"Synthetic Biology" is a term bandied about with increasing frequency but what does this actually mean? How is it different to standard procedures that experimentally alter organisms?
The key difference is that synthetic biology seeks to re-design or introduce complete biological processes. This is done by introducing artificial systems through a "bottom up" approach using DNA "modules" or "parts", a bit like the building blocks found in Lego kits. This is only possible where there is a sound knowledge of the processes concerned, and where they can be introduced without interrupting the normal functioning of the organism.
Plants are attractive candidates for synthetic biology as their cells are split into defined compartments (chloroplasts, mitochondria, etc.), and have well-understood pathways that determine the flow of metabolites. Hence, new functions can be packaged into organelles, where they cannot disturb other vital processes. This concept is highly exciting and has prompted a wealth of inspired "blue sky thinking" projects. Just imagine - what functions would you introduce into a plant? "Naturally fluorescent" Christmas Trees? (Just think - no more tangled wires or broken bulbs on the fairy lights!). "Odour-removing" houseplants that exude pleasing fragrances? Foodstuffs that combined novel or unusual flavours? Perhaps these are more "cosmetic" than useful, but one idea with great potential is the use of plants as biosensors.
Carbon monoxide poisoning is a constant threat from appliances that burn fuel, particularly as this lethal gas cannot be seen or smelt. The gas is produced when there in insufficient oxygen for the combustion process to be complete. Besides causing death, symptoms of carbon monoxide poisoning include headaches, breathlessness, nausea and dizziness. Hence, gas boards and product manufacturers advise clients to be vigilant in checking their homes and appliances regularly. But what if there was a "natural sensor" - a plant capable of giving out a clear signal when CO levels crept dangerously high?
An attractive idea and not as outlandish as it sounds! Professor June Medford from Colorado State University and her group have introduced a similar idea into the model plant, Arabidopsis thaliana (thale cress). Their aim was to design a sensory system for
Synthetic reporter systems are already well developed in plants and include introducing the gene for Green Fluorescent Protein (GFP) from Jellyfish, producing a green glow under standard conditions. The problem with these systems is that they are difficult to reset, and often require specialist equipment to detect, making them unsuitable for constant monitoring. Medford's group decided to use chlorophyll loss, a natural process which we are familiar with during Autumn, when the leaves die (senesce). Normally this occurs very slowly, over the course of several days; for chlorophyll loss to act as a useful biosensor, however, this would have to happen much faster. Outside of Autumn, the chlorophyll pigment is constantly turned over, with levels maintained by balancing synthesis and degradation. To induce rapid chlorophyll loss, the team introduced two synthetic gene circuits that would respond to an input signal by both inhibiting chlorophyll synthesis and promoting breakdown. In this case, the input signal was the synthetic steroid hormone 4-hydroxytamoxifen (4-OHT). To prevent chlorophyll from being manufactured, this gene circuit contained double stranded interfering RNA (diRNA) constructs specific for two key enzymes for chlorophyll manufacture, protochlorophyllide oxidoreductase (POR) and GENOMES UNCOUPLED 4 (GUN4). Interfering RNA constructs work by binding to the mRNA products of target genes (the coding molecules which allow DNA sequences to be translated into proteins) and causing them to be degraded by the RNA Induced Silencing Complex (RISC). This effectively silences the genes, whilst leaving the nuclear DNA intact. The group also introduced a gene circuit which activated the enzymes which break down chlorophyll. Interestingly, when the circuits were introduced to Arabidopsis separately, there was no detectable change in "greenness", suggesting that the plants could compensate by inhibiting degradation or upregulating synthesis. However when both synthetic circuits were introduced, the plants rapidly lost chlorophyll, becoming white within 48 hours. This is a distinct phenotype from the yellow colour which is revealed when the leaves senesce in Autumn - very useful to avoid confusion between a natural process and an alarm system! In addition, when 4-OHT was removed, the plants regained their green colour, effectively "resetting" the system. This is crucial to allow multiple detection and for the plants to act as "long-term sentinels".
Intriguing science! And what would you do with it? Please leave your comments below!
Reference: "A synthetic de-greening gene circuit provides a reporting system that is remotely detectable and has a re-set capacity", Antunes et al. 2006. Plant Biotechnology Journal, Volume 4, Issue 6.
Pages
▼
Tuesday, 29 April 2014
Tuesday, 15 April 2014
Gatsby Training Weekend, Cambridge: Day 3
I was sad to find that the final day of the training weekend had come around so soon, but there was still a morning of sessions before the final departure. I joined the other first year PhD students for a session focusing on ' How to get the most out of conferences and placements'. I hadn't appreciated just HOW frequently scientific conferences are used as events for scouting out job opportunities and, in the case of lab group leaders, recruiting new talent. Increasingly, it seems that networking is an import at factor in charting the careers of early stage researchers, it's what you know, or how well you do it, but who you know - and who they know too! It was reassuring to hear that most scientists welcome interest in their work and even speculative enquiries about available lab positions... In the past I always felt too awed to approach senior scientists.
Wisteria on the building at Jesus College
We then reconvened to discuss the usefulness of the sessions and give suggestions for the next year. It was generally agreed that the event had been extremely useful, besides an enjoyable social occasion. Following Dr Barsby's talk yesterday, it was proposed that we visit The NIAB Innovation Farm as an excursion... I hope that goes ahead as I saw this project in its early stages whilst undertaking my placement at NIAB last year ( researching semi- dwarfing genes in wheat) so it will be interesting to see how it has developed.
A final lunch, a last look around the gardens laid out in the glorious sunshine then home... But not quite yet! Before catching my train, I had arranged to meet two friends who had also been on the Amgen Scholars Scheme during the same year that I was. This programme sponsors roughly twenty students each year to do an eight week research placement in Cambridge each year. We stayed together in St Edmunds college but worked on completely different things ( everything from NMR to diabetes to brain scanning) across a wide range of departments. It was lovely to catch up and we had a look at the temporary exhibition in the Fitzwilliam Museum: From Root to Tip: Botanical Art in Britain. My friends were very patient with me as I spent quite a while peering at the delicately worked petals and lustrous colours, as though by looking closely at them I would obtain the skill myself by osmosis. Although not a large collection of drawings, they were carefully chosen to show a range of compositions, from scenes of wildflowers to bunches of mixed ornamentals and single species. It has renewed my enthusiasm for botanical art and I have resolved to try and improve my skills although enrolling on a course at The Royal a botanical Gardens at Kew might be taking it too far...
Antirrhinum (Snapdragon) in the Fitzwilliam Museum Exhibition "From Root to Tip: Botanical Art in Britain"
A wonderful weekend with a lovely, supportive group of people. I remain indebted to the Gatsby Plants Foundation for their encouragement and for giving me the chance to present my work to fellow plant scientists... Besides giving me the brief experience of the student life in Cambridge! I'm already looking forward to the next.
Gatsby Training Weekend, Cambridge: Day 2
I had forgotten how beautifully quiet Cambridge Colleges were.... although perhaps staying outside the main term time makes a difference! Nevertheless, it made a nice change to the traffic of Fulwood Road.
View from my College window... no piano in the room this time!
It was just as well to have had some rest as the program promised a demanding schedule. First of all, we were privileged to hear insights of wisdom regarding delivering scientific presentations. After learning about the limited capacity of audiences to take in so much data at once (especially after sitting through a whole seminar of talks), I cringed as I looked at my "over-busy" slides. I realized that I had even included information that I didn't expect the audience to read - so why was it even on there?! My eyes were opened to the effectiveness of "building" slides - adding images and data one at a time rather than throwing it up all at once. "Unfortunately" the camera developed a technical error so I wasn't able to watch a video of myself presenting my talk from yesterday ...
After consoling myself over tea/coffee, we were introduced to the panel for the careers session. The Gatsby Supervisors were particularly keen to stress that a career in science is not limited to the bench so had invited Etta Collier, a patent attorney, and Tom Mentlak, who worked in management consultancy. It struck me that these roles, whilst not involved with direct research, allowed one to keep in touch with the latest scientific innovations and ideas. The two speakers did illustrate a real contrast in work/life balance however. Whilst Etta felt fortunate to have a flexible job which allowed her to dedicate time to her family, Tom frequently found himself working challenging hours (including ringing Californian clients at 3 'o clock in the morning) with the promise of an impressive salary (so impressive, he wouldn't even tell us what it was!). As for me, I'm still not sure what direction my career will take but will certainly not rule out a role in the patenting industry. After such a rigorous morning, we were grateful for the chance to unwind a bit over lunch in the upper hall.
For the second half of our session on giving a professional scientific presentation, our group took an excursion to the lecture theatre of the Zoology Department. It felt a little daunting to be hooked up to a proper microphone and to stand behind the bizarre array of technology arranged on the lecturers desk. To my surprise, however, I found that I preferred speaking in a large auditorium, compared with a small, cramped, echoing seminar room and even enjoyed it once I got into my stride... But I still need to work on my projection! I wonder, will I ever stand in that position again as a lecturer of plant physiology to hundreds of students?
And today's lecture.... will I be comparing this to a similar photograph in the future?
To make the most of the afternoon sunshine, the whole group were treated to a tour of the college and grounds by Dr David Hanke, plant biochemist and a Fellow of Jesus College. Our eyes were opened to how the innocuous looking buildings before us were really a hodgepodge of architecture that had been recycled, hidden, altered and rediscovered over the centuries. Apparently, out of all the Cambridge colleges, Jesus College has been continuously lived in for the longest although it was originally founded as a nunnery. After touring the chapel and cloisters ( and learning a little about the resident ghosts)' we took a circuit through the woods around the perimeter, stopping to hear extraordinary tales about some of the trees and the plant hunters who had bought them to Cambridge. Strangely enough, the walk finished by the local pub ' The Maypole' where it was decided to have a refreshment break in the beer garden!
Admiring the beautiful trees (and learning some of the tall tales behind them) in the grounds of Jesus College
We didn't have long to sunbathe however, and it was soon time to return to college to meet Dr Tina Barsby, our before- dinner speaker. This provided a fascinating insight into the operation of a large- scale agricultural research group, as Dr Barsby's role is chief executive of NIAB, the National Institute of Agricultural Botany, located in Cambridge. Charmingly she remembered me from the summer research placement I did on wheat at NIAB in 2012 ( I remember crouching over the lab radio to hear Bradley Wiggins storm his way to Olympic gold). NIAB is the largest field trial operator in the UK, testing new varieties of both crops and ornamentals before they reach the commercial market. Her talk reiterated the challenge facing plant scientists to do more ( increase food production by 50% by 2030) with less ( water, fertiliser, energy inputs, etc) and described the role NIAB was playing in exploring the genetic potential of crop cultivars to meet this yield gap. I had no idea that crop yields could be quite so variable - although the current UK average for wheat yields is 7-8 tonnes per hectare, in some areas of the country ( such as the Cotswolds) this can reduce to 3-4 tonnes per hectare, whilst the world record is currently 15.6 tonnes per hectare ( achieved in New Zealand). Shockingly, unless the average wheat yield is significantly improved, we will need to cultivate an additional area of land equivalent to 24 United Kingdoms....one line of research being pursued at NIAB is to recreate the events that led to the development of modern wheat. originally, two wild gasses hybridised to produce Emmer Wheat, which later crossed with Wild Goats' Grass to form what we know now as 'modern wheat' ( see diagram below). Over time, much of the genetic diversity that resulted from these early events would have been lost as farmers repeatedly selected the highest yielding strains. To try and 'recreate' this genetic diversity, researchers are crossing Durum Wheat with Wild Goats' Grass (see below) with the hope that this will help to develop new cultivars. Early results suggest that one new cultivar may give yields up to 30 % higher, however this research is still in the first stages. Nevertheless, it was fascinating to hear from those who are directing the research to find the crops of the future.
A history of wheat and how this relates to modern efforts to increase food production
I always enjoy the formal dinners at Gatsby meetings - although they have the elegant presentation, wine, silverware, candles and waiter service, they are completely relaxed and don't require uncomfortable dressing up! Conversation flowed with topics leaping from the most inventive way to propose to ones fiancée, how the crusades shaped English history and how science should be delivered on the school curriculum.
There was no after dinner speaker this time but I was too tired to adjourn to the bar with the others so retired to my cosy college room, passing under the silver spring moon as it shone on the ancient arches in the cloisters...
Networking, discussing science... the food is very nice too!
Friday, 11 April 2014
Gatsby Training Weekend - Cambridge. Day 1
Oh to be in Cambridge, now that April’s
here! The sun seemed to shine with increasing warmth as my train journeyed
through increasingly flatter land. Although I have great affection for my new
home, Sheffield, the annual Gatsby Plants Training Weekend is an event I would happily
travel much further for. Sometimes, we plant scientists can feel as a minority
group in society, so it is wonderful to come together (in the protective
environs of Jesus College Cambridge) for encouragement, socialising and to
discuss fascinating science!
On arrival, I had time to pop into the
Sedgwick Museum of Earth Sciences to admire the ancient Lepidodendron
fossils from the Carboniferous period. In the absence of flowering plants and
'modern' trees, the horsetails were the dominant form of vegetation, unlike
today where they are often treated as an after though in the plant kingdom. I
always enjoy peering at the scale- like depressions on these relics that mark
where early leaves would have attached and the circular scars left by former
rootlets. Ghosts of the past, these call us to pay homage to how plant form and
function has stood the test of time. I then took a short excursion to the
Whipple Museum, a little- known collection of historical scientific instruments
and teaching aids. I am intrigued at the sense of artistry often found
associated with old scientific instruments, which seems absent in the mass
produced, anonymous tools of today. Here, I could admire beautiful anatomical
models, each one a delicate work of craftsmanship, sextants and astronomical
devices with painstakingly worked engravings, microscopes worked out of glowing
brass.... And yet perhaps there is a resurgence in pairing science with art.
Microscopic images, be they of bugs, diseases or pollen grains, frequently
feature in national newspapers and scientists are increasingly engaging in
alternative visual methods to demonstrate their science. In the Wellcome Collection
in London , for instance, the human genome is reprinted as a series of books...
a very powerful image of how much 'code' each of our cells packs inside the
nuclues! The very fact that you can now buy 'toy' microbes and diseases ( see http://www.giantmicrobes.com/uk/)
demonstrates that science is an embedded feature of popular modern culture!
A historical device used to measure transpiration ( water loss ) from plant leaves ... Not what I would call very portable! From the Whipple Museum, Cambridge
A teaching aid showing a ' typical ' animal cell, Whipple Museum, Cambridge.
I couldn’t distract myself for too long however as I had to settle into “scientific presentation mode”. Each PhD student had been asked to prepare an 8 minute powerpoint presentation on their projects, to be followed by 4 minutes for questions. I was hoping that I would score some “novelty” points for working on parasitic plants but worried that I would be confronted with technical enquiries that were out of my depth (4 minutes is a long time to be interrogated!). I barely had time to drop my bag off in my room and grab a cup of tea before we launched into the talks.
If I had been doing my project in he 1960s, I might have used one of these instead of a mass spectrometer! This 'Electron Microbe' was then the most advanced method of determining the chemical components of a sample. In the column on the left, the sample would absorb energy from a bombardment of electrons, some of which would be re-emitted as x-rays. The energy and intensity of the radiation would depend on the composition of atoms in the sample, hence by measuring this, the chemicals in the sample could be determined.
It was intriguing to see the broad range of
topics we covered between us, whilst still remaining firmly embedded in the
plant sciences. Everything seemed to be represented – plant development,
symbioses with nitrogen-fixing Rhizobium bacteria, hormone gradients,
photosynthesis, algae, carnivorous plants… I was especially interested in Emily
Seward’s introduction to the “phantom parasite” Phytomonas – unicellular
organisms with a distinct corkscrew shape and flagellate tail. Their reference
to phantoms is due to the fact that it took scientists a long time to identify
these parasites as the causative agents of major plant diseases including cassava
root rot. This was partly due to Phytomonas occupying parts of the plant
– such as latex tissues and phloem vessels – not typically associated with
parasites. Interestingly, these organisms are kinetoplatids, belonging to the
family Trypanosomes, whose members include the vectors behind more well known
human diseases, such as Chagas disease and sleeping sickness. Emily’s talk was
inspiring and I am certainly keen to learn more about these parasites. To me,
it embodied what an ideal scientific presentation should do – introduce the
audience to a new area of science that leaves them hungry for more!


Recognise me? One of the reasons I have great affection for Jesus College Cambridge, is the statue in the front courtyard (left). Anyone who has seen my Facebook Profiles will know that I have a slight obsession with the city of Venice and this sculpture is modeled on the Horses of St Mark's Basilica (right), originally looted from Constantinople. Technically, there should be four horses striding across the lawns at Jesus College but I find it so charming to have even this Byzantine influence from across the Adriatic... if I ever win the lottery, I shall commission a set for my garden!
I was disappointed with my talk, both with my delivery ( stumbling over the odd word) and how I handled the questions ( I realise that I could improve my knowledge on the more technical details of MALDI-MS). At least I managed to get the words out although I was extremely put off when I realised that we were being filmed! My strategy for giving presentations is to try and learn my words by rote but I do worry that this makes me sound too 'mechanical'. As though I am not even interested in what I am speaking about. ( and nothing could be further from the truth!). Certainly the most engaging speakers this afternoon had a natural style and gave the impression that they could talk about their work at any time, in any setting as they were so familiar and comfortable with it. A level to aspire to, in my case! As mine was the last talk, everyone's thoughts are probably already on dinner, a formal three course meal we enjoyed in the upper hall.
The after dinner speaker was Michael Akam, a developmental biologist whose papers on Hox genes I remember studying for my final year undergraduate exams. Through his own diverting career he was able to give some sage advice to the assembled PhD students. Mainly, to KEEP GOING and accept that there will be weeks at a time when nothing will seem to go right. It is all very well to get the interesting result you were hoping for but to replicate it is quite another thing again! He also encouraged us to make sure we chose an area we had a real attraction to : there is no point investigating an answer to a question that we are not personally interested in answering. Meanwhile, he also emphasised how important it is to capture the imagination if others with your science. He pointed out that palaeontology never ceases to attract funding, despite the fact that studying dinosaurs could have little 'useful' application in the modern age. I think Jurassic Park has a lot to answer for this!
Although the stream of questions showed no sign of abating, at half past none, it was decided to adjourn to the bar. As for me, I headed to my lovely college room to try and get some rest for tomorrow
I was disappointed with my talk, both with my delivery ( stumbling over the odd word) and how I handled the questions ( I realise that I could improve my knowledge on the more technical details of MALDI-MS). At least I managed to get the words out although I was extremely put off when I realised that we were being filmed! My strategy for giving presentations is to try and learn my words by rote but I do worry that this makes me sound too 'mechanical'. As though I am not even interested in what I am speaking about. ( and nothing could be further from the truth!). Certainly the most engaging speakers this afternoon had a natural style and gave the impression that they could talk about their work at any time, in any setting as they were so familiar and comfortable with it. A level to aspire to, in my case! As mine was the last talk, everyone's thoughts are probably already on dinner, a formal three course meal we enjoyed in the upper hall.
The after dinner speaker was Michael Akam, a developmental biologist whose papers on Hox genes I remember studying for my final year undergraduate exams. Through his own diverting career he was able to give some sage advice to the assembled PhD students. Mainly, to KEEP GOING and accept that there will be weeks at a time when nothing will seem to go right. It is all very well to get the interesting result you were hoping for but to replicate it is quite another thing again! He also encouraged us to make sure we chose an area we had a real attraction to : there is no point investigating an answer to a question that we are not personally interested in answering. Meanwhile, he also emphasised how important it is to capture the imagination if others with your science. He pointed out that palaeontology never ceases to attract funding, despite the fact that studying dinosaurs could have little 'useful' application in the modern age. I think Jurassic Park has a lot to answer for this!
Although the stream of questions showed no sign of abating, at half past none, it was decided to adjourn to the bar. As for me, I headed to my lovely college room to try and get some rest for tomorrow
Wednesday, 9 April 2014
Fuelling the Future
Biofuels…the saviour of the energy crisis? Or a curse that
diverts food resources from the needy?
Scientists are well aware of the arguments against using
plant material to fuel the future. Current research is responding to this by
investigating how the “non-foody” bits of plants – the dry matter called
lignocellulose – could be converted into the next generation of biofuels. The
problem is that this material was designed for strength and durability – think
of a giant redwood’s canopy towering above the forest floor –not for rapid
breakdown into a combustible fuel. This has led to two approaches:
- Developing plants whose cell walls are more easily digestible WITHOUT compromising field performance
Or
- Finding novel enzymes that allow a more effective pre-treatment.
These avenues of research are
being coordinated by a new initiative: This: Meanwhile, Simon McQueen-Mason
(University of York) described his research on a curious organism, the marine
wood borer Limnoria (also known as “the gribble”). Most animals,
including cows and rabbits, rely on bacteria in their guts to supply the
enzymes necessary to break down tough plant material, yet Limnoria is
unusual in that it has a completely sterile gut… hence it must manufacture
itself the enzymes it uses to bore holes into wooden boats. These include the
glycosyl hydrolase GH7 – more commonly found in filamentous fungi, Limnoria
is the first known animal to possess it. The enzyme specific to the wood borer,
however, has very high stability to salt – an adaption to the marine
environment. An additional quirk is that the enzyme for Limnoria attacks
the crystalline arrays of cell wall compounds, rather than the non-crystalline
parts that would be easier to digest. This suggests that Limnoria targets
wooden materials specifically to obtain glucose. It may be that the borer does
not possess any enzymes for the non-crystalline hemicellulose material. Researchers
have also found, however, that even before the ingested wooden material reaches
the gribble gut with its arsenal of enzymes, it is subjected to a special
“pre-treatment” to loosen the structure before digestion. This is achieved
using a specific chemical secreted by a gland called the hepatopancreas.
Besides reducing the need for bacterial enzymes, this organ also stores toxins
released from the wood, preventing them from reaching the gut.
So how could this knowledge be
used to keep us on the move in the future? Scientists are hoping to sequence
the genes encoding the gribble enzymes in order to introduce them into bacteria,
allowing mass-scale production. The pre-treatment process that the gribble uses
meanwhile, could help develop new ways of preparing lignocellulose material for
biofuel production that don’t require the prohibitively high temperatures
currently used.
Peter Eastmond (Rothamsted
Research), meanwhile, described the research efforts focused on diverting
vegetable oil production away from oil palm, currently the highest yielding
terrestrial oil crop but also the cause of large scale rainforest destruction
to clear ground for plantations. Seeds, with their high content of lipids
(especially triacylglycerides), are an incredibly dense source of vegetable oil,
with this accounting for up to 70% of seed dry weight. As a result, oilpalm,
soybean and rapeseed are favoured for biodiesel production. The proportion of
the plant made up of seeds however, is relatively small, especially compared with
the amount of woody/ lignocellulose material.
The woody material of Miscanthus grass, meanwhile, can be used to
make bioethanol, although this material only contains approximately 0.1% of
vegetable oil in dry weight. If Miscanthus could be engineered to
convert 20% of its biomass into oil, it could produce a yield seven times that
of rapeseed in terms of biofuel production. Besides growing rapidly and being
very hardy, these grasses can be grown in Europe, thus potentially saving
tropical regions from being converted into biofuel plantations. This won’t be possible using traditional
plant breeding (selecting the strains with the highest natural oil content and
breeding these together) but will require completely re-engineering the
cellular metabolism. Preliminary work on the model organism Arabidopsis
(thale cress) has demonstrated that introducing certain combinations of genes
CAN increase the oil content of vegetative tissues by up to 400 times… the
challenge now is to repeat the process in a suitable crop plant for industrial
applications. In the Arabidopsis system, oil accumulation was
particularly enhanced when the gene SUGAR-DEPENDENT 1 was switched off –
this seems to be responsible for oil breakdown. Hopefully, these exciting
findings can be used to develop crops that can satisfy our need for fuels
without compromising tropical biodiversity or global food security.
For more information about the
work being done use gribble enzymes in biofuel production, see the BBSRC
article here: http://www.bbsrc.ac.uk/news/industrial-biotechnology/2012/121128-f-meet-the-gribbles.aspx .
To read more about the work on Miscanthus, see http://www.bbsrc.ac.uk/news/industrial-biotechnology/2013/130521-pr-turning-leaf-into-biodiesel-factory.aspx.
Saturday, 5 April 2014
EXPLOSIVE Plant Science!
Although typically associated
with developing enhanced food crops, GM technology has a wealth of potential
applications. One of the most inspiring talks (to my mind at least) at the UK
PlantSci conference was that of Elizabeth Rylott (University of York): “Plant
Cillit Bang! And the dirt is gone! Using TNT to understand detoxification of
organic pollutants by plants”. Trinitrotoluene (TNT), a potent carcinogen, is a
pollutant released from explosive materials and which contaminates
approximately 10 million hectares in the USA (especially around military
zones), poisoning groundwater sources. Plants are naturally able to detoxify
low levels of TNT, using enzymes which “activate” the functional groups on TNT.
This then allows enzymes called uridine diphosphate (UDP) glycosyltransferases
(UGTs) to transfer the activated groups to an acceptor molecule, converting TNT
into a less toxic compound. Transgenically
over-expressing these enzymes can reduce the levels of TNT in plants grown on
contaminated soil. A problem, however, is that TNT often occurs in nature
alongside cyclotrimethylenetrinitramine (RDX), which plants cannot detoxify. Nevertheless,
RDX detoxifying enzymes have been identified in bacteria, including a
cytochrome p450 monoxygenase in Rhodoccocus. When this is introduced
into plants already engineered for enhanced TNT detoxification, the result is “super
plants” capable of restoring contaminated soil. Such “bioremediation”
strategies are becoming increasingly popular and could play a part in turning
public opinion in favour of GM. Indeed, these plants were capable of removing
all RDX from the surrounding soil within a week. Rather than just accumulating
toxic RDX in the leaves, however, these plants convert it into a source of
nitrogen – which they then use to fertilise their own growth! Hence, RDX does
not simply move from the soil to the plant, but is converted into a completely
harmless form.
Professor Elizabeth Rylott and her amazing transgenic switchgrass
So could this be a message of hope to those millions of
devastated acres tainted with explosives? Excitingly, this research has now
moved to the field trial stage in the USA, using transgenic switchgrass.
Amusingly, part of the preparations for these trials involved packaging the
seed into soil plugs and dropping these off the roof of the lab… apparently,
the military strategy for planting the transgenic plants will be to drop them
from a helicopter, hence the team had make sure the plants could stand up to
this treatment!
A crucial experiment...making sure the seed plugs can survive the impact of being dropped by a helicopterAnd just in case you were wondering... the above is all true and NOT an April Fool!
UK PlantSci 2014 conference - Day 2: Tuesday 1st April
Day two and another early start in the name of plant science.... I had worried that I wouldn't get much sleep I the shared dorm at the youth hostel but with only two other ladies in the room, it was pleasantly quiet!
The first set of sessions centred on the theme 'Environment, diversity and adaptation'. Tina Sarkinen, of the Royal Botanic Garden in Edinburgh gave a fascinating introduction to life in the Andes, where plants have to be incredibly resilient to survive in a land where the climate can vary between that the extremes of North Africa and Greenland. Clearly, Peru is a hotbed of diversity and an estimated 29% of the plants and animals that remain undiscovered will be found here. Meanwhile, I was pleased to pleased to finally meet Sebastian Schornack of the ( brand spanking new) Sainsbury Laboratory in Cambridge, who works on filament out plant pathogens and with whom I once applied to do a PhD with. His presentation focused on the devastating pathogen Phytophthora palmivora: his belongs to a distinct, and little known, class of fungal like organisms called oomycetes. Clearly however, there is a pressing need for greater knowledge of this genus, which is responsible for a wide range if plant diseases, including ash dieback and potato blight. Over coffee, I engaged in a spot of 'networking' to raise the possibility of some collaborative work to compare the response of host plants to parasitic plants ( such as Orobanche ) and the Phytophra oomycete... Watch this space!
The second session, 'Plants as Factories', presented a fascinating mix of pioneering research seeking to encourage the production of desirable compounds and chemicals in plants. This included anthocyanin production in blood oranges. These cancer fighting compounds are specifically found in blood oranges ( as opposed to 'blonde' oranges) however these can only be cultivated in certain regions, such as Sicily, as they require a cold period to develop their distinct colour. Blood oranges have recently garnered interests through studies which suggest their juice could be an aid to weight loss: mice fed on a high fat diet gain less weight when given blood orange juice to drink, compared with standard orange juice. As such, there is great interest in introducing the anthocyanin- producing trait into more easily cultivated orange species. Cathie Martin, of the John Innes Centre, described the progress made so far in identifying genes responsible for anthocyanin production. I was also able to hear a first hand account of the development of omega-3 fatty acid producing oilseed crops ( see the previous post 'Something Fishy...') from Jonathan A. Napier from Rothamsted Research. This was followed by Simon McQueen-Mason's (University of York) account of the various approaches being made to engineer crops more suitable for use as biofuels (see the post 'Fuelling the Future'). After the depressing start yesterday, I was feeling much more inspired and invigorated!
It was even sunny enough to enjoy a buffet lunch out on the waterfront, in the company of the resident ducks and geese. Then the final session, which described some of the various new technologies being introduced into plant science. These included a CT scanning method being developed at the Centre for Plant Integrative Biology ( University of Nottingham) to map root architecture non- invasively. The closing speech was delivered by Jackie Hunter, Chief Executive of the funding body BBSRC (Biological and Biomedical Sciences Research Council) who stressed the organisation's commitment to developing world-leading plant science in the UK. Then a flurry of activity as cases were snatched up, coats collected, feedback forms handed in.... We may enjoy getting together but plant scientists are generally busy people! As the crowd dispersed, I paused to reflect on the hundreds of fascinating avenues of research we represented collectively, and to which we would return with renewed excitement.
The start of the next session is imminent...
Friday, 4 April 2014
UK PlantSci 2014 conference - Day 1: Monday 31st March
Associated with a beautiful Minster, Richard III, Rowntrees
Fruit Pastilles…and now world leading plant science! My excitement mounted as I
browsed the programme of the UK PlantSci conference – “Plant Science –
sustaining life on earth” – on the train. Fortunately, York is only a short hop
from Sheffield so arriving in good time to register at 10.00 wasn’t too
uncomfortable.
I feel so much more professional with an official badge!
The first series of talks set a depressing forecast for the
future. With the global population expected to reach 9 billion by 2050, and
with changing diets in developing countries to take into account, agricultural
production will need to step up by at least an additional 60%. This challenge –
considerable in itself – also faces the hurdles of sustaining biodiversity,
conserving diminishing water sources, lowering nutritional inputs and coping
with a more irascible climate. It seems there has never been a time when plant
scientists have been needed more…
A key point, however, was that food security is about much
more than food production but also access and management. As
up to a third of food is lost as waste and obesity costs the NHS billions each
year, it is clear that there are staggering discrepancies in food availability.
Addressing these issues alone could achieve some progress. In addition,
everybody could “do their bit” by resolving to eat fewer meat and dairy
products. If one person decides to forgo just one burger a week, over a year
this would save the equivalent in Green House Gas emissions as taking a car off
the road for 320 miles. Food for thought indeed…. yet there is still the need
for innovative science, particularly as our climate is already changing. Sadly,
it seems that we are definitely on course for a world which is 4 degrees
warmer. Although this may not sound so much in itself, the main problem from an
agricultural point of view is that weather variability will also
increase. This directly impacts crop
yields; for instance, although the UK average yield for wheat is 8 tonnes per
hectare, this could diminish to 2-3 tonnes per hectare in some years. Not just “a
bad year for farmers” but a stressful time for consumers – imagine it;
staggering prices in the supermarket, customers fighting over loaves of bread…it
is little wonder that civil unrest correlates with food prices.
So…plant science to the rescue!!??
Several of the talks on the first day focused on the
challenge of “doing more with less” – particularly regarding water use. Adam
Price, of the University of Aberdeen, described the pioneering technique of “Alternate
Wetting and Drying” for rice. This water-saving technique involves alternately
flooding rice plants, rather than keeping them constantly inundated. Water
levels are monitored by means of a “field water tube” – when the water level drops to a
certain point, the field is “topped up” with pond water. Besides saving up to
30% of water inputs, for some cultivars this method can actually increase
yields by up to 33%. An innovative, practical solution…and cheap!
Meanwhile, Carla Turner of the University of Sheffield
described how water use efficiency could also be improved by manipulating the
number of stomata; the pores on leaves which enable gas exchange but are also
the main route of water loss. Key regulators in stomatal development have been
identified and over expressing these can lead to fewer stomata and plants that
thrive on low moisture regimes.
Other talks addressed the problem of plant diseases, which
claim 40% of global food production (before we waste a third of it!). A
particular worry is how plant pathogens will be affected by climate change and
whether we can expect diseases to broaden their range to encompass more growing
regions. There was discussion on using climate forecast modelling to predict
disease movements and a clear call to implement greater monitoring schemes,
particularly in developing countries.
It is shocking how the global agricultural system has come
to depend on such a limited range of crops. In an increasingly variable world,
it is likely that new “star players” will emerge as the crops of the future.
One candidate is Sorghum, a highly drought resistant grain and forage crops.
Presidor Kendabie, however, the University of Nottingham, turned our attention
to the bambara groundnut, a tropical legume. Advantages include an ability to
fix nitrogen, drought tolerance and a good range of amino acids. In addition,
although similar to the peanut, this species contains no allergens. A
convincing contender for the supermarket shelves of the future…
A busy day of talks and still more to come! But first, an
overnight breather to try and take it all in so far.
Posters and trade stands (freebies) in the atrium