And the colours fade to grey: What is coral bleaching?

By Stephan Kamrad

Hermatypic corals may look like lifeless rocks but they are really living creatures which belong to the animal phylum Cnidaria, together with jellyfish and sea anemones. Many members of the Cnidaria have tentacles equipped with specialised stinging cells that contain venom. These are used for self-defence and to prey on small fish and crustaceans. Hermatypic corals, however, have no stinging cells; they defend themselves with a rock-like, calcareous exoskeleton that is slowly deposited over years. Nor are they predators, instead they live in association with photosynthetic plankton from the genus Symbiodinium, often called zooxanthellae, and the photosynthetic pigments of these unicellular algae give corals their bright colours! Members of the Symbiodinium belong to the Dinoflagellates, a group only very distantly related to land plants and green algae. They are endosymbiotic, meaning they are completely engulfed by the coral’s plasma membrane and live inside their cells. The coral provides the algae with a protected environment and a number of nutrients, like ammonium and phosphate, which it filters out of the water. In return, the Dinoflagellates fix CO2 dissolved in the water to provide the coral with sugar.


Bleached coral (credit Acropora)

Coral reefs are found in tropical oceans, usually only few kilometres off the coast or on sand banks where the ocean is still shallow enough for light to reach the photosynthetic corals at the ground. They are globally rare, covering only about 0.1% of ocean surface but are the habitat of over a quarter of all known marine species! Their incredible biodiversity make coral reefs a valuable resource. Millions of people depend on the reefs as rich fishing grounds. Additionally, reefs physically protect the coastline form incoming waves and prevent erosion. The great reefs of Australia, Florida and the Caribbean yearly attract hundreds of thousands of tourists. When considering their social and economic importance, ecologists speak of ‘ecosystem services’ provided by coral reefs and it turns out their monetary value is immense!

It is thus very concerning that we have seen an immense decline of coral reefs over the last decades. The Caribbean for example has suffered an 80% loss of their coral populations over the last thirty years! The underlying phenomenon known as coral bleaching is a process during which the usually so beautifully coloured corals expel their symbiotic algae causing them to turn white and die. The picture shows a bleached, white coral in the foreground and a healthy coral in the background. Coral bleaching is associated with high peak water temperatures and increasing water acidity, both of which are a direct consequence of rising CO2 levels in the atmosphere.

A group from the University of Georgia recently published new detailed insights into the bleaching process. The research team was able to observe a bleaching event as it was happening at a reef off the coast of Mexico. Their key findings, published in the Journal of Limnology and Oceanography, shows how coral/algae populations can adapt to changes and sometimes even recover from bleaching events. There are many different species of endosymbiotic Dinoflagellates, classified into 9 major clades, and it turns out some of them are more resistant to high temperatures than others. Single corals often host three different algae species at once and their relative abundance determines the temperature tolerance. Furthermore, bleached corals do not die immediately; they can be repopulated and their new composition of Dinoflagellate species is significantly different to their pre-bleached one.

The symbiotic relationship between corals and Symbiodinium is an active area of research. The hope is that through a deepened understanding, we might find ways to protect reefs from bleaching and dying.

Reference: Dustin W. Kemp et al. (2014) Community dynamics and physiology of Symbiodinium spp. before, during, and after a coral bleaching event. Limnol. Oceanogr., 59(3), 2014, 788-797 DOI: 10.4319/lo.2014.59.3.0788

Fluffy Horror

By Nathan Smith

As a general rule, the fluffier a pet is the better. Fluffy things are cuter, more cuddly, and funnier when they move; it’s a win-all situation. But like all general rules, there are always exceptions. In this case the exception is fish.

Fish, as many will have already noticed, are not usually fluffy. Indeed it would be reasonable to put forward the hypothesis that fish and fluffiness are mutually exclusive and, for healthy fish, this is certainly the case. Unfortunately fish cannot always be healthy and sometimes unhealthy fish go fluffy.

Not a happy fish (credit Émilie Proulx)

Not a happy fish (credit Émilie Proulx)

The cause of such fluffiness is an oomycete, or water mould; a type of organism which looks like a fungus but is closely related to kelp. Specifically, it is caused by the oomycete Saprolegnia parasitica, which infects freshwater fish. S. parasitica causes grey/white cotton wool like patches on the skin and gills of infected fish and can coat up to 80% of the host’s body. These patches are external signs of destruction of the host’s skin and underlying tissue and this result in lethargy of the host, making it more susceptible to predation. If the host avoids predation, symptoms of late stage infection are impaired osmoregulation, which is caused by increased haemodilution due to the large scale surface wounds. This is followed by respiratory failure, caused by the extensive infection of the gills. Organ failure is the final result. A closely related species, S. diclina, also infects fish eggs.

Despite the bizarre symptoms, infection by Saprolegnia is no niche occurrence. Whilst it is generally not an issue for wild fish, generally only infecting wounded or otherwise immunocompromised individuals, it is a considerable problem in aquaculture hatcheries and farms, due in part to the overly high densities in which fish are kept. In these environments, losses of more than 10 % due to Saprolegnia are commonplace and as high as 50% in some more extreme cases. Furthermore, it has a significant economic impact, with conservative estimates putting the losses due to Saprolegnia infection at five million pounds per year in Scotland alone.

That Saprolegnia infection is so endemic in aquaculture indicates generally low health in the fish population and highlights issues within the industry. Fluffy fish may not be cute but they can’t be ignored.

Packaging: Is there mushroom for change?

By Sophie Harrington

It’s nearly Christmas and nowadays that seems to mean lots of online shopping. There’s nothing quite so convenient as avoiding the crowds, anxiety, and Christmas music on loop in favour of leisurely browsing from the comfort of your couch. For the most part, deliveries these days are highly reliable, even when you’ve ordered something that doesn’t do well with rough handling—perhaps a new set of glasses, or a bottle of champagne. It’s thanks to the use of packing materials such as polystyrene that we can even consider ordering such fragile items online.

A new use for corn stalks? (Credit Phoebe Baker)

A new use for corn stalks? (Credit Phoebe Baker)

Yet despite their convenience, there are a whole host of environmental concerns that come with traditional packing materials. Most people have heard that this sort of packaging never breaks down, and while that isn’t strictly true, polystyrene discarded in landfills, or left as litter will not degrade for hundreds of years. Our love for packing peanuts and Styrofoam has left us with a mass of polystyrene clogging up our landfills and environment.

But what if there was a better option? Enter mushroom materials, the brainchild of Ecovative. As an alternative to the petroleum-based polystyrene that forms a majority of the packing market, mushroom materials use only natural agricultural waste, such as cornstalks, and mycelium, or the “roots” of fungi. The agricultural waste is placed into a specific mould, through which the mycelium are able to grow, turning the material into a solid block. After growth is completed, the material is fully sterilised before being shipped out to their growing base of customers.

The use of agricultural waste in producing the blocks is only the beginning of their environmental benefits. Not only is this a use for otherwise discarded waste products from farming, but the products themselves are fully compostable at home. No need for expensive processing or complicated techniques to degrade the blocks—just break them up and leave in your garden.

Not just good for eating (Credit Christine Majul)

Not just good for eating (Credit Christine Majul)

Besides the obvious market in packaging materials, Ecovative are branching out into other areas, including furniture and even surfboards! There materials are perfect as light-weight foam cores and fins for surfboards, with the added benefit of being entirely degradable in a marine environment if the board is lost. The materials are also being developed for use as structural biocomposites, using “Myco Foam” that has been heat and pressure treated to compress into “Myco Board” for use in furniture that has no need for the addition of resin (and thus the use of formaldehyde), unlike traditional wood composites such as MDF. Who knew fungi could be so much fun?

Intrigued? Wish you could get involved in the “mushroom age”? Turns out you can even grow your own mushroom materials via the “Grow It Yourself” kit available from Ecovative. This might just make Christmas shopping even easier…

Thar She Blows: of Saharan Dust and Marine Productivity

By Charlie Whittaker

The Sahara Desert is not something you would usually associate with abundant life and vibrant algal blooms. It is one of the most arid and inhospitable areas in the world, representing the largest subtropical hot desert on the planet. And at well over 9,400,000 square kilometres- i.e. about the size of the United States, it is perhaps one of the most inhospitable areas globally. To say that it is unwelcoming to life is an understatement of epic proportions.

The Sahara Desert (credit mtsrs)

The Sahara Desert (credit mtsrs)

However, the desert is in fact one of the cornerstones of continued survival of one of the most abundant groups of organisms on the planet: the phytoplankton. This vast swathe of barren land is actually responsible for a dazzlingly complex and diverse ecosystem albeit thousands of miles away.

Tiny flecks of sand, red in colour due to the abundance of the element iron, are picked up the winds floating across the sand dunes, and in turn, carried thousands of miles westwards on the air currents. These tiny grains of iron rich sand then land in the ocean off the West coast of Africa, where they are responsible for sustaining a astounding array of life. Though individually insignificant and of little relevance, the sheer scale of their deposition makes them a globally relevant input- it is estimated that something in the region of 1015g/year get deposited courtesy of these Saharan winds Westwards. That’s 1012kg, or 1 billion tonnes!

A phytoplankton bloom in the Southern Ocean (credit ESA)

A phytoplankton bloom in the Southern Ocean (credit ESA)

But why all the fuss about iron though? Iron represents a fundamental micronutrient required as a cofactor for the enzymes of a ubiquitous number of different phytoplankton, from cyanobacteria to coccolithophores and diatoms to dizaotrophs. In particular, iron acts as an essential constituent of the enzyme nitrogenase, responsible for the fixation of atmospheric nitrogen. The photosynthetic organisms present in this group are globally significant in terms of the fixation of carbon dioxide from the atmosphere. These so called “forests of the ocean” contribute as much to the control of CO2 levels as tropical rainforests.

Given their dependence on iron then, there has been considerable interest in the concept of “iron seeding” the oceans as a means of generating blooms of these photosynthetic organisms. Such a sudden population rise would lead to increased CO2 drawdown and may have the potential to mitigate, at least in part, some of the consequences of continual anthropogenic mediated CO2 release into the atmosphere. Efforts doing this are still in progress but who would have thought the Sahara Desert, byword for desolate, bleak and lifeless, may have acted as the inspiration for one of the most ambitious biogeoengineering projects currently underway.

Deforestation- whatever that is

By Anna Klucnika

Society is slowly forgetting about deforestation.

That’s not in the sense that we forget it’s happening, but rather forgetting to care. I am one of the few who consciously try to recycle, to use less paper, to switch off lights. My family only recycles because otherwise the normal bin will overflow. My roommate has commented that environmental issues have been made up, as it’s “convenient” to allows us Westerners to stop development in other parts of the world.

The Bornean Rainforest  - how long will it last?

The Bornean Rainforest – how long will it last?

Even Rhett Butler, the man who founded a website that tracks global deforestation and has “devoted tens of thousands of hours to the cause of protecting forests” is not promoting a change in society’s attitude. He unwittingly commented that “lately – for the first time, really – I’ve started seeing cause for optimism about the future of forests”. This was gloriously picked up by the Independent in an article titled “Rainforests ‘out of danger’ thanks to global giants”.

This is like thinking world peace will work out next year.

Now clearly Mr Butler did not mean his words to seem that all of the world’s deforestation issues are resolved. I’m also delighted to hear Sally Uren, head of the sustainable development charity Forum for the Future, say “there is a much greater sense of shared responsibility and I am feeling reassured by the seriousness with which many big multinationals are taking this responsibility”.

But these are just words and many people will jump for joy that they can jump off the eco-friendly bandwagon.

Visiting the rainforest of Malaysian Borneo has made the issue or tropical forest conservation real to me. Driving into the heart of the land you see the town turn into jungle. Then once you get into the core primary rainforest, you realize what you thought was jungle earlier is just the left-over bones. The growing demand of palm oil (have a look at most labels and you’ll find it, probably mixed in with “vegetable oils”) has lead to dramatic fragmentation.

The new forests: Oil Palm plantation

The new forests: Oil Palm plantation

Fresh research by Benny Yeong has revealed that rainforest fragments below a certain size do not yield viable seedlings. This means that the forest will not regenerate. With an increasing proportion of the world’s forests being restricted into national parks, funded by ecotourism, this is a bad omen. Humans must intervene to help sustain forests. Conservation is no longer about stopping deforestation and conversion of land. It’s too late for that. Instead what precious forest we have left must be managed.

But with attitudes concentrating on tree hugging to prevent logging, society’s’ interest is fading. Instead there must be a new green revolution. Just as we try to prevent animal population declines and manage the populations of nearly-extinct species, we must do the same for forests.

Just go into your local bit of woodland and just experience the sense of awe. The sensation that a forest can provide is just as wonderful as that awe of watching wild animals. Forests are an evolutionary masterpiece of conquests, coalitions, and competitions. Since mankind has had such an impact on the Earth, we can no longer rely on the environment sorting itself out. Intervention is needed in a structured and positive manner. Some people are thinking in this way and making plans. But that does not mean that the cause should be abandoned. We must fight on for our forests.

Photos by Anna Klucnika

The Green Killers: Poisonous Plants in History

By Liam Elliott


‘My heart aches, and a drowsy numbness pains

My sense, as though of hemlock I had drunk’

                                                               John Keats


The word poisoning conjures up, to many imaginations, images of deadly dinner parties straight from an Agatha Christie novel or a world of cold war espionage. Whilst these depictions are perfectly justifiable, they often relied on the variety of deadly inorganic or synthetic poisons. Look further back into history, however, and there emerges the use of naturally occurring plant poisons, entwined with some of the most classical and romantic of legends. Scientifically, toxic compounds that may be found in plants often originate as secondary metabolites of which over 100,000 are known.

Secondary metabolites are, by definition, generally not considered to be essential for plant life and are derived from the smaller pool of primary metabolites. Some of these compounds we use every day including caffeine and theobromine whilst others, hopefully in less frequent usage, include cocaine and morphine. Some plants produce highly toxic secondary metabolites however and the historical use of some of these to silence an unwanted voice, or as forms of execution, is well documented

Let’s have a look at some of the most notorious poisonous plants and their history.


Atropa belladonna: Deadly Nightshade

Belladonna’s attractive berries and flowers have helped to entrain its place in mythology.

Belladonna’s attractive berries and flowers have helped to entrain its place in mythology.

Perhaps one of the best known poisonous plants and commonly known as belladonna (literally: beautiful woman), this plant produces a variety of poisonous alkaloids including atropine and hyoscine. The plant is a member of the Solanaceae family which also includes potatoes. Belladonna’s attractive berries are very poisonous and it is therefore somewhat ironic that the plant has a long history of medicinal and cosmetic use. Macbeth of Scotland, immortalized by Shakespeare, is said to have used the plant to poison an invading English army.

Aconitum: Monkshood

Also known as wolf’s bane and devil’s helmet, plants of this genus synthesise toxic aconitine via the terpenoid synthesis pathway. Aconitine is a neurotoxin which targets sodium channels in mammalian neurons. The striking flowers of these plants resemble the hooded clothing of monks and whilst their natural distribution is largely restricted to mountainous regions of the northern hemisphere they are reasonably common features in gardens. Nazi Germany is known to have used bullets coated in aconitum during WWII.

Abrus precatorius

Abrus precatorius berries as recently seen by some enthralled Part II students.

Abrus precatorius berries as recently seen by some enthralled Part II students.

A legume which produces the protein toxin abrin. This is similar to the infamous poison ricin, only around upwards of 70 times as toxic making it perhaps the most potent of plant poisons. The abrin produced is mainly confined to the seeds and the ingestion of a single one may be fatal to an adult human (whilst around 7 ingested berries of the legendary belladonna provide a fatal dose). Traditionally used to make jewelry in areas of South America, aphrodisiacs have also been historically produced from the plant.

Conium maculatum: Poison Hemlock

Native to the Mediterranean, the alkaloids produced by hemlock target neuromuscular junctions and can cause eventual respiratory paralysis and an unpleasant death. The famous Greek philosopher Socrates was sentenced to be executed in 399BC by drinking an infusion of hemlock. It has also been suggested that, in contradiction to traditional beliefs, that the final pharaoh of Egypt, Cleopatra, killed herself by drinking a hemlock-based poison. On the Greek island of Kea, where euthanasia was a societal norm in ancient times, the elderly are said to have drank hemlock infusion once they passed a certain age.

Plant toxins, and their often medicinal potential, give an example of the key place of plant sciences within society. Moreover, a basic level of plant biochemistry and history can give a fascinating insight into the way plants have shaped humanity.

The Future is No Clockwork Orange

By Nathan Smith

Imagine a life without citrus. No glass of orange juice in the morning. No slice of lemon for your iced tea. No having to segregate the green jelly babies because no one honestly likes them and you don’t understand why they continue to be produced. It would be a very different world indeed, but perhaps one we need to start considering.

Credit Father.Jack

Down with the green jelly babies… (Credit Father.Jack)

The threat to our favourite sources of Vitamin C comes from the double-pronged assault of the bacterial diseases citrus canker and huanglongbing (or citrus greening disease), which are currently having a massive impact on the citrus industry. To make matters worse there are few signs of resistance among the plants. This is mainly because the majority of citrus fruits aren’t natural species, they’re cultivars which are the result of varying inter-specific crosses. A few examples are the sweet orange, which is the result of a cross between a male mandarin and a female pomelo; and the grapefruit which is the result of a cross between a male sweet orange and a female pomelo.


The invincible kumquat (Credit Acongagua)

A study by a group from Pakistan tested how various citrus cultivars responded to the citrus canker disease and found that some are more susceptible (like Valencia Oranges) than others (like Pigmented Oranges). While two cultivars were identified as highly resistant, Tahiti Lime and Kozan Sweet Oranges, all the cultivars showed some levels of disease. Unfortunately this indicates that all would eventually succumb to the ravages of citrus canker. That is, all except for the kumquats!  Both cultivars of kumquat tested (Meiwa and Naghmi) lacked the canker-caused lesions that unfairly graced the other plants. This may be because kumquats are only citrus fruits in the loosest sense. Unlike most of these other fruits, which belong to the Citrus genus or are products of genetic crosses within the genus, kumquats belong to the genus Fortunella. This makes them distinctly different to oranges and lemons genetically and means they may be a non-host for citrus canker and perhaps by extension for other diseases plaguing citrus; though reports of a huanglongbing-type disease in Kumquats in Taiwan suggests otherwise.

Even so resistance to citrus canker is promising. Humanity may learn to adapt and a future without oranges certainly seems brighter with the potential for Kumquat Flavoured Jelly Babies. At the very least they might taste better than the green ones.



The Impossible Cheeseburger

By Stephan Kamrad

I have previously written about Just Mayo, a vegan mayonnaise that contains “pea proteins” instead of egg yolk. Another start-up company founded by Patrick Brown, Professor of Biochemistry at Stanford University, makes not only the condiment but the entire burger vegan. Their Impossible Cheeseburger is made entirely from plants and imitates beef in taste, texture and appearance almost perfectly (according to tasters).

Medicago italica root nodules

Medicago italica root nodules

Just imagine a perfectly grilled burger: Juicy and just a tiny bit bloody in the middle. The molecule responsible for the characteristic red colour and distinct, slightly metallic taste is a complex molecule called haem. Haem contains a co-ordinated iron ion and is part of haemoglobin, the protein that transports oxygen in our red blood cells.

The Impossible Cheeseburger gets its haem not from the blood of kettle but from a plant of the legume family (which includes beans, peas and peanuts). These naturally produce leghaemoglobin which is functionally and structurally akin to mammalian haemoglobin. It is red in colour, also contains the haem co-factor and apparently makes a fake burger just as bloody as real beef.

Legumes live in symbiosis with Rhizobia bacteria that populate specially formed nodules in the roots. Those bacteria convert atmospheric nitrogen (N2) to ammonium (NH4+) which the plant is then able to use for growth and development. In exchange, the bacteria are supplied with sugars. Nitrogenase, the bacterial enzyme that fixes N2, is sensitive to oxygen and it is thus important that oxygen levels in the nodule are as low as possible while still being high enough for the bacteria to live. And this is where leghaemoglobing comes in: It is present at high levels in root nodules and buffers oxygen at a constant but low level. All that the scientists at ‘Impossible Food’ had to do was to harvest root nodules and extract the haem (which was probably a lot harder than it sounds).

Whatever your reason to eat vegan is (and there are plenty), there is an emerging industry that will allow you to do so without changing your actual eating habits or losing flavour. While this is potentially a great thing for the customer and the planet, it is important to realise that this product –while being vegan- is in no way natural. It was born in the lab, created not only by chefs but also by biochemists who miraculously turn vegetables into meat. The “Recipe” and exact ingredients remain (just like in the case of Just Mayo) the company’s secret which makes it increasingly difficult for us as consumers to know what exactly we are eating.

The Impossible Cheeseburger will not be available in stores for another few months. If you can’t wait that long, check out this vegan burger recipe based on carrot, kidney beans and cumin.


Eragrostis tef: About orphan crops, spill-overs and a gluten-free alternative

By Stephan Kamrad

In my last article I discussed why our diets are based on so few plant species. Wheat, rice, potatoes and maize are the major carbohydrate sources for almost the entire planet. This makes it all the more exciting when a new player enters the game or at least gets due recognition.

Eragrostis tef (commonly known as tef) is a grass that produces an extremely small seed (less than one millimetre in diameter). It is rich in iron and calcium and gluten-free which makes it suitable for people with celiac disease. It contains over 10% protein and is, unlike other cereals, rich in the essential amino acid lysine.
Tef is not a new cereal crop, it has been grown in the Horn of Africa for at least 3000 years and still makes up a quarter of Ethiopia’s carbohydrate production where tef flour is used to bake the traditional injera flatbread. In modern tef farming, it serves as both an orphan crop in Ethiopia and Eritrea and as a fodder crop and gluten-free cereal in the “Western World”.

Eragrotis tef (credit Rasbak)

Eragrotis tef (credit Rasbak)

Orphan crop is a term used for minor crops that are produced at much lower quantities than the big players and are not traded on international markets. However, they can be of great importance as part of the local culinary and agricultural tradition. They are also commonly well adapted to their specific habitats: Tef, for example, is resistant to many pests and pathogens as well as to drought and excess water. Sadly, orphan crops have been receiving almost no attention from crop improvement and breeding programmes. Advanced techniques like marker-assisted selection or the molecular tools to engineer these organisms genetically have simply not been developed/adapted for these plants. In Africa, orphan crops are especially common which means that our current efforts to improve food security partly miss exactly those who suffer most from hunger and poverty. Aiming to address this, a group of Swiss researchers have founded the Tef Improvement Project and recently published the genome of Eragrostis tef which will massively facilitate future breeding efforts. With help of the genomic sequence, many insights obtained from research on the model plant Arabidopsis and other major crop plants can probably be applied to tef. These “spill-overs” only require relatively small investments but have the potential to impact positively on the life of many millions.

Tef’s exceptional nutritional profile also attracted the attention of western consumers, especially since David William’s bestseller Wheat Belly convinced many Americans that a gluten-free diet is healthier even for people not suffering from celiac disease (for which there is no convincing evidence at all). Since the 1980s, tef has been grown in Idaho, US by a group of farmers around Wayne Carlson who brought the idea of growing tef back from Ethiopia. Due to increasing demands, tef production is rising and the flour is traded internationally with the biggest trader being Prograin International bv based in the Netherlands. Tef is a fast growing C4-grass that can be harvested multiple times within one growing season. High yields and its high protein content make a great fodder for livestock (a luxury that most Ethiopians do not have) and it is now grown in many of the warmer parts of the US as hay and forage crop.

Long ignored by international science and economics, tef couldn’t keep up with the intensively bred and fertilised major crop plants. Now that its importance for the people in its indigenous habitat and its potential for the “Western World” have been noticed, Ethiopian food security has a chance to improve in an effective and sustainable way and Eragrostis tef might turn out to be a valuable addition to our repertoire of crop plants.

 Interested and want to read more? Check out these papers about orphan crops and the TEF genome project.

Citizen Science in Botany: An Interview with Oliver Ellingham

By Nathan Smith

As we entrench ourselves firmly into the computational age, science is increasingly looking towards the general public for help with research. With the world just a click away, games and surveys have become common tools for engaging with the non-scientific community. Indeed, citizen science (as it is more formally known), has become a popular throughout all areas of science, including botany, and looks set to stay as a rewarding area for research in many disciplines. With this in mind, I interviewed Oliver Ellingham, a PhD student from the University of Reading, who has incorporated citizen science into his research of powdery mildew fungi.

What is the research you’re doing?

My PhD project at the University of Reading aims to develop molecular markers to aid in accurate and efficient identification of the approximate 800 powdery mildew species. When applying for funding, most research projects tend to include ‘avenues to impact’. However these are rarely followed through on. To achieve this small element in my project I have started the ‘Powdery Mildew Survey’: a citizen science scheme aiming to increase public knowledge and awareness in my research topic, but also biology, pathology, and horticulture in general. 

What is powdery mildew and why is research into it important?


Powdery mildew on an oak leaf (credit Oliver Ellingham)

Powdery mildew is a fungal plant disease. It is termed ‘biotrophic’, meaning that is relies upon its plant host to live, survive, reproduce, and thrive. It will therefore not kill the plant, but greatly reduce its vigour, beauty, and fruit production.There are currently many research projects into varying aspects of this fungus, concerning disease spread and management (using both biological and chemical controls), as well as, like mine, ways to differentiate between the many species using varying parts of its DNA.This is important as being able to tell the difference between different species enables us to track them and know which are new to our island and which have always been here. In this way we can help to limit spread of pathogens between geographically separate areas.


What is the economic impact of powdery mildew?

Powdery mildew costs global agricultural industries millions of pounds per year in control and/or reduction in crop yields. As examples, up to 100% of a grape crop and 20% of a pepper or tomato crop can be lost if left untreated with fungicides.

Less precise figures are available in the horticultural industry, however there have been interesting developments in grand-scale flower production. Roses produced en masse in the Netherlands are treated with fungicides to prevent distortion of the flower via powdery mildew infection. However in recent years, large-scale growers have turned to a new, significantly more expensive, biological control: the plants are treated with another fungus, called Pseudozyma flocculosa. This is antagonistic to the powdery mildew, and strangles it, but not the plant.

What does the citizen science scheme entail?

I offer an identification service. Members of the public can send me their powdery mildew infected plant material, and by identifying the host plant, analysing the fungus’ microscopic, morphological features, and finally extracting and amplifying its DNA I can identify the single species of powdery mildew present. As a by-product of this the sampling number for my project is greatly improved, as well as the distribution and diversity.


What struggles have you had getting the public engaged in the scheme?

The hardest thing in this first year of the project has been spreading awareness. I believe this to be significantly easier in the present-day, due to the internet and social media. However contacting like-minded, enthusiastic people, willing to spread the word is difficult when just sitting at my computer. Networking at flower shows and various conferences has helped this hugely, and I am very grateful to the people who have showed an interest and shared contacts with me.


What do the initial results from you research show?

Firstly, that powdery mildew is extremely common in the UK and that identification of its presence is possible by anyone. Also, that species identification is possible using microscopic, morphological analysis combined with molecular data. It has also shown that certain species are more common than others: those of the Erysipheae tribe, which have been shown to possess certain proteins to increase their ability to adapt and infect new hosts, are most abundant; while Phyllactineae are less common, potentially due to the adaptation of many of their features to warmer, Mediterranean climates.

For more information on Oliver Ellingham’s research and to get involved in the citizen science scheme, please visit his blog at or follow him on Twitter at @PowderyM