̽��ֱ�� of Cambridge - fungi

‘Smoke detector’ enables fungal partnership that allowed plants to first survive on land

fpjl2 — Fri, 18 Dec 2015 10:56:53 +0000

New research has revealed that a plant protein known to detect growth-promoting compounds in smoke from burning vegetation has a much older and broader role: recognising initial signals sent from the beneficial soil fungi that deliver nutrients directly into plant cells.

By identifying the molecular signals emitted through the soil by friendly fungi, the protein enables a plant to “roll out the red carpet” for cell colonisation by the fungi, and all the survival advantages this mutually-beneficial relationship brings – the fungi feeds minerals such as phosphate into plant cells in return for sugar extraction.

This “symbiosis” between plants and certain microbial fungi is prevalent across the plant kingdom, and thought to date back to the earliest transitions of plant life from water to land some 450 million years ago, as plants had to develop ways of surviving on land by acquiring nutrients from soil many millennia before they evolved roots.

Scientists believe this ancient relationship with fungi was likely critical to the early terrestrial survival of plants, and consequently the evolution of “all higher life on earth”.

While previous research had shown that plants can clearly tell the difference between beneficial fungi and those that offer nothing or cause disease, how they make the distinction had proved mysterious. Now, latest research has unravelled the genetic code of the plant protein that enables the “cross-kingdom dialogue” between plants and fungi – allowing plants to let the right fungi in.

Surprisingly, the protein is an enzyme known to science as the receptor for Karrikin, a plant hormone created when vegetation is burned. Karrikin – from karrik, the Aboriginal word for fire – triggers seed germination in certain species of plant known as “fire-chasers”: plants that are first to sprout once wildfires have devastated their competitors.

While only those few fire-following species such as eucalyptus and some members of the tobacco family use the protein (called D14L) to “tune into smoke signals”, the latest study shows that this same protein is used by the vast majority of plant life on Earth to tune into fungi – perceiving the molecular signals from friendly fungi, and enabling a relationship that helped sustain plant life on land hundreds of millions of years before the evolution of roots and seeds.

“This protein had already been seen to detect smoke hormones in a few fire-chasing plant species, but now we’ve shown it’s the same protein that is central to the everyday interaction of plants with beneficial fungi. This primary, ancestral role of forging a symbiosis with fungi is harnessed by over 80% of all plant species on the planet,” said Dr Uta Paszkowski, from Cambridge ̽��ֱ��’s Department of Plant Science, senior author of the study published today in the journal Science.

“Such fungal symbioses assisted plants to make the transition to land. We are beginning to unlock a process which is taking us back to the first stages of plant life on land some 450 million years ago, one of the key evolutionary steps of life on planet Earth,” she said.

For the new study, scientists found the first “mutant” rice plant that had no susceptibility at all to the friendly fungi. ̽��ֱ��team was able to work out the missing gene, and isolated the D14L protein as the critical element for the detection of these fungi in plants.

“Fungi and plants secrete all sorts of molecules, like a dialogue through the soil, and what we captured is the ‘hearing’ side in plants. Removal of the protein renders the plant insensitive to the fungus – in other words, the plant has become deaf,” said Paszkowski.

When colonising a plant, the beneficial fungus blooms within individual plant cells, growing thin tendrils called hyphae that extend into surrounding soil and pump minerals and nutrients straight into the heart of plant cells. Plants colonised by friendly fungi get between 70 to 100% of their phosphate directly from these hyphae, for example. In return, the fungus gets its sugars from the plant.

Plants monitor their surrounding for the presence of other bacterial or fungal invaders normally using ‘receptor-kinases’. “We and others had assumed the protein mechanism plants use for identifying beneficial fungi would be related to those,” said Paszkowski.

She describes it as a “real surprise” to find the D14L protein, a ‘hydrolase’ protein which functions deep inside the cell, to be necessary for the communication with the friendly fungi.

As the D14L protein is also involved in plants developmental responses to light Paszkowski talks of a “gut feeling” that – with this ancient protein responding to light, atmosphere (through smoke detection) and soil environment (through fungal symbiosis) – it could have been a developmental crossroads vital to plants’ evolutionary leap out of the oceans.

“Light; atmosphere; soil: all aspects crucially different when making that change from water to land, and all adaptations that would be influenced by this one protein. ̽��ֱ��D14L protein may take us back to the earliest days of life on land,” she said.

A protein that detects hormones in smoke has a much wider and more ancient role in the plant kingdom – detecting microscopic soil fungi which colonise plants and feed nutrients to their cells. This ancient symbiosis with soil fungi is thought to be how plants survived on land millions of years before they evolved roots.

Fungi and plants secrete all sorts of molecules, like a dialogue through the soil, and what we captured is the ‘hearing’ side in plants

Uta Paszkowski

Paszkowski lab

This microscopic image shows the spores and hyphae of 'friendly' arbuscular mycorrhizal fungus interacting with a plant root.

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Yes

̽��ֱ��‘flying scientist’ who chased spores

lw355 — Wed, 11 Feb 2015 09:00:34 +0000

On a July day in 1930, British Airship R100 took to the sky from a Bedfordshire airfield on its first transatlantic flight. As it made its way across the Atlantic Ocean, 2,000ft above sea-level, a window opened and Squadron Leader Booth, wearing a pair of rubber gloves, leaned out. In his hand was a Petri dish.

Below, on the HMS Ausonia, Cambridge mycologist Dr W.A.R. Dillon Weston watched through the porthole of his cabin. It was his Petri dish – in reality, a spore trap, capturing minute particles released from fungi and carried with the wind – that Booth was holding. “ ̽��ֱ��thrill of the airship excited Dillon Weston as much as the thrill of spore chasing,” explained Dr Ruth Horry from the Department of History and Philosophy of Science, who has been researching his story.

This adventure was set against the backdrop of what Picture Post magazine declared a “man-versus-fungi battle”. Wheat rust had wiped out enormous areas of American and Canadian wheat production and coffee rust had destroyed entire plantations in Ceylon. “Those who know most about them are still frightened of the fungi,” said Picture Post.

Dillon Weston and fellow scientists suspected that one route of spore transmission over long distances was through air currents. But how to test this? “He was carrying out his studies in the 1920s and 1930s when research methodology was in its infancy,” said Horry. “Where his creativity literally took off was in realising that to test the atmosphere for spores he had to invent ways to catch them, using aeroplanes and home-made Vaseline spore traps.”

“At first sight it may appear ludicrous that the aeroplane can have any significance in biologic research. Is it, however, absurd?” said Dillon Weston in 1929. Intrigued by the finding of some of his American colleagues that aircraft-borne spore traps could detect spores at 11,000 feet, Dillon Weston persuaded friends in the Cambridge ̽��ֱ�� Air Squadron to fly over the Cambridgeshire countryside at various heights. Although his results were as much about devising the perfect spore trap as about the spores themselves, he concluded that the air was a viable medium for spores to be transported.

“Devastating yet invisible plant diseases were an important enemy to conquer and new aviation technologies were vital in winning the war against them,” said Horry. “Newspaper coverage of the time showed that the scientist who chased invisible diseases captured both tiny spores and the imagination of the public: ‘Disease germs two miles up – flying scientists chase them’ declared one newspaper.”

But it was Dillon Weston’s next foray into the skies that is perhaps the most fascinating as a milestone in mycology, and the history of science, as British Airship R100 took off with his spore traps aboard. ̽��ֱ��mycologist had in effect moved his laboratory from the earth into the skies above.

“He watched the airship through the porthole of his cabin, with his spore traps 2,000 ft skywards in the hands of the airship’s Captain,” said Horry. Using official flight papers, telegrams, family letters and newspaper reports, Horry has pieced together not only the events of the day, but also how he managed to ‘piggy-back’ such a high-profile experimental flight with his homemade spore traps.

“ ̽��ֱ��airship project had been foundering through technical setbacks and lack of financial support,” she explained. “Sensing an opportunity, the Air Ministry co-opted Dillon Weston’s spore experiment as a means of adding scientific legitimation to the scheme – it helped to sell an unknown airship to a public suffering from ‘airship fatigue’.”

Dillon Weston’s results from the airship experiment were never published, as it became impossible to repeat this initial trial. Two months after the R100 completed her journey, the British Air Ministry’s airship R101 tragically crashed on its first voyage to India, claiming the lives of all on board. Less than a year after the spore experiment, the airship scheme was terminated.

Although the experiment was never to be repeated, Horry believes that it is representative of a wider concept in science: the idea of ‘piggy-backing’ small-scale experiments on larger scale projects. “Dillon Weston’s scientific work aboard R100 was a small-scale experiment that required complex technologies to reach its location of study,” she said.

“As fascinating as this story of airships and fungi is, its wider value has been in revealing that historians need a better understanding of scientific experiments that are dependent upon large-scale, external technological programmes for their existence.” She points towards astrobiology experiments to study the origins of extraterrestrial life on board early NASA space flights as a more recent example of piggy-back science.

Horry added: “ ̽��ֱ��spore experiment’s subsequent disappearance from view acts as an indicator that other now-forgotten examples of piggyback science could have been attached to large scale 20th-century technologies. It may just require us to don our historical rubber gloves, take to the air and chase them down.”

Inset image – top: Dillon Weston. Credit: John S Murray

Inset image – middle: R100 at mast in Canada. Credit: Ruth Horry

Inset image – bottom: Puffballs - Lycoperdon. Credit: Whipple Museum of the History of Science

A passion for fungi led Cambridge mycologist Dr Dillon Weston to ever-more inventive means of trapping fungal spores, even from the open window of an airship on its maiden flight in the first half of the 20th century.

Newspaper coverage of the time showed that the scientist who chased invisible diseases captured both tiny spores and the imagination of the public

Ruth Horry

̽��ֱ��‘Flying Scientist’ who Chased Spores

Ruth Horry

R100 at mast in Canada

Fungi formed from glass

At the same time as he saw the devastation to crops and financial ruin that fungi could cause, Dr Dillon Weston was mesmerised by their splendour. “People thought fungi repulsive, and I wanted to show how beautiful they can be,” he wrote at the time.

Take Phytophthora infestans, the potato blight pathogen, responsible for destroying potato crops across Europe in the 1840s, contributing to mass starvation and the Great Irish Famine. Dillon Weston used the pathogen as the basis of an intricate glass model the height of a hand’s span, 400-times larger than the actual organism. Its delicate tendrils stretch upwards, crisscrossing each other in a complex and fragile array of strands topped by tiny oval heads crammed with spores. It is beautiful, but this beauty belies the pathogen’s legacy of death.

“He crafted some of his models in microscopic detail, showing fungal processes like spore formation and release,” explained Dr Ruth Horry from the Department of History and Philosophy of Science, who has been researching the life stories of objects that become part of museum collections.

His legacy of over 90 models is now housed in the Whipple Museum of the History of Science in Cambridge. Many are impeccable reproductions in microscopic detail of fungi such as those responsible for the mould commonly seen on bread, the fungus that sweetens wine and the leaf spot found on sugar beet; others are life-sized interpretations of woodland fungi, brightly coloured in russet and ochre; and all would have been an invaluable teaching aid for his students who rarely had access to three-dimensional representations of the organisms they were studying.

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Yes

New database for vital model organism launched

gm349 — Mon, 28 Nov 2011 16:16:10 +0000

A new database promises to be an invaluable resource to scientists who use a unique single-celled fungus to study human diseases.

̽��ֱ��new database for the fission yeast Schizosaccharomyces pombe, called PomBase, was launched today by a consortium of researchers at the ̽��ֱ�� of Cambridge, the European Bioinformatics Institute (EBI), and ̽��ֱ�� College London (UCL).

Fission yeast is a single-celled fungus (yeast). Because their cells function much like our own, and it is an important model for studying cellular processes frequently associated with heritable diseases and cancers.

Scientists have already discovered that fission yeast has equivalents of many human genes which are known causes of rare genetic diseases and syndromes (including Batten', Bloom's, Birt-Hogg-Dube, Liddle, Lowe, Niemann-Pick). Additionally, fission yeast have counterparts of human genes implicated in diseases with multiple causes, to include many cancers, deafness, neurological diseases, heart disease, Parkinson's, and anaemia.

Biologists today are very dependent on computer databases that catalogue the functions of the genes of the organisms they study and give access to other supporting information. ̽��ֱ��PomBase website will therefore prove to be an important tool for researchers studying fission yeast.

Its launch is the first stage of a 5-year project funded by the Wellcome Trust to provide a model organism database that allows researchers around the world to participate directly in the curation process in addition to using automated procedures based on the genetic blueprint of the fission yeast. ̽��ֱ��project uses Ensembl software for genome browsing, which is already used to present data for many other important experimental species. Novel tools and resources generated by this project will also be available to researchers working on other species, including human pathogens, to create similar databases.

Steve Oliver, Professor of Systems Biology & Biochemistry, who is spearheading the initiative, commented: "Organism specific database projects frequently have limited resources, and large backlogs of uncurated literature. An important novel component of this project is the construction of intuitive tools to allow the research community to involve itself in database curation, and ensure that the scientific information published in their papers is visible to the entire biological research community. These tools can also be shared with other groups and implemented for their organism of interest.”

Valerie Wood, PomBase Manager and co-investigator, said: "PomBase is not only establishing a database for this important model, it is also adapting the EBI's Ensembl Genomes platform and constructing tools to allow the research community to curate their own publications. ̽��ֱ��PomBase protocols will enable other research communities to establish and sustain similar databases for other experimental organisms. We have already identified counterparts for over 300 human disease genes in PomBase and many of these are being studied to elucidate the cellular basis of a diverse range of diseases.”

Jurg Bahler, fission yeast researcher and PomBase co-investigator from UCL, added: “Many basic cellular processes are conserved between yeast and humans, and PomBase will used extensively by biological and biomedical researchers world-wide to study mechanisms involved in cell growth and division.”

Paul Kersey, PomBase co-investigator from EBI, said: “PomBase has adapted the EBI's Ensembl platform to provide a multi-faceted resource dedicated to the needs of fission yeast researchers. These developments will enable other research communities to establish and sustain similar databases for their favourite experimental organisms.”

̽��ֱ��community curation initiative for PomBase will be launched in Spring 2012. ̽��ֱ��database can be found at: www.pombase.org

̽��ֱ��database, PomBase, important new tool for scientists researching fission yeast.

An important novel component of this project is the construction of intuitive tools to allow the research community to involve itself in database curation, and ensure that the scientific information published in their papers is visible to the entire biological research community.

Steve Oliver, Professor of Systems Biology & Biochemistry, who is spearheading the initiative

Image UCL

Pombe

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Yes