Synthetic biology in chloroplasts

Dr Anil Day, University of Manchester

Dr Anil Day, University of Manchester

This week we spoke to Dr. Anil Day, a synthetic biologist at the University of Manchester who has developed an impressive array of tools and techniques to transform chloroplast genomes.


Could you begin by giving our readers a brief overview of synthetic biology?

Synthetic biology involves the application of engineering principles to biological systems. One approach to understanding a biological system is to break it down into smaller parts, which can be used to design new properties. These redesigned pieces can be reassembled into a new system, tested experimentally, and refined in an iterative process. Synthetic biology projects that are underway in our lab include designing plastids such as chloroplasts with new metabolic functions, and in the longer term the design and assembly of synthetic chloroplast genomes.


Anil Day examines transformed plants

Dr. Anil Day examines a cabinet of transformed plants. Credit: Dr. Anil Day.

Why do you use chloroplasts for synthetic biology systems?

Chloroplasts have a relatively small genome, coding for about 100 genes. Importantly, exogenous (foreign) genes coding for new functions can be precisely introduced into the chloroplast genome. All of the plastids within a plant contain the same genome so, once established, the user-designed reprogrammed plastids will be present throughout the plant. Chloroplasts can also produce very high levels of protein; researchers have achieved expression levels where over 70% of the total soluble protein in the leaves is the engineered protein. Expression in tomato fruit is also possible.

Multiple genes can be introduced into chloroplasts and expressed coordinately, allowing the metabolic engineering of more complex processes. The upper size limit for insertions is not known but is likely to be above the 50,000 nucleotide insertion achieved to date. Furthermore, chloroplasts and other plastids are important metabolic hubs and contain a wide variety of chemical substrates useful for metabolic engineering.

Plastids in plants

Plants have several types of plastids, including green photosynthetic chloroplasts, pigment-containing chromoplasts, and starch-containing amyloplasts. Credit: Dr. Anil Day.


Could you describe the current state of our ability to engineer chloroplasts?

Chloroplast engineering is routine in many labs around the globe. Although there are multiple chloroplasts in every cell, the process of converting all the chloroplasts to a single population of engineered genomes is not an issue. Most researchers use the tobacco plant because it is easily transformed, but other crops are amenable to transformation, including oilseed rape, soybean, tomato, and potato (cereals such as rice and wheat are more problematic). There has been progress with developing the inducible expression of exogenous genes in chloroplasts too.


What challenges/differences do you face when transforming chloroplast genomes when compared to the nuclear genome?

Typical genetic modification of the DNA in the nucleus is performed by introducing exogenous genes in T-DNA. T-DNA is transferred to the plant using the bacterium Agrobacterium tumefaciens, which is an efficient process, but the T-DNA integrates ‘randomly’ at many sites within chromosomes and different lines can have variable expression levels due to positional effects and gene silencing.

A. tumefaciens-mediated gene delivery systems do not work for chloroplast transformation. Most chloroplast transformation labs introduce genes into plastids by blasting cells with gold or tungsten particles coated with DNA. Because chloroplast genomes are present in multiple copies per cell, the process of converting all resident chloroplasts to the transgenic genome requires a continued period of selection. This means that the isolation of chloroplast transformants can take slightly longer than nuclear transformation. In our lab, we speed up this process by using restoration of photosynthesis to select chloroplasts with exogenous genes. Once plants with a uniform population of transgenic plastid genomes have been isolated, the transgenes are stable and inherited through the maternal line.

For the novice, I would say nuclear transformation using A. tumefaciens is easier to accomplish than chloroplast transformation.


Edited chloroplasts

A tobacco plant containing leaf areas with edited (pale green) and normal (darker green) chloroplasts. Credit: Dr. Anil Day.

Last year you reported that chloroplasts degrade in mature sperm cells just prior to fertilization. Could you elaborate on how this might be utilized in future crop breeding?

Chloroplasts are inherited from the female parent in wheat. This is useful because it restricts the pollen-mediated spread of chloroplast-localized transgenes into the environment. Previously, no-one had studied the mechanism of maternal chloroplast inheritance in wheat using modern cell biology tools. With our collaborators Lucia PrimavesiHuixia Wu, and Huw Jones at Rothamsted Research, we developed an efficient method to observe small non-green plastids in wheat pollen in real time. We found that the plastids were destroyed during the maturation of sperm cells, which explained the absence of paternal plastids in the offspring.

This discovery has applications in crop breeding. Anther culture is a powerful technique where new homozygous plants can be produced by doubling the chromosome numbers of haploid plants regenerated from pollen. This technique has been challenging in cereals, as chloroplast degradation in pollen leads to a high percentage of albino plants (in some cases 100% albinos). Understanding how to prevent the destruction of plastids in pollen sperm cells will improve this technique in cereals, which could speed up crop breeding in the future.


Selection of transformed plants

Transformed plantlets are selected by their ability to survive on a herbicide-containing agar plate, and can then be grown up into mature plants. Credit: Dr. Anil Day.

 What sorts of processes have you successfully transformed into chloroplasts, and what kinds of results have you achieved?

We have expressed a variety of exogenous genes in chloroplasts, from those conferring resistance to herbicides to vaccine epitopes and pharmaceutical proteins:

  • Plants expressing the bar gene in chloroplasts were resistant to the herbicide glufosinate (also known as phosphinothricin).
  • A chloroplast-expressed viral epitope was used to identify samples of human blood infected with the hepatitis C virus.
  • Human transforming growth factor 3 (hTGFβ3), a potential wound healing drug, accumulated to high concentrations in chloroplasts, and could be processed to a pure active form resembling clinical grade hTGFβ3.
  • In collaboration with Ray Dixon, Cheng Qi, and Mandy Dowson-Day at the John Innes Centre, we investigated the feasibility of introducing nitrogen-fixing genes into chloroplasts. This work was initiated in a unicellular green alga with the bacterial nifH gene.


What is the cutting edge of chloroplast transformation research?

Chloroplast genes are important for plant growth and development but they are difficult to improve by conventional breeding methods. We recently developed a method to edit plastid genomes, which allows beneficial single point mutations to be introduced into chloroplast genes. This is important because the resulting plants have an identical genome to the original cultivar apart the single base substitution, potentially leading to a new class of biotech crop.

Registration open for GPC/SEB New Breeding Technologies Workshop!

New Breeding Technologies in the Plant Sciences – Applications and Implications in Genome Editing

Gothenburg, Sweden, 7-8th July 2017


Organised by: Dr Ruth Bastow (Global Plant Council), Dr Geraint Parry (GARNet), Professor Stefan Jansson (Umeå University, Sweden) and Professor Barry Pogson (Australian National University, Australia).

Targeted genome engineering has been described as a “game-changing technology” for fields as diverse as human genetics and plant biotechnology. Novel techniques such as CRISPR-Cas9, Science’s 2015 Breakthrough of the Year, are revolutionizing scientific research, allowing the targeted and precise editing of genomes in ways that were not previously possible.

Used alongside other tools and strategies, gene-editing technologies have the potential to help combat food and nutritional insecurity and assist in the transition to more sustainable food production systems. The application and use of these technologies is therefore a hot topic for a wide range of stakeholders including scientists, funders, regulators, policy makers and the public. Despite its potential, there are a number of challenges in the adoption and uptake of genome editing, which we propose to highlight during this SEB satellite meeting.

One of the challenges that scientists face in applying technologies such as CRISPR-Cas9 to their research is the technique itself. Although the theoretical framework for using these techniques is easy to follow, the reality is often not so simple. This meeting will therefore explain the principles of applying CRISPR-Cas9 from experts who have successfully used this system in a variety of plant species. We will explore the challenges they encountered as well as some of the solutions and systems they adopted to achieve stably transformed gene-edited plants.

The second challenge for these transformative technologies is how regulatory bodies will treat and asses them. In many countries gene editing technologies do not fit within current policies and guidelines regarding the genetic modification and breeding of plants, as it possible to generate phenotypic variation that is indistinguishable from that generated by traditional breeding methods. Dealing with the ambiguities that techniques such as CRISPR-Cas9 have generated will be critical for the uptake and future use of new breeding technologies. This workshop will therefore outline the current regulatory environment in Europe surrounding gene editing, as well as the approaches being taken in other countries, and will discuss the potential implications and impacts of the use of genome engineering for crop improvement.

Overall this meeting will be of great interest to plant and crop scientists who are invested in the future of gene editing both on a practical and regulatory level. We will provide a forum for debate around the broader policy issues whilst include opportunities for in-depth discussion regarding the techniques required to make this technology work in your own research.

This meeting is being held as a satellite event to the Society for Experimental Biology’s Annual Main Meeting, which takes place in Gothenburg, Sweden, from the 3–6th July 2017.

RNA clay offers green alternative to plant pesticides

By Neena Bhandari

A nano-sized bio-degradable clay-comprising double stranded ribonucleic acid (dsRNA) could offer a cost-effective, clean and green alternative to chemical-based plant pesticides.

Australian researchers from the University of Queensland have successfully used a gene-silencing spray, named BioClay, a combination of biomolecules and clay, to protect tobacco plants from a virus for 20 days with a single application. Their study has been published in Nature Plants.

“When BioClay is sprayed onto a plant, the virus-specific dsRNA is slowly released from the clay nanosheets into the plant. This activates a pathway in the plant that is a natural defence mechanism. The dsRNA is chopped up into small bits of RNA by enzymes of this pathway. These small bits attack the virus when it infects the plant without altering the plant genome,” explains lead researcher, Neena Mitter.

“Even with current pesticides, we lose up to 40 per cent of our crop productivity because of pests and pathogens. We are hoping that having BioClay in the mix as an environmentally friendly, sustainable crop protection measure will reduce crop losses,” Mitter adds.

“The clay-based delivery technology could represent a positive inflection point in the progress towards commercialisation of topical RNAi. This is a non-GM, environmentally benign and very specific technology.”

 John Killmer, APSE

While chemical-based pesticides kill the targeted insect, they can also affect a range of other insects that are beneficial. Mitter says, “BioClay is specific and it only kills the pathogen being targeted. Currently farmers use insecticides to kill the vector that comes with the viruses, but with BioClay we can target the virus itself.”

BioClay field trials may begin in Australia by year-end. “The first test will be on a virus that infects vegetable crops — capsicum, tomato, chilli,” Mitter tells SciDev.Net.

Farmers can use the existing equipment to deliver BioClay and the researchers are hopeful that it will be a commercially viable product for farmers everywhere. The clay component is cheap to make, but not the RNA.

Several companies like APSE, a US based startup, are working on the mass production of RNAs. APSE is developing RNA manufacturing technology for RNA interference (RNAi) or gene silencing applications.

“Our technology for RNA production should be ready in 2-3 years. We are targeting US$2 per gram,” APSE’s John Killmer tells SciDev.Net.

Killmer says, “The clay-based delivery technology could represent a positive inflection point in the progress towards commercialisation of topical RNAi. This is a non-GM, environmentally benign and very specific technology.”

RNAi technology is being used by many in the agriculture industry including the biotech firm Monsanto. The company’s BioDirect technology is focused on applications of RNAi directly onto the leaves of a plant.

Monsanto’s spokesperson John Combest tells SciDev.Net, “As insects develop resistance to certain classes of pesticides, giving farmers another option to control these pests is critical. The idea is not to replace any given system of farming, whether modern GM systems or others — it’s to provide farmers with products that can complement or replace agricultural chemical products.”

This piece was produced by SciDev.Net’s Asia & Pacific desk.


This article was originally published on SciDev.Net. Read the original article.

Plant Artificial Chromosome Technology

Established GM technologies are far from perfect

The first genetically modified (GM) crops were approved for commercial use in 1994, and GM crops are now grown on over 180 million hectares across 29 countries. The most used forms of genetic modification are systems that result in herbicide resistance or expression of the Bt toxin in maize and cotton to provide protection against pests such as the European corn borer. These systems both require few novel genes to be introduced to the plant, and allow more efficient use of herbicides and pesticides, both of which are harmful to the environment and human health. Current systems of genetic modification usually involve

Agrobacterium tumefaciens is used to genetically engineer plants in the lab. In nature this bacteria uses its ability to alter plant DNA to cause tumours.

Agrobacterium tumefaciens is used to genetically engineer plants in the lab. In nature this bacteria uses its ability to alter plant DNA to cause tumours. Image by Jacinta Lluch Valero used under Creative Commons 2.0.

the use of Agrobacterium vectors, direct transformation by DNA uptake into the plant protoplast, or bombardment with gold particles covered in DNA. However, current systems of transformation are far from perfect. Many beneficial traits such as disease resistance require stacking of multiple genes, something that is difficult with current transformation systems. Furthermore, it is essential that transgenes are positioned correctly within the host genome. Current systems of genetic modification can insert genes into the ‘wrong’ place, disrupting function of endogenous genes or having implications for down or upstream processes. An additional problem is that transfer of transgenes from one line to another requires several generations of backcrossing. However, the past two decades have seen great developments in microbiology. Many new tools and resources are now available that could greatly enhance the biotechnology of the future.


New technologies

Many new and emerging technologies are now available that could transform plant genetic engineering. For example, high throughput sequencing and the wide availability of bioinformatics tools now make identifying target genes and traits easier than ever. Technologies such as site-specific recombination (SSR) and genome editing allow specific regions of the genome to be precisely targeted in order to add or remove genes. Artificial chromosome technology is also part of this emerging group that could be of benefit to plant science. Synthetic chromosomes have already been used in yeast, and widely studied in mammalian systems due to their potential use in gene therapy. Although there have so far been no definitive examples in plants, work has been done in maize that shows the potential of the technology for use in GM crops.


Building an artificial chromosome

A minichromosomes is a small, synthetic chromosome with no genes of its own. It can be programmed to express any desirable DNA sequence that could encode for one, or a number, of genes. An ideal minichromosome would be small and only contain essential elements such as a centromere, telomeres and origin of replication. Once introduced into the plant the minichromosomes should be designed such that interference with host growth and development is minimal. A key requirement is that the chromosome is stable during both meiosis and mitosis. This would ensure introduced genes do not become disrupted or mutated during cell division and reproduction. Gene expression would therefore remain the same for many generations. Finally, the DNA sequence on the minichromosomes could be designed such that it is amenable to SSR or gene editing systems. This would allow re-design and addition of new traits further down the line.


Potential advantages of artificial chromosomes

Plant artificial chromosomes (PACs) have many advantages over traditional transformation systems. For example, to confer complex traits such as disease resistance and tolerance to abiotic stresses such as heat and drought, multiple genes are required. This is not easy with current methods of modification.

PACs could offer a new way to introduce beneficial traits to our crops plants and feed a growing population.

PACs could offer a new way to introduce beneficial traits to our crops plants and feed a growing population.Image by Seattle.Romer. Used under Creative Commons 2.0.

However, PACs allow an almost unlimited number of genes to be integrated into the host system. A further possibility that comes from being able to add multiple genes is the addition of new metabolic pathways into the plant. This could allow us to change the nutrients produced by a plant to benefit our diets. Additionally, in a contained environment, plants could be used as a cheap, sustainable way to produce pharmaceuticals. A second major benefit of PACs is that they avoid linkage drag. This is when a desirable gene is closely linked to a deleterious gene that acts to reduce plant fitness. Where this linkage is very tight even repeated backcrossing cannot separate out the genes. Design of new DNA sequences completely avoids this problem, and could allow us to select out detrimental traits from out crop plants.


Regulations for novel biotechnology

Emerging technologies pose new questions to policy makers regarding GM regulation. For example, the use of genome editing, whereby specific sites in the genome are targeted and modified, produces an end product with a phenotype almost identical to one that could be achieved through conventional breeding. This sets genome-edited crops apart from other transgene-containing GM material. For this reason many now argue that genome-edited crops ought not to come under current GM regulations. Much of this argument centres on whether or not to regulate the scientific technique used to produce a crop, or to regulate the end product in the field. For more information on genome editing including current regulations and consensus, see the links at the end of this article.


PACs pose a different set of problems entirely. Minichromosomes would be foreign bodies in the plant, and gene stacking within these introduces even more foreign genes than is possible with current technologies. This would require extensive assessment of both environmental and health effects prior to commercialization. Currently regulatory approval costs around $1-15 million per insertion into the genome. These heavy charges may discourage the further development of minichromosomes technology. However, with PACs it is possible that a particular package of genes could be assessed once, and then transferred into numerous cultivars. This would eliminate the requirement to individually engineer and test every cultivar, so perhaps saving time and money in the long term.


More information on genome editing:

Sense about science genome editing Q & A

The regulatory status of genome-edited crops

The Guardian article on genome editing regulation

A proposed regulatory network for genome edited crops in Nature

A recent workshop on the CRISPR-CAS system of genome editing was held in September 2015 by GARNet and OpenPlant at the John Innes Centre in Norwich, UK. You can read the full meeting report here.












Now That’s What I Call Plant Science 2015

With another year nearly over we recently put out a call for nominations for the Most Influential Plant Science Research of 2015. Suggestions flooded in, and we also trawled through our social media feeds to see which stories inspired the most discussion and engagement. It was fantastic to read about so much amazing research from around the world. Below are our top five, selected based on impact for the plant science research community, engagement on social media, and importance for both policy and potential end product/application.

Choosing the most inspiring stories was not an easy job. If you think we’ve missed something, please let us know in the comments below, or via Twitter! In the coming weeks we’ll be posting a 2015 Plant Science Round Up, which will include other exciting research that didn’t quite make the top five, so watch this space!

  1. Sweet potato is a naturally occurring GM crop
Sweet potato contains genes from bacteria making it a naturally occurring GM crop

Sweet potato contains genes from bacteria making it a naturally occurring GM crop. Image from Mike Licht used under creative commons license 2.0

Scientists at the International Potato Center in Lima, Peru, found that 291 varieties of sweet potato actually contain bacterial genes. This technically means that sweet potato is a naturally occurring genetically modified crop! Alongside all the general discussion about GM regulations, particularly in parts of Europe where regulations about growing GM crops have been decentralized from Brussels to individual EU Member States, this story caused much discussion on social media when it was published in March of this year.

It is thought that ancestors of the modern sweet potato were genetically modified by bacteria in the soil some 8000 years ago. Scientists hypothesize that it was this modification that made consumption and domestication of the crop possible. Unlike the potato, sweet potato is not a tuber but a mere root. The bacteria genes are thought to be responsible for root swelling, giving it the fleshy appearance we recognize today.

This story is incredibly important, firstly because sweet potato is the world’s seventh most important food crop, so knowledge of its genetics and development are essential for future food supply. Secondly, Agrobacterium is frequently used by scientists to artificially genetically modify plants. Evidence that this process occurs in nature opens up the conversation about GM, the methods used in this technology, and the safety of these products for human consumption.

Read the original paper in PNAS here.

  1. RNA-guided Cas9 nuclease creates targetable heritable mutations in Barley and Brassica

Our number two on the list also relates to genetic modification, this time focusing on methods. Regardless of whether or not we want to have genetically modified crops in our food supply, GM is a valuable tool used by researchers to advance knowledge of gene function at the genetic and phenotypic level. Therefore, systems of modification that make the process faster, cheaper, and more accurate provide fantastic opportunities for the plant science community to progress its understanding.

The Cas9 system is a method of genome editing that can make precise changes at specific locations in the genome relatively cheaply. This novel system uses small non-coding RNA to direct Cas9 nuclease to the DNA target site. This type of RNA is small and easy to program, providing a flexible and easily accessible system for genome editing.

Barley in the field

Barley in the field. Image by Moldova_field used under creative commons license 2.0

Inheritance of genome modifications using Cas9 has previously been shown in the model plants, Arabidopsis and rice. However, the efficiency of this inheritance, and therefore potential application in crop plants has been questionable.

The breakthrough study published in November by researchers at The Sainsbury Laboratory and John Innes Centre both in Norwich, UK, demonstrated the mutation of two commercial crop plants, Barley and Brassica oleracea, using the Cas9 system and subsequent inheritance mutations.

This is an incredibly exciting development in the plant sciences and opens up many options in the future in terms of genome editing and plant science research.

Read the full paper in Genome Biology here.

  1. Control of Striga growth

Striga is a parasitic plant that mainly affects parts of Africa. It is a major threat to food crops such as rice and corn, leading to yield losses worth over 10 billion US dollars, and affecting over 100 million people.

Striga infects the host crop plant through its roots, depriving them of their nutrients and water. The plant hormone strigolactone, which is released by host plants, is known to induce Striga germination when host plants are nearby.

In a study published in August of this year the Striga receptors for this hormone, and the proteins responsible for striga germination were identified.

Striga plants are known to wither and die if they cannot find a host plant upon germination. Induction of early germination using synthetic hormones could therefore remove Striga populations before crops are planted. This work is vital in terms of regulating Striga populations in areas where they are hugely damaging to crop plants and people’s livelihoods.

Read the full study in Science here.

Striga, a parasitic plant. Also known as Witchweed.

Striga, a parasitic plant. Also known as Witchweed. Image from the International Institute of Tropical Agriculture used under creative commons license 2.0

  1. Resurrection plants genome harvesting

Resurrection plants are a unique group of flora that can survive extreme water shortages for months or even years. There are more than 130 varieties in the world, and many researchers believe that unlocking the genetic codes of drought-tolerant plants could help farmers working in increasingly hot and dry conditions.

During a drought, the plant acts like a seed, becoming so dry that it appears dead. But as soon as the rains come, the shriveled plant bursts ‘back to life’, turning green and robust in just a few hours.

In November, researchers from the Donald Danforth Plant Science Centre in Missouri, US, published the complete draft genome of Oropetium thomaeum, a resurrection grass species.

O. thomaeum is a small C4 grass species found in Africa and India. It is closely related to major food feed and bioenergy crops. Therefore this work represents a significant step in terms of understanding novel drought tolerance mechanisms that could be used in agriculture.

Read the full paper in Nature here.

  1. Supercomputing overcomes major ecological challenge

Currently, one of the greatest challenges for ecologists is to quantify plant diversity and understand how this affects plant survival. For the last 500 years independent research groups around the world have collected this diversity data, which has made organization and collaboration difficult in the past.

Over the last 500 years, independent research groups have collected a wealth of diversity data. The Botanical Information and Ecology Network (BIEN) are collecting and collating these data together for the Americas using high performance computing (HPC) and data resources, via the iPlant Collaborative and the Texas Advanced Computing Center (TACC). This will allow researchers to draw on data right from the earliest plant collections up to the modern day to understand plant diversity.

There are approximately 120,000 plant species in North and South America, but mapping and determining the hotspots of species richness requires computationally intensive geographic range estimates. With supercomputing the BIEN group could generate and store geographic range estimates for plant species in the Americas.

It also gives ecologists the ability to document continental scale patterns of species diversity, which show where any species of plant might be found. These novel maps could prove a fantastic resource for ecologists working on diversity and conservation.

Read more about this story on the TACC website, here.


Approaches to biofortification

Biofortification is the improvement of the nutritional value of our crops through both traditional breeding and genetic engineering. Alongside DivSeek and Stress Resilience, biofortification is one of the Global Plant Council’s three main initiatives and will be central to addressing many of the challenges facing world health. However, biofortification doesn’t always involve changing our crops in some way. Often the nutrients we are lacking are present in pre-existing crops. We can biofortify our diets simply by identifying what’s missing and altering our life style accordingly.

Tackling undernourishment

The share

The share (%) of undernourished people per country. From: Max Roser (2015) -‘Hunger and Undernourishment’. Published online at

More often that not we intuitively link biofortification with tackling undernourishment in the developing world, and indeed improvements in the diets of deprived communities would be of enormous benefit to global health.

To do this, a key challenge is to increase the nutrient content of staple food crops such as rice in Asia and maize in sub-Saharan Africa. We need to do this in a sustainable and affordable way; ensuring foods are accessible to those who need it. Alongside the fortification of staple crops we need to identify economical crop species that will grow in harsh environments and provide nutrients currently absent from the diet.

Addressing obesity

It is easy to forget that malnutrition is also a problem in developed countries. Worldwide, at least 2.8 million people per year die from obesity-related illnesses, and in 2011 more than 40 million children under the age of five were overweight. Obesity and related health problems such as diabetes, heart disease and certain cancers, place enormous strain on health services, and are partly a function of poor diet lacking in fibre and key phytonutrients. Addressing this is as important as tackling undernourishment, and many of the same principles apply.

Simple lifestyle changes, such as encouraging the consumption of more fruits and vegetables, are clearly a priority. In addition to this dietary change, if we are going to biofortify foods, there should be an emphasis on crops that are already widely consumed.

Purple tomatoes

Professor Cathie Martin

Professor Cathie Martin works at the John Innes Centre researching the link  between diet and health, and how crops could be fortified to improve our diets and global health.

Tomatoes, are one crop plant already eaten widely in the West, commonly found in fast and convenience foods. For this reason they became the focus of the work of Professor Cathie Martin at the John Innes Centre in Norwich, UK. Cathie’s lab has developed a genetically modified tomato that is rich in anthocyanins, making them purple in colour. Anthocyanins are an important dietary component that can have numerous health benefits, including a potentially significant role in the prevention of diseases such as cancer and diabetes. They are the compounds that give some foods, such as blueberries or eggplant, their distinctive blue or purple colouring. Consuming higher quantities could be highly beneficial to health.

“We focused on anthocyanins because of their huge potential health benefits. Pre-clinical studies show that introducing our purple tomatoes into the diet could be an incredibly effective way to protect against diseases such as cancer. Our next steps will be to confirm these findings in human trials,” says Cathie.

However, naturally occurring tomato varieties containing anthocyanins already exist. Wouldn’t it be better to increase consumption of these rather than creating new ones?

“Indeed purple tomatoes do occur naturally. However, these have anthocyanins only in the skin, in quantities too small to make a significant impact on health. Our genetically modified tomatoes have anthocyanins in all tissues,” explains Cathie.

Since developing the purple tomatoes, Cathie, in collaboration with Professor Jonathan Jones, has set up Norfolk Plant Sciences, the UK’s first GM crop company. However, resistance and uncertainty in Europe surrounding GM technology means that progress has been slow.

“The company was founded in 2007 and we are currently working towards the approval of our purple tomato juice in the USA. Producing just the juice rather than the entire fruit means there are no seeds in the final product. This eliminates environmental challenges without compromising health benefits. If the juice proves successful in the USA we may then work towards approval in the UK and Europe.”

It’s not all about Genetic Modification

Of course if we want to make drastic changes to our foods, such as increase anthocyanins in our tomatoes or carotenoids in our rice, GM technology will be a necessity. However, we can go some way to biofortifying our diets without the use of GM.

Golden rice

Golden rice, shown on the left, is a biofortified crop that accumulates high quantities of provitamin A in the grain. This could help tackle Vitamin A Deficiency in developing countries, from which 500,000 children become blind every year, and nine million will die of malnutrition. Photo credit: IRRI photos used under Creative Commons 2.0

Primarily we really need to focus on changing diet and lifestyle. Promoting plants rich in the nutritional components we need is essential, in addition to encouraging traditional diets such as the Mediterranean diet rich in fish, fruits and vegetables. However, changing people’s behavior and relationship with food is a huge challenge. Cathie cites the UK 5-A-Day governmental campaign as an example.

This campaign was aimed at encouraging people to eat five portions of fruit or vegetables a day. At the end of this 25-year campaign only 3% more of the UK population was getting their five a day.”

In addition to dietary change, we could biofortify our crops through traditional breeding. For example, one answer to increasing anthocyanins in the diet could be red wheat. Red wheat is rich in anthocyanins, and furthermore less susceptible to pre-harvest sprouting, which causes large crop losses every year for farmers. However, we have so far resisted selecting for this trait in wheat breeding programs as it is not considered esthetically pleasing. To improve our diets we may need to change our expectations of what we want our plates to look like.

Next steps

Plant scientists alone cannot tackle biofortification of our diets! Cathie believes the key to a healthier future is interdisciplinary research:

“Everyone needs to come together: nutritionists, epidemiologists, plant breeders, and plant scientists. However, with such a diverse group of people it is hard to reach agreement on the next steps, and equally as difficult to secure funding for research projects. We really need to promote collaboration and interaction between all groups in order to move forwards.”