Ancient herbs– magic or medicine?

By Sophie Harrington

Mix together some leek and garlic in a broth of wine and bullocks gall, and what would you get? It sounds like a rather odd kind of soup, but may in fact be an effective treatment of antibiotic-resistant Stapholococcus aureus, or MRSA. Derived from an old Anglo-Saxon recipe, this sounds like an April fools joke, or certainly not something that would be published in a scientific journal. However the history of medicine is littered with examples of traditional herbal remedies that turned out to have scientifically proven effects.

Peacetime in ancient Sumer, as depicted in the Standard of Ur, likely facilitated the creation of lists of medicinal herbs. (photo credit Alma E. Guinness)

Peacetime in ancient Sumer, as depicted in the Standard of Ur, likely facilitated the creation of lists of medicinal herbs. (photo credit Alma E. Guinness)

From the ancient Sumerians, where lists of medicinal herbs including opium and myrrh have been found, through to the herbal knowledge of the Benedictine monks and nuns, humans have long known that many plants have the ability to alleviate symptoms and even cure diseases. Yet today, the idea of “herbal remedies” is often tainted by association with other, less rigorous, forms of alternative therapies with little to no evidence behind them, such as homeopathy.

Our traditional herbal remedies, however, stem from the production of unique compounds in different plants, resulting in a huge variety of potential chemicals that can be, and are, tapped for medical use. These compounds, known as secondary metabolites, can be produced by plants to help defend themselves from herbivores and insect attacks, while others may define the unique scent of a flower.

One group in particular, the alkaloids, have had an immense impact on medicine. Defined by the presence of nitrogen-containing carbon rings, alkaloids include such common substances as caffeine and nicotine. The anti-malarial drug, quinine, is derived from the Cinchona tree. First used by the Quechua in South America, quinine is derived from the back of the Cinchona tree which is dried and powdered before use. Many of us know the bitter flavour of quinine from tonic water, which was used to provide protection against malaria to British officials and colonists in India and other tropical regions. Our tonic water today has much lower levels of quinine, however, so don’t rely on that for protection against malaria!

The anti-inflammatory properties of willow bark are well known, and the source of Aspirin (credit Gareth Williams- Flickr)

The anti-inflammatory properties of willow bark are well known, and the source of Aspirin (credit Gareth Williams- Flickr)

Even more common is aspirin, a go-to for headaches and muscles aches, that has its original medicinal uses dating back as far as the ancient Egyptians. Derived from the bark of willow, it was used to treat fevers and inflammation, just as it is today. Initially obtained through teas brewed from the bark of the willow tree, at the turn of the 20th century the drug company Bayer began marketing a less irritating, synthetic variant known as Aspirin, the drug we know today.

Of course there are some herbal remedies that no longer stand the test of time—many remedies were based on visual similarities, such as dandelion being thought to relieve jaundice due to their shared yellow colour. Yet the importance of natural plant derivatives in both historical and modern day medicines is often overlooked, or misunderstood. Is it that surprising, though, that our ancestors were able to discover which plants had special abilities to alleviate pain or illness? After all, we are an inquisitive bunch!

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Tuberculina/Helicobasidium: A fungal Jekyll and Hyde

By Nathan Smith

Taxonomy can often present itself as fixed fact; a sturdy rock in the uncertain storm of science. However this is not always the case, especially in understudied groups such as fungi. For example, Tuberculina a genus of fungus that parasitizes rust fungi. Rusts, such as Coffee leaf rust, Asian soybean rust, and wheat stem rust, are plant pathogens with major economic impact and Tuberculina was seen as a potential biocontrol agent for their management.

Jekyll and Hyde, or Helicobasidium and Tuberculina?

Jekyll and Hyde, or Helicobasidium and Tuberculina?

Helicobasidium, on the other hand, is responsible for violet root rot, causing root rot, yellowing, and in extreme cases death of the host. It has a wide host range including apple, sugar beet, soybean, potato, cotton, peanuts, tea, plum, grape, and carrot. More than 24% of planted acres of sugar beet in the USA have economic damage caused by violet root rot with the losses being as high as 50%.

It appears then that Tuberculina is a genus that can be used beneficially and should be encouraged in crop fields whereas Helicobasidium should be controlled against and excluded where possible. There’s just one problem: they are the same genus.

These ostensibly separate genera actually represent different stages in the fungal life cycle. Tuberculina and Helicobasidium samples were found to have morphological and genetic similarity. Most importantly, inoculation of a host with Helicobasidium spores was capable of causing a Tuberculina infection.

Wortel_violet_wortelrot_(Helicobasidium_brebissonii_on_Daucus_carota)

Helicobasidium on a carrot (credit Rasbak)

Tuberculina is proposed to form an amplification stage, where the fungus produces large amounts of genetically identical conidia. The fungus then enters dormancy and the Helicobasidium stage where sexual reproduction takes place, allowing the fungus to remain genetically diverse.

That Tuberculina and Helicobasidium are one and the same is strong evidence for the argument against the use of the fungus as a biocontrol. However, for some Tuberculina species, an equivalent Helicobasidium-stage could not be found. It’s possible that some Tuberculina could have completely abandoned the sexual Helicobasidium stage. If this is the case, Tuberculina may still have potential as a biocontrol agent, although this would require extreme caution.

Fungi are critically under-studied as a kingdom and basic research into their various life-cycles is much needed if we are to effectively control fungal diseases and manipulate fungi for our own benefit. The Jekyll and Hyde characteristics of Tuberculina/Helicobasidium show this clearly and, without fundamental fungal research, we could all too easily still be supporting the traitor in our midst.

See the original paper on Tuberculina and Helicobasidium here.

Biofuels might not be that bad after all

By Joanna Wolstenholme

You have heard of the need to find new sources of energy that do not involve fossil fuels. And you have also probably heard of bioethanol from maize and sugar cane, and the scepticism surrounding their green credentials. This scepticism comes with good reason – these sources of biofuels often divert valuable food from the food chain into fuel production, raising the cost of living. This was vividly illustrated by the food crisis in 2007/8, partly caused by America and the EU incentivising the production of bioethanol. So should we write off biofuels altogether?

Simply put – no – not all biofuels. Second generation biofuels are what you should really be talking about. Write off those inefficient first generation biofuels with their ‘food vs fuel’ baggage, but don’t write off biofuels altogether. Lignocellulosic biofuels are the next big thing – the same green pros, but less of the cons. These biofuels can be made from waste products like straw, maize cobs and bagasse (sugar cane straw), and, excitingly, these technologies are just starting to become commercially viable.

Is straw like this the future of biofuels? (Credit Richard Walker)

Is straw like this the future of biofuels? (Credit Richard Walker)

Lignocellulose is found in the plant cell wall, and is the main component in plant biomass. Unlike sugars (which whilst easily accessible for use in first generation biofuels, are only a small portion of the overall biomass), cellulose is generally an unwanted by-product that goes to waste, thanks to how hard it is to break down. However, researchers are finding new enzymes and treatment methods that are able to attack the cellulose in ever more efficient ways. The first commercial plants have already been built in Brazil and Italy, using biofuel crops like Miscanthus that can be grown on marginal or contaminated land (rather than prime agricultural land), or waste products like straw. These take advantage of government subsidies on renewable electricity to help cover the cost of generating the biofuels whilst scientists work to bring these costs down.

In the 1970s Brazil got worried about its oil supply, so started to move the country to bioethanol. The system was heavily subsidised- but now is self-sufficient, and yields have doubled. Lignocellulosic biofuels could easily go the same way, if only governments are forward-thinking enough to see the potential and invest.

Spinning Straw into Gold

By Sophie Harrington

Everyday millions of people around the country hop into their cars and drive off to work, school, or the shops. This has become such a routine part of our lifestyle that few of us stop to think about what we’re using to power those trips, except when the prices hike or, as we’ve seen recently, drop. Most of us realise that, despite the trumpeted new sources of oil in the Arctic, our petrol habit is highly unsustainable. Wouldn’t it be nice if we could keep our cars and buses running, but on a renewable form of energy?

Some of this has already come to fruition, with cars in the US being driven on up to 15% ethanol derived from corn stalks. This is even more successful in Brazil, where thanks to cars with “flexifuel” engines, drivers are able to fill up with either pure ethanol, or an ethanol/petrol blend depending on the price on a specific day. What a success!

Sugar cane waste, known as bagasse, could one day be used to fuel our cars. (Credit Tele Jane @Flickr)

Sugar cane waste, known as bagasse, could one day be used to fuel our cars. (Credit Tele Jane @Flickr)

Yet this too comes with downside, most notably the appropriation of food (often in the form of maize) for biofuels. While this might not be so obvious to those living in the Western world, sheltered from changing food prices thanks to a wall of subsidies and favourable trade policies, the increasing demand for biofuels has succeeded in driving up the price of such staple grain, seriously hurting net-importing countries. In 2008, riots broke out across the world, from Mexico and Morocco in part due to a sudden, sharp rise in grain prices, partially due to increased demand for biofuel materials in the US and other more developed nations.

Here we are at an impasse—how to both wean ourselves off of unsustainable fossil fuels while ensuring that such biofuel production does not impinge on food production? The answer may lie in technologies still in the development stage, where biofuel is instead derived from agricultural waste and marginal lands. These lignocellulosic biofuels aim to extract sugars from the tough, indigestible material left behind after harvest or extraction of traditional ethanol. By breeding varieties with more easily digestible cell walls, it’s hoped that the extraction of sugar from this material will become not only easier by financially feasible.

Plant cell walls are made up of a host of different components, whose interactions serve to increase the recalcitrance, or toughness, of the wall. This makes it hard for enzymes to digest, which is a benefit when protecting from pests and diseases but hinders exploitation of the sugars. Recent research has focused on modifying the structure and components of the cell wall, thus allowing enzymes better access to break it down. Such research has shown recent success, with variations in hemicellulose structure (a key component linking cellulose fibers in the wall) resulting in increased digestibility and sugar release.

Considering the vast amounts of agricultural waste that are currently either left to rot, or burnt for electricity, a process that could convert this into useful biofuel and other high-value products has the potential to significantly contribute to the fuel consumption. It might seem a bit like Rumplestiltskin asking for straw to be spun into gold, but lignocellulosic biofuels are rapidly becoming more feasible. Here’s hoping that funding bodies and industry giants continue to invest in this exciting alternative to fossil fuels.

Hook, Line, and Sinker: Rise of the Killer Mushrooms

By Nathan Smith

Pleurotus ostreatus, or the oyster mushroom, is a common edible mushroom. As much at home in a stir fry or a soup, one would not expect this culinary baseline to be anywhere other than at the bottom of the food chain. Surprisingly this is not the case, as the oyster mushroom is a stealthy and efficient predator of nematodes.

Pleurotus ostreatus-- a killer in disguise?

Pleurotus ostreatus— a killer in disguise? (Credit Jean-Pol GRANDMONT)

Nematodes, a type of worm, are infamous agricultural pests. The damage caused by these miniature beasts has been estimated at $US80 billion per year, though this is believed to be a severe underestimate as many growers are unaware of them. They even present a threat to the cultivated mushroom industry, being a renowned pest of button mushrooms, so how is it that they fall prey to the oyster mushroom?

The answer is one of ingenuity on the part of the fungus. Unable to chase the nematodes, mushrooms are notoriously sessile, it instead lays a trap. It secretes a toxin which, upon contact with a nematode, proceeds to immobilise the worm in as little as 30 seconds. Fungal hyphae, attracted to the (still alive) nematode through host leakage products released by immobilisation, penetrate one or more of the nematode’s orifices and proceed to digest it.

The unrelated fungus Arthrobotrys also hunts nematodes, but through a completely different mechanism. Instead of stunning its host, it captures it in a hyphal lasso. Known as a constriction ring, this consists of a hypha fused with itself to form a three-celled ring about 20-30 microns in diameter. If, and when, a nematode enters the ring, it triggers the three cells to expand rapidly (within 1/10th of a second) and trap the nematode.

Killer fungi aren’t just of academic interest either. The hunting abilities of fungi, particularly the oyster mushroom, make them potential effective and green bio-control agents. Indeed, initial tests have found the oyster mushroom effective at controlling the Sugar Beet Nematode (Heterodera schachtii), through field tests have yet to be carried out.

It appears that fungi aren’t just passive members of the woodland scenery but rather edible guardians protecting against the nematode threat.

Who said organic farming was less productive?

By Stephan Kamrad

A while ago Joanna reported on a chemical free, organic pest control method that has a lot of advantages to conventionally used pesticides. Studies have shown that organic and comparable agriculture is more sustainable, as measured by indicators like species richness, soil fertility and nitrogen uptake. But even by most experts it is usually dismissed as a fantastical ideal that conflicts fundamentally with our need to feed the growing human population. This month, a new meta-study, published in the Proceedings of the Royal Society B, by scientists from the University of California reveals that the productivity gap between organic and conventional farming might be much smaller than widely believed.

Not so great after all? Credit www.CGPGrey.com

Not so great after all? Credit www.CGPGrey.com

The researchers analysed 115 studies covering over 30 countries and 50 crop species. Organic farming, defined by having no synthetic inputs, was found to be on average 19% (±4%) less productive than conventional farming. But interestingly, this obviously quite a drastic gap shrinks down to 9% (±4%) when the organic farmers use a polycrop system compared to a conventional monoculture. In polycrops, multiple species are grown together, e.g. in alternating rows, resulting in a greater biodiversity than conventional monocultures. This makes them less susceptible to disease and pests and certain combination of crops can act as biological pest repellants and natural fertilisers. In Joanna’s example in Kenya, maize was planted together with Desmodium (which repels the vicious Stemborer moth and also fixes atmospheric nitrogen). Another popular example found in British gardens is intercropping of tomatoes, onions and marigold.

The yield gap was also much smaller (8±5%) when organic farmers used crop rotations, i.e. planted a different crop in each growing season, a system which was once (in the Middle Ages) quite popular in Europe.

But where is the catch? If these techniques are so effective, why are they not used everywhere? More diverse systems are much more difficult to manage. Massive machinery cannot easily be used with companion crops and it is often advantageous for farmers to sell only one or a few crops in bulk. For small farmers in developing countries these techniques are easier to adapt but farmers often are not aware of the possibilities.

All this of course might be slightly too optimistic. After all, non-organic agriculture can also make use of intercropping (rare) or crop rotations (more common). In studies where conventional farming (i.e. the use of pesticides, weed-killers and synthetic fertilisers) was combined with polycropping or crop rotation, the yield gap returned to its original value or was even higher.

Interestingly, the yield gap also depends on what type of crop is under consideration. The yield ratio of organic to conventional farming is lowest for cereal crops, where a lot of effort has gone into the development of high intensity, large scale monocultures but often comes close to 1 for fruits and nuts, were less effort has been made in developing high output systems.

In our world, it is very hard to convince a farmer that he should tolerate a 9% or even 20% yield decrease for the prospect of a healthier agro-ecosystem, that is diverse, unpolluted and resilient to stress and disease. Diversification (be it over time as in crop rotations or over space as in polycrops) can raise organic farming yields and make it more competitive to conventional farming. With more investment it may be possible for the yield gap to be reduced even further.

Reference:

Ponisio LC, M’Gonigle LK, Mace KC, Palomino J, de Valpine P, Kremen C. (2015) Diversification practices reduce organic to conventional yield gap. Proc. R. Soc. B, 282:20141396. DIO: dx.doi.org/10.1098/rspb.2014.1396

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.

coral

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