane, most other grasses). Theory and experimental evidence have suggested that C3 grasses are more sensitive to carbon dioxide levels than C4 species and thus will grow and gain more biomass in response to rising carbon dioxide levels – a pattern that is critical to understand to accurately model future climate.

But, past experiments have only looked at C3 and C4 responses over relatively short periods.

Peter B. Reich et al. now report results from a 20-year study monitoring 88 plots in Minnesota, U.S., which are part of the BioCON project.

They found that, during the first 12 years of the study, C3 plots averaged a 20% increase in total biomass in response to elevated carbon dioxide levels, compared to ambient conditions, while C4 plots averaged a 1% increase, changes that were in line with expectations.

However, during the subsequent eight years, the pattern reversed: C3 plots averaged 2% less than their ambient counterparts, and C4 plots averaged 24% more biomass. The researchers found that variables such as rainfall and net photosynthesis of the plants had little correlation with this reversal, while, mysteriously, the mineralisation of nitrogen did.

Mark Hovenden and Paul Newton provide more context in a related Perspective, illustrating the value of longer-term research in revealing the complexities of ecological patterns. They note that because C4 plant species contribute 25% of land biomass globally, provide an important forage source for grazing animals, and are over-represented among weeds, it is especially important to correctly estimate the future distribution of these plants.

• The research can be found HERE on the AAAS web page.
• Editorial/opinion from the AAAS is HERE. 

Study of sweet potato raises questions about early contact between Polynesia and the Americas

New research challenges the citing of sweet potatoes in Polynesia as evidence of pre-European contact between South America and Polynesia, according to a scimex report (HERE).

Genetic evidence indicates the plant species is at least 800,000 years old — far older than even early humans – and the researchers suggest the sweet potato was dispersed naturally around the Pacific. Hence it was already there when humans arrived.

But New Zealand experts approached by the Science Media Centre question the conclusions of the study and call for more robust evidence.

Scimex quotes from a media release from Cell Press, which draws attention to a paper published in Current Biology (see HERE).

 The evidence in the paper suggests sweet potatoes were growing long before there were any humans around to eat them, Cell Press says.

It also suggests the sweet potato crossed the ocean from America to Polynesia without any help from people.

“Apart from identifying its progenitor, we also discovered that sweet potato originated well before humans, at least 800,000 years ago,” says Robert Scotland from the University of Oxford.

“Therefore, it is likely that the edible root already existed when humans first found this plant.”

Scotland and colleagues set out to clarify the origin and evolution of the sweet potato, which is one of the most widely consumed crops in the world and an important source of vitamin A precursors.

They also aimed to explore a question that has been of interest for centuries: how did the sweet potato, a crop of American origin, come to be widespread in Polynesia by the time Europeans first arrived?