Internationally significant research into one of the big unsolved questions of plant science, how plants grow, is taking
place in New Zealand and several overseas scientists are keen to be involved in this research after attending a workshop
run by two HortResearch scientists.
As a result of the workshop six scientists want to come back and work with the HortResearch scientists Peter Minchin and
Michael Thorpe. Dr Minchin and Dr Thorpe have been asked to join a $10m United Kingdom research proposal. A scientist
from Australia and another from Italy are both keen to get started on collaborative work.
The technique of observing growth in a living plant, developed by Dr Minchin and Dr Thorpe, is not available anywhere
else in the world. They measure radioactive carbon-11 (11C) movement within plants to learn more about how the growth of
different plant parts is co-ordinated and how plants respond to different challenges and stresses.
"We are working with 11C to try and explain how plants function or malfunction, and why there is an increase in yield in
some plants," Dr Minchin said. "Understanding plant growth will give us the knowledge for manipulating where the growth
occurs so it can influence yield and size, sweetness or acidity."
Yield is a critical factor in food production. Understanding why some plants produce more than others is one aim of the
programme, for example why apple trees produce more in New Zealand than they do in the northern hemisphere.
Understanding plant growth and plant adaptation to different environments is important to provide information for bigger
and better crops and better tasting produce. More yield, more output, less land use.
The 11C workshop, run at GNS at Gracefield in Lower Hutt, attracted 13 scientists, eight from overseas. The amount of
international interest amazed Dr Minchin and Dr Thorpe, though they admit they were able to "capture" the scientists on
their way to a "very specialised" conference on assimilate transport and partitioning that the two helped to organise in
Australia.
Both physicists by training, Dr Minchin and Dr Thorpe started this work 23 years ago and have developed special analysis
procedures central to this work. They now have some answers and can explain how a change in growth pattern happens, but
don't yet know if it is the only reason.
Because of the rapid decay of the 11C (it has a "half-life" of 20 minutes) it must be used at the site where it is
produced in a particle accelerator at the Institute of Geological and Nuclear Sciences (GNS). Though the two scientists
are based at Ruakura in Hamilton, they make five or six trips a year to Lower Hutt to use the radioactive material with
living plants.
Another aspect of the research is the Biological Accelerator Mass Spectrometry (BAMS) technique for detecting another
form of carbon, carbon-14, in plants at extremely low levels. This has been developed by GNS from a carbon-dating
technique and can measure 14C from tiny samples as small as a single plant cell.
Back at Ruakura the two work on other aspects of plant growth. Dr Minchin works on various kiwifruit projects such as
predicting fruit growth. Dr Thorpe works on apple fruit maturity and ripeness. Another fascinating part of their
research involves using aphids to extract plant sap for analysis.
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