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.

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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.

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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.

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

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…

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.

800px-Fortunella

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.

 

 

Eyes in the Sky: Agriculture and the Rise of Satellite Technology

By Sophie Harrington

When you think of farming, satellites probably aren’t the first thing that comes to mind. Yet in the coming years, farming may be more and more tied to the information gathered by satellites orbiting the globe. New technologies are being developed to integrate precision satellite data with farming practices around the world. These techniques hold the potential for not only increasing the efficiency and yields of farms, but also to reduce the environmental impact of intensive farming.

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The future of agriculture? (credit NASA Goddard Space Flight Center)

In the United Kingdom, a group of companies known as the Courtyard Partnership are hoping to revolutionize farming by providing in depth data from satellite imaging and soil analysis. By providing farmers with information on soil variation across their fields the group hopes to facilitate increases in yield while at the same time allowing the use of more environmentally friendly farming practices.

Soil brightness scanning by satellites provides information on soil texture, moisture, and organic composition which enable farmers to make distinctions between different soil types. This in turn allows soil inputs to be calibrated based on the specific soil “zone” determined through the combination of satellite imaging and soil sampling on the ground. Initially this could allow farmers to reduce wasted fertiliser by applying the optimum amount for each soil zone..

Later on, satellite images can also be used to provide data on chlorophyll cover, the pigment in plants which gives them their green colour. This acts as a proxy for plant nitrogen levels, which influence chlorophyll content. If the chlorophyll is lower than ideal, this can be compensated for by increasing fertilizer input. At the same time, the satellite images also provide data on the “Normalised Difference Vegetation Index” (NVDI). This provides a measure of crop growth (or “thickness” on the ground).

Fertiliser spreading on field

The Courtyard Partnership hopes to reduce the use of fertilizers through a better understanding of soil properties. (credit kitching71)

With this data, farmers are more able to monitor the total health and growth of their crops on a large scale. Indeed, the digital files containing the satellite data, and thus the corresponding chlorophyll and NVDI levels, can be tied to the farm machinery, allowing automatic changes in inputs ranging from seeds to fertiliser. This type of high precision data has the potential to dramatically decrease pollution and fertiliser waste. According to the Courtyard Partnership, use of such techniques could lead to savings of 45 tonnes of carbon dioxide emissions, as well as significant decreases in fertilizer use.

Considering the serious environmental consequences that have stemmed in part from the industrialization of farming, such techniques seem promising. The extensive application of fertilizers since the Green Revolution of the 50s and 60s have indeed led to increases in agricultural production, but at serious costs. Fertilizer runoff into rivers and streams has been implicated in significant algal blooms. The dead zone of the Gulf of Mexico arises from the nitrogen and potassium fertilizer runoff polluting the Mississippi river. The resulting algal blooms cause hypoxia, or low oxygen levels, killing off much of the marine life in the area.

The concept of using satellites in agriculture may seem alien for now, but if we want to solve our problems on the ground we may be best off looking to the sky.

Agri-Cultural Psychology: Does rice explain the difference between East and West?

By Nathan Smith

Humans cultivate plants. From the first steps of domesticating wheat, through the Green Revolution, to Genetic Modification, people have selected for plants to suit their needs. Indeed, even wild plants have inadvertently been selected for by man and many of the characteristics we associate with weeds have only arisen through humanity’s persistent attempts to remove them. In reverse, humanity can be seen as master of their domain and largely immune to environmental pressures. Rather than being shaped by it rather we shape it to meet our needs.

Does rice bring out community spirit? (Credit the International Rice Research Institute)

Does rice bring out community spirit? (Credit the International Rice Research Institute)

But this was not always the case. A recent paper in Science argues that our cultural psychology, far from being an artificial construct, is instead firmly rooted in our agricultural past.  Specifically, the paper aims to explain the differences between Eastern and Western cultures. Over the past couple of decades, the difference between these broad groups has been explored and characteristics described (the West is more individualistic and analytic whereas the East more communistic and holistic). Whilst several explanations have been proposed, they all display flaws and are deemed unsatisfactory or only partially responsible. The theory proposed in the paper is that the differing general characteristics can be explained through the historic communities’ preference for growing wheat or rice.

The reasoning behind this is that rice, in comparison to wheat, is a more labour intensive crop, requiring approximately twice as many working hours for the same yield. Indeed it was noted that a husband and wife team would be unable to farm a plot large enough to meet the needs of their family, thus implying the necessity of interdependence.  Rice also requires irrigation, which needs coordinated water use and shared labour to produce the irrigation network.

Wheat-- supporting individualism? (Credit Rob Young)

Wheat– supporting individualism? (Credit Rob Young)

To assess this cultural theory, researches conducted a study comparing the psychological traits of individuals from wheat and rice growing regions. The study took place in China, which can traditionally be divided between the wheat growing north and rice growing south, and focused only on the Han Chinese, thus removing any confounding variables of nationality or ethnicity. Account was also taken for the wealth and rate of infectious diseases in the county, both of which have been proposed as explanations for the differences seen in cultural psychology. Both were inaccurate predictors of individualistic or communistic cultural psychology. However, the region’s dominant crop was found to be an accurate predictor, thus supporting the hypothesis suggested by the theory. Research into other countries with a rice-wheat split, such as India and Indonesia, are expected to show similar differences in cultural psychology.

How this psychology is passed down generations and if the method of rice growing has an effect on the psychology developed are questions still to be answered but it appears that whilst humanity has shaped plants, plants have also shaped humanity.

To read more, take a look at the paper here.