Biology News & Research

16 March 2012

Drought costs millions of lives across the world, as crops fail and people and animals starve. A team of American scientists researching the problem have found that plants 'learn' how to deal with drought, and can survive it better a second time around. 

Researchers at the University of Nebraska knew that home gardeners often withheld water for a few days before transplanting a plant, to 'harden them up' before the move. However, there seemed to be nothing about this in the scientific literature, and the team was intrigued.

Working with Arabidopsis, a member of the mustard family considered an excellent model for plant research, the team compared the reaction of plants that had been previously stressed by withholding water to those not previously stressed. The pre-stressed plants bounced back more quickly the next time they were dehydrated. Specifically, the nontrained plants wilted faster than trained plants and their leaves lost water at a faster rate than trained plants.

"The plants 'remember' dehydration stress. It will condition them to survive future drought stress and transplanting," Michael Fromm, one of the team, explained.

The team found that the trained plants responded to subsequent dehydration by increasing transcription of a certain subset of genes. During recovery periods when water is available, transcription of these genes returns to normal levels, but following subsequent drought periods the plants remember their transcriptional response to stress and induce these genes to higher levels in this subsequent drought stress.

Arabidopsis forgets this previous stress after five days of watering, though other plants may differ in that memory time.

This is the first instance of transcriptional memory found in any life form above yeasts.

This discovery may lead to breeding or engineering of crops that would better withstand drought, although practical applications of these findings in agriculture are years away, Fromm said.  Perhaps scientists can modify those instincts in plants to help maintain or improve productivity during times of drought, he added.

However, the team has some immediate advice for home gardeners.

"If I was transplanting something, I would deprive it of water for a couple of days, then water overnight, then transplant," Fromm said.

Read the research paper online in Nature Communications

Read the full announcement on the University of Nebraska Lincoln website

What's are the world's record breaking organisms?

There's a new contender for oldest living organism - and it isn't a tortoise, a mollusc or a coral. Instead, it's a vast patch of seagrass swaying underneath the Mediterranean.

A researcher, Carlos Duarte of the University of Western Australia in Perth sequenced the DNA of Posidonia oceanica (an underwater plant known as seagrass because its thin leaves resemble grass) at 40 sites across 3500 kilometres of seafloor, from Spain to Cyprus. One patch off the island of Formentera, near Ibiza, was genetically identical over 15 kilometres of coastline. The plant reproduces by cloning, so these meadows can be considered to be one organism. The team says that "the largest natural clones can extend over hundreds or thousands of metres and potentially live for centuries."

The team worked out how old the clonal patches of seagrass could be, based on annual growth rates. Their calculations suggest that the meadow must be between 80,000 and 200,000 years old, making it the oldest living organism on Earth.

19th January 2012

Hundreds of beautiful sections of fossil wood, many of them collected by Darwin on his voyage on his Beagle, have been found in a dusty cabinet in the corner of a warehouse.The collection is a microcosm of the history of science in the 19th century, and tells stories of friendship, romance - and rivalry.

Dr Howard Falcon-Lang was exploring the huge warehouse of the British Geological Survey, when he turned down a narrow corridor and came across a 19th century cabinet amid the packing crates, the key still in the lock. He opened the cabinet, pulled out a specimen and held it up towards the fluorescent lights. To his astonishment, the specimen was neatly labelled 'C. Darwin, Esq'. 

The material was collected together by the great 19th century botanist, and Darwin's best friend, Joseph Hooker, who travelled the globe in search of botanical rarities. Among the slides is material from his voyage around round the world, including trips to Australia in search of fossil plants. The collection also includes some of the first thin sections ever made by William Nicol, the pioneer of petrography, in the late 1820s.

During the course of Darwin's famous voyage on the Beagle (1831 - 1836), he visited Chiloe Island off the coast of Chile. Here, Darwin encountered ‘many fragments of black lignite and silicified and pyritous wood, often embedded close together’. Some of these fragments found their way into Hooker's collections, as part of their exchanges of discoveries.

But who would think of fossil sections as being a romantic gift? Many of the specimens are labelled 'Miss Henslowe' - perhaps Miss Frances Henslow, who became engaged to Joseph Hooker in 1847, a few months after he assembled this collection. Frances Henslow was the eldest daughter of John Henslow, Darwin's mentor, and the man who found him his place on board the Beagle. John Henslow has a special connection with Science and Plants for Schools - he created Cambridge Botanic Garden, where we are based, as an exploration of his ideas about variation in nature and 'monster' plants.

Other fossil sections tell a story of rivalry between two 19th century scientists. Willian Nicol, who invented the polarizing microscope, and pioneered the science of petrography, the detailed study of rocks. His friend and supporter was the wealthy Henry Witham, who sourced fossil plants for Nicol from his many contacts. But the collaboration turned sour when Witham published a book based on both their work - without putting Nicol's name on the cover. Nicol was furious, and the result was a falling out between the friends that lasted until their deaths. 

The first parts of this incredible fossil collection is now available to see online - count the rings of the fossil trees to see how old they were when they died.

See the fossil collection online, and read a collection of articles about its background.

You can read Darwin, Hooker and Henslow's letters online at the Darwin Correspondence Project.

Why would any plant want to bury its leaves underground? We all know that leaves are used for photosynthesis, so surely the idea makes no sense.

That's why Professor of Botany Rafael Oliviera was so intrigued when a colleague returned from a field trip and described a plant with adapatations of a very peculiar kind.

"I had never seen a plant with underground leaves before," he said. "It doesn't make a lot of sense to have leaves underground because there is less sunlight -- so we hypothesized they're getting some other kind of benefit from the leaves."

Philcoxia minensis lives in sandy soils of the Cerrado, a tropical savannah region in Brazil and one of the world's 34 'biodiversity hotspots'. Philcoxia has both 'normal' leaves on stems above ground, and a network of minature leaves, each no larger than a pinhead, underground.

It's not that the underground leaves get no sunlight at all. In fact, they can capture sunlight through the white, sandy soil. However, that's not their only function.

These underground leaves secrete a sticky substance that traps nematodes, miniscule worms in the sandy soil. To test if the plant was truly digesting the worms, the scientists fed the plants nematodes marked with an uncommon isotope of nitrogen. When they tested the plant's leaves, they found the same isotope present, confirming that the plant was indeed using enzymes to digest the worms.

This is the first time that a plant has been found which uses underground leaves to trap prey, and the first plant that has been found to digest nematodes, a common strategy in fungi. 

"It's a great example of how plants, which can't move to find food and water, are able to develop interesting mechanisms to deal [with] extreme environments," says Rafael Oliviera

It's also a reminder of how important the Brazilian Cerrado is for conservation - but it's being destroyed at faster than the Amazon rainforests, largely to grow soy and for cattle ranching.

Find out more about the Brazilian Cerrado in this video by the Royal Botanic Garden Edinburgh and the WWF.

Find out more about Philcoxia minensis at Inside Science.

17th January

We often hear about the food-fuel conflict when discussing biofuels - but a breakthrough by British plant scientists has brought us one step closer to breeding multi-use crops, which produce both food and fuel.

The majority of the energy stored in plants is contained within the woody parts, and billions of tons of this material are produced by global agriculture each year in growing cereals and other grass crops, but this energy is tightly locked away and hard to get at. This research could offer the possibility of crops where the grain could be used for food and feed and the straw, much of which is currently thrown away, used to produce energy efficiently.

Professor Paul Dupree, of the University of Cambridge’s Department of Biochemistry, explains, “Unlike starchy grains, the energy stored in the woody parts of plants is locked away and difficult to get at. Just as cows have to chew the cud and need a stomach with four compartments to extract enough energy from grass, we need to use energy-intensive mechanical and chemical processing to produce biofuels from straw.

“What we hope to do with this research is to produce varieties of plants where the woody parts yield their energy much more readily – but without compromising the structure of the plant. We think that one way to do this might be to modify the genes that are involved in the formation of a molecule called xylan – a crucial structural component of plants.”

Xylan is an important, highly-abundant component of the plant cell wall, holding the other molecules in place to make a plant robust and rigid. This rigidity locks in the energy that we need to get at in order to produce bioenergy efficiently.

Grasses contain a substantially different form of xylan to other plants. The team wanted to find out what was responsible for this difference and so looked for genes that were turned on much more regularly in grasses than in the model plant Arabidopsis. Once they had identified the gene family in wheat and rice, called GT61, they were able transfer it into Arabidopsis, which in turn developed the grass form of xylan.

Dr Rowan Mitchell of Rothamsted Research continues, “As well as adding the GT61 genes to Arabidopsis, we also turned off the genes in wheat grain. Both the Arabidopsis plants and the wheat grain appeared normal, despite the changes to xylan. This suggests that we can make modifications to xylan without compromising its ability to hold cell walls together. This is important as it would mean that there is scope to produce plant varieties that strike the right balance of being sturdy enough to grow and thrive, whilst also having other useful properties such as for biofuel production.”

The tough, fibrous parts of plants are also an important component of our diet as fibre. Fibre has a well established role in a healthy diet, for example, by lowering blood cholesterol. The team have already demonstrated that changing GT61 genes in wheat grain affects the dietary fibre properties so this research also offers the possibility of breeding varieties of cereals for producing foods with enhanced health benefits.

Teachers who attended the Biology in the Real World lecture on the future of biofuels at the ASE Annual Conference 2011 will remember Dr Jen Bromley, one of the team that made this breakthrough, talking about their research. Her presentation can be downloaded from the Society of Biology website.

A group of teachers and scientists, including Jen Bromley, have produced a set of free practical protocols and teaching resources for looking at next-generation biofuels in the classroom.

Read more about the discovery on the University of Cambridge website.

Find out more about the teams of researchers working on next generation biofuels at the BBSRC Sustainable Bioenergy Centre.

3rd Jan 2012

From the UK Plant Sciences Federation

Dormant seeds in the soil detect and respond to seasonal changes in soil temperature by changing their sensitivity to plant hormones, new research by the University of Warwick has found.

This sensitivity alters the depth of dormancy, indicating to the seed when it is the right time of year to germinate and grow.

The seeds of common weeds can survive in the soil in a dormant state for years, in some cases decades, spelling issues for food security when they emerge to compete with crops.

New DEFRA-funded research by the University of Warwick sheds light on how hormones regulate the dormancy cycle of seeds in the soil using seeds of Arabidopsis - commonly known as Thale Cress - a close relative of many common weeds and crop species.

The new insights, which come from combining modern molecular biology with traditional seed ecology, could be of long-term help in reducing the use of herbicide on farms.

It is also of interest to those working to ensure biodiversity by understanding how dormancy and germination in wild plants is regulated.

Despite the importance of dormancy cycling in nature, very little is known about its regulation at the molecular level.

Professor Bill Finch-Savage and Dr Steve Footitt in the University of Warwick’s School of Life Sciences looked at gene expression over the dormancy cycle of Arabidopsis seeds in field soils to see how it is affected by the seasons.

They found that gene sets related to dormancy and germination are highly sensitive to seasonal changes in soil temperature.

A balance between the hormones abscisic acid (ABA) and gibberellic acid (GA) is thought to be central to controlling dormancy and germination,

One set of genes is regulated by ABA, which is linked to dormancy, whereas GA controls genes which act to increase the potential for germination.

Using an Arabidopsis strain whose seedlings emerge in late summer and early autumn, they found that as the soil warms up, seeds become less sensitive to ABA and more sensitive to GA, which brings them out of dormancy and spurs them towards germination.

Once dormancy starts to recede, increased sensitivity to light, nitrate and the differences between day and night temperatures play a bigger role in signalling that it is the right time to germinate.

Dr Footitt said: “Many will have seen how the amount of weeds in their garden differs with the weather from year to year.

“Understanding how this happens will help us to predict the impact that future climate change will have on our native flora and the weeds that compete with the crops we rely on for food.”

“Our research sheds new light on how genetics and the environment interact in the dormancy cycling process.

“By looking at seeds over an annual cycle we now have a clearer idea of how seeds sense and react to changes in the environment throughout the seasons so they know the best time to emerge into plants.”

The research is published in the Proceedings of the National Academy of Sciences.

Professor Finch-Savage and Dr Footitt have been awarded a BBSRC grant to investigate further how climate has an impact on dormancy cycling and how genetics and the environment interact in the dormancy cycling process

http://www2.warwick.ac.uk/newsandevents/pressreleases/spring146s_rising_soil/

In recent months, rising food prices across the world have resulted in riots in some parts of the globe, and in a quiet unease in others. We have a growing world population, but there is a risk that factors such as pollution, changing sea levels  and other issues may in fact reduce our food supply.

A recent article by UK plant scientists in the Journal of Experimental Botany looked at the role of ozone pollution, and highlighted the ways in which it can reduce our food supply. They describe how ozone is damaging our staple food crops - including wheat, rice and potatoes - when they are growing in farmers' fields. They also report that this problem may well become worse in the future, especially in, for example, SE Asia, where much of our global food supply is sourced.

Ozone is a polluting gas in the air around us formed from emissions from motor vehicles and from industry. At ground level, ozone is damaging, even though we need it in the upper atmosphere to protect us from UV radiation. Its concentration here at ground level has been increasing since the middle of the last century, so that it is now present at levels high enough to injure plants.

Ozone can stop plants from fixing sunlight into energy via photosynthesis, can cause their leaves to die and fall off early, and can stunt their growth. All this means that the damaged plants have fewer resources (carbon and nutrients) to put towards forming their edible parts, such as wheat and rice grains, maize kernels, potato tubers, pea and bean pods and so on. Sometimes the effects are not even visible to the naked eye because they accrue over the course of the whole growing season so a farmer may not even realise why his or her yield is smaller. Also, it is difficult to tell without sophisticated monitoring equipment when the air around us has become polluted enough with ozone to affect plants.

Because ozone pollution is predicted to become worse in some areas such as Asia in the next two or three decades, the source of much of our food supply, it may soon have an even bigger impact on crops in farmers fields. Furthermore, ozone's capacity to reduce yields may be compounded by other types of climate change. For example ozone reduces the ability of some plant varieties to withstand other stresses such as drought, and we predict, says Dr. Sally Wilkinson of the Lancaster Environment Centre at Lancaster University, that the same may be true of some crop varieties. However other varieties are actually protected from some of the effects of ozone pollution by drought, because pores in the leaf surface through which ozone can enter the plant are often closed in droughted conditions. More research is needed to choose carefully which crop varieties can withstand ozone pollution, especially when it is combined with other types of environmental stress. This is particularly important for food security, given the increasing world population, which needs more, rather than less food to be grown by our farmers, despite the increasingly erratic climate that we and our food plants are being subjected to.

The research was done by plant scientists at the Lancaster Environment Centre (LEC), Lancaster University, and from the Centre for Ecology and Hydrology, Bangor.

Further information on the economic impacts of ozone damage to crops in Europe, on which crops are the most sensitive to ozone, along with a review of the implications for food supplies from SE Asia, can be found in two new reports written by Dr Gina Mills and colleagues at CEH Bangor with inputs from the Lancaster University scientists (downloadable from http://icpvegetation.ceh.ac.uk/).

An abstract of the article can be read on the JEB website.

Thanks to the UK Plant Science Federation for this article.

In this video, ecologist Dr Markus Eichhorn talks about the different christmas tree species, how they cope with the central heating in your home and why he prefers natural christmas trees to artificial ones.

http://www.plantcellbiology.com/2011/12/the-science-of-christmas-trees/

Malaria is one of the world’s most serious public health problems, claiming almost a million lives every year and undermining development in some of the world’s poorest countries. A UK science lab has been fighting against malaria for years - through plant breeding.

At present, the most effective cure for malaria is Artemisinin Combination Therapies (ACTs), whose active ingredient is artemisinin, extracted from the plant Artemisia annua. However, quality Artemisia seeds are scarce and the world’s total production of artemisinin is struggling to meet rising global demand for ACTs.

Through a marker-assisted breeding programme, and after a series of field trials in different parts of the world, the Centre for Novel Agricutural Products (CNAP) at the University of York has developed new varieties of Artemesia annua seeds, which not only yield high quality artemesinin, but are robust, resistant to pests and diseases, and perform well under a range of regional agricultural practices.  However, Professor Diana Bowles has all along argued that a scientist's job is not merely to develop the new plant variety, but to get it out into the hands of those who need it.

CNAP has now partnered with a commercial seed organisation, East-West Seed, to produce their new varieties in commerical quantities. This new supply of improved seed will help build up a robust supply chain for the production of Artemisinin Combination Therapies (ACTs), the World Health Organisation recommended treatment for malaria.

Through the partnership, large-scale commercialization and distribution of the seeds to Artemisia growers are expected in 2012, targeting 20% of the global Artemisia cultivation acreage.  Annual global demand for ACTs is expected to increase beyond the current level of 250 million treatments to up to 310 million by 2015 and the new high yielding seeds will help achieve the strategic aims of universal coverage of ACTs and access to treatments.

This provides an excellent opportunity for the new Artemisia varieties developed at York to make a real difference to the fight against malaria