Biology News & Research
News - Why climate change brings spring forward
22nd Mar 2012
With buds bursting early, only for a mild winter to turn Arctic and wipe them out, we are witnessing how warm weather can trigger flowering, even out of season, and how important it is for plants to blossom at the right time of year.
BBSRC-funded scientists have unpicked why temperature has such a powerful affect on how plants flower. In research to be published in the journal Nature, scientists from the John Innes Centre on the Norwich Research Park have identified the switch that accelerates flowering time in response to temperature.
With warm air, a control gene, called PIF4, activates the flowering pathway, but at lower temperatures the gene is unable to act.
"What is striking is that temperature alone is able to exert such specific and precise control on the activity of PIF4," said Dr Phil Wigge, the lead scientist in the study.
Previously, it has been shown that PIF4 is vital for controlling other aspects of plant responses to warmth, for example growth, but this is the first time that the gene has been shown to be necessary for the activation of flowering by temperature.
Flowering is activated by a special molecule, called Florigen. Florigen is activated by many signals, including the longer days of spring. Some plants rely more on temperature, others more on daylength to control key stages in their life cycle such as leaf emergence and flowering. This is reflected in the old saying "Ash before Oak, you're in for a soak; Oak before Ash, you're in for a splash."
While the pathway that activates florigen in response to daylength has been known for many years, how temperature activates Florigen has been a mystery until now.
At lower temperatures, plants do still flower eventually but via other pathways. Any acceleration triggered by PIF4 is lost as it does not bind to and switch on the Florigen gene. As temperatures increase, PIF4 is able to bind the Florigen gene and trigger flowering.
"Our findings explain at the molecular level what we observe in our gardens as the warmer temperatures of spring arrive," said Wigge. "It also explains why plants are flowering earlier as a result of climate change."
Wigge and colleagues hope their research will eventually allow temperature-resilient crops to be developed. Crops plants often respond very strongly to warmer temperatures, reducing yields. By understanding at the molecular levels how plants sense temperature, the team hopes to breed crops which are more resilient to climate change.
"Knowing the key players in the temperature response pathways will be a valuable tool for safeguarding food security in an era of climate change," said Wigge.
With all seven of the warmest years on record in the UK having occurred in the past decade, the race is on to help crops cope with the effects of higher temperatures caused by climate change.
The John Innes Centre is strategically funded by BBSRC.
From the Plant Science Federation website
Reference: Transcription factor PIF4 controls the thermosensory activation of flowering, Nature doi:10.1038/nature10928
News - Plants 'remember' drought and prepare
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
News - Oldest, biggest, highest, weirdest
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.
News - Darwin's lost plant fossils found again
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.
News - Unique plant with underground leaves
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.
News - Breakthrough for Biofuels
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
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
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.
News - Spring temperatures see hormones wake seeds
3rd Jan 2012
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
News - How ozone pollution reduces food supply
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.
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.
Advent Calendar - The Science of Christmas Trees
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.
News - Getting malaria cures out of the lab
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
News - How parasites modify plants to attract insects
9th Nov 2011
alter their hosts - for example malaria parasites can make humans more
attractive to mosquitoes - but how they do it has remained a mystery.
Now, scientists have identified for the first time a specific molecule from a parasite
that manipulates development to the advantage of the insect host. The work was done by UK plant scientists at Norwich, at the John Innes Centre.
This finding could help scientists to find new ways of managing the spread of insect-borne crop diseases. This will be vital in order to ensure future food security, especially, in this case, in the face of climate change.
"Our findings show how this pathogen molecule can reach beyond its host to alter a third organism," said Dr Saskia Hogenhout from JIC.
Leaf hoppers are tiny sap-sucking, highly mobile and opportunistic agricultural pests. Certain species can acquire and transmit plant pathogens including viruses and phytoplasmas, which are small bacteria. Dr Hogenhout and her team focused on a phytoplasma strain called Aster Yellows Witches' Broom, which causes deformity in a diverse range of plants.
"It is timely to better understand phytoplasmas as they are sensitive to cold and could spread to new areas as temperatures rise through climate change," said Dr Hogenhout.
Infected plants grow clusters of multiple stems which can look like a witches' broom or in trees like a bird's nest. The strain was originally isolated from infected lettuce fields in North America.
The phytoplasma depends on both the leafhopper and the plant host for survival, replication and dispersal. The new findings show how it manipulates the interaction of the plant host and insect vector to its advantage.
The scientists sequenced and examined the genome of the witches broom phytoplasma and identified 56 candidate molecules, called effector proteins, which could be key to this complex biological interaction.
They found that a protein effector SAP11 reduces the production of a defence hormone in the plant that is used against the leafhopper. As a consequence, leafhoppers reared on plants infected with witches broom laid more eggs and produced more offspring. The leafhoppers may also be attracted to lay eggs in the bunched branches and stems.
The higher fecundity rate is probably matched by a similar increased rate in transmission of the witches broom phytoplasma by leafhoppers to other plants.
"Phytoplasmas that can enhance egg-laying and offspring numbers in leafhoppers are likely to have a competitive advantage," said Dr Hogenhout.
Given their opportunistic nature, the leafhoppers are likely to migrate to uninfected plants and spread the pathogen.
"This is a vivid example of the extended phenotype, a concept put forward by Richard Dawkins, where an organism's phenotype is based not only on the biological processes within it but also on its impact on its environment," said Dr Hogenhout.
Find out more about phytoplasmas in this Catalyst article, written for students studying GCSE and A-level Biology.