Saturday, December 2, 2023

Getting to the root of pine challenges

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What makes pines thrive in some areas but not others? Scion researchers are part of a multi-country project to answer that question by looking at, and beyond, the trees.
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Whether it is on islands off the coast of Mexico, in the California back country or in New Zealand’s central North Island, the ability of pine trees to survive and thrive is being put under researchers’ microscopes.

Scion scientists, along with researchers from universities in the United States, Australia and Lincoln University, are taking a hard look at what it is beyond the trees themselves that enables them to thrive in some areas while appearing to struggle in others.

Their work involves diving into the trees’ below-ground soil and root microbiome – that collection of fungi, bacteria and micro-organisms that live in and on the tree and its surrounding soil environment. 

For Scion researcher Dr Steve Wakelin and PhD student Sarah Addison, this has included visiting Pinus radiata sites in New Zealand, the US, Australia and Mexico, taking samples of the trees’ soil environment as part of the five-year Tree Root Microbiome project.

“It is really very similar to humans, for trees. We are not just a collection of cells, but have our own microbiome that lives in and on us, a part of us that influences our health, our fitness and our function,” Wakelin says.

The project has spanned the northern and southern hemispheres and currently has samples from 750 pine trees  including 450 from NZ. 

Wakelin says it is often thanks to the goodwill of farmers and landowners that the researchers have been able to get samples from a wide array of pine stands, including individual trees, which has been invaluable in gaining a good variety of microbiome samples.

“And it can be those odd trees or unusual stands that offer the real insights.”

He likens their project to the human microbiome project launched back in 2007, where stage two aimed to better understand the role of microbes in human health and disease. Over its nine years from 2007 to 2016 the project delivered a better understanding of multiple bacteria and their interaction with human health.

Wakelin says the evolutionary window humans have enjoyed of about 3.5 million years pales against the 60-70 million years plants have evolved over, a period that has included some significant seismic upheavals and geological events.

Addison says accompanying the trees and their adaptations over that vast period of time are the microbes that inhabit their environment, but little has been understood or known about them. 

Their ability to adapt to shifts in the environment quicker than the trees themselves can pushes out the trees natural range, and with that their ability to change and withstand changes in their environment bought on by factors like climate change.

With the advent of DNA technology, including high throughput sequencing, it is possible to better understand the unique aspects of the microbiome that accompany the trees, specific to the different locales they have adapted to over that time.

“In areas like Australia, where drought is more common, areas like south and western Australia with light sandy soils, these places can provide glimpses of what it could be like in NZ, how it could look in 50-60 years’ time.” 

In Monterey, California, where pines are endemic, the trees are facing multiple threats from disease, drought and fires that have seedlings struggling to advance in growth due to persistently dry conditions. 

Researchers took soil samples in March from pine locales along the US’s western seaboard, extracting DNA to get a profile of the microbes inhabiting the pines’ below-ground habitat. 

One possible factor also contributing to the pines’ struggle in their native home could be accumulated pathogen loadings over time, something researchers are hoping to better understand as they pick through the microbiome’s composition.

Wakelin says the project, while focused on pine trees, provides a valuable template for better understanding how other trees, both natives and exotics, can adapt and respond to their environment.

“Pines grow fast and can be manipulated, and we have their genomic map so we know them inside out.”

The Tree Root Microbiome Research Programme is jointly funded by the Ministry of Business, Innovation and Employment’s Endeavour Fund and the Forest Growers Levy Trust. It is a partnership between Scion, Western Sydney University, Wright State University, Victoria University of Wellington, Woodwell Climate Research Centre, the Australian Plant Phenomics Facility and Lincoln University.

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