Global Plant Council Blog

Plant Science for Global Challenges

Author: Amelia Frizell-Armitage (page 1 of 7)

1000 Plants

The 1000 plants initiative (1KP) is a multidisciplinary consortium aiming to generate large-scale gene sequencing data for over 1000 species of plants. Included in these species are those of interest to agriculture and medicines, as well as green algae, extremophytes and non-flowering plants. The project is funded by several supporters, and has already generated many published papers.

Gane Wong is a Professor in the Faculty of Science at the University of Alberta in Canada. Having previously worked on the Human Genome Project, he now leads the 1KP initiative. Dennis Stevenson, Vice President for Botanical Research, New York Botanical Garden, and Adjunct Professor, Cornell University (USA), studies the evolution and classification of the Cycadales. He became involved in the 1KP initiative as an opportunity to sample the breadth of green plant diversity.

We spoke to both Professor Stevenson (DS) and Professor Wong (GW) about the initiative. Professor Douglas Soltis from Florida Museum of Natural History also contributed to this blog post with input in editing the answers.

What do you think has been the biggest benefit of 1KP?

DS: This has been an unparalleled opportunity to reveal and understand the genes that have led to the plant diversity we see around us. We were able to study plants that were pivotal in terms of plant evolution but which have not previously been included in sequencing projects as they are not considered important economically

The 1KP project presented a fantastic opportunity to explore plant biodiversity. Photo by Bob Leckridge. Used under Creative Commons 2.0.

The 1KP project presented a fantastic opportunity to explore plant biodiversity. Photo by Bob Leckridge. Used under Creative Commons 2.0.

GW: The project was funded by the Government of Alberta and the investment firm Musea Ventures to raise the profile of the University of Alberta. Notably there was no requirement by the funders to sequence any particular species. I was able to ask the plant science community what the best possible use of these resources would be. The community was in full agreement that the money should be used to sample plant diversity.

Hopefully our work will change the thinking at the funding agencies regarding the value of sequencing biodiversity.

What techniques were utilized in this project to carry out the research?

GW: Complete genomes were too expensive to sequence. Many plants have unusually large genomes and de novo assembly of a polyploid genome remains difficult. To overcome this problem, we sequenced transcriptomes. However, this made our sample collection more difficult as the tissue had to be fresh. In addition, when we started the project, the software to assemble de novo transcriptomes did not work particularly well. I simply made a bet that these problems would be solved by the time we collected the samples and extracted the RNA. For the most part that’s what happened, although we did end up developing our own assembly software as well!

The 1KP initiative is an international consortium. How has the group evolved over time and what benefits have you seen from having this diverse set of skills?

GW: 1KP would not be where it is today without the participation of scientists around the world from many different backgrounds. For example, plant systematists who defined species of interest and provided the tissue samples worked alongside bioinformaticians who analyzed the data, and gene family experts who are now publishing fascinating stories about particular genes.

 DS: One of the great things about this project is how it has evolved over time as new researchers became involved. There is no restriction on who can take part, which species can be studied or which questions can be asked of the data. This makes the 1KP initiative unique compared to more traditionally funded projects.

GW: We continually encouraged others to get involved and mine our data for interesting information. We did a lot of this through word of mouth and ended up with some highly interesting, unexpected discoveries. For example, an optogenetics group at MIT and Harvard used our data to develop new tools for mammalian neurosciences. This really highlights the importance of not restricting the species we study to those of known economic importance.

According to ISI outputs from this research, two of the most highly cited papers from 1KP are here and here.

You aimed to investigate a highly diverse array of plants. How many plants of the major phylogenetic groups have now been sequenced, and are you still working on expanding the data set?

DS: A lot of thought went into the species selection. We aimed for proportional representation (by number of species) of the major plant groups. We also aimed to represent the morphological diversity of those groups.

GW: Altogether, we generated 1345 transcriptomes from 1174 plant species.

Has this project lead to any breakthroughs in our understanding of the phylogeny of plants?

DS: This will be the first broad look at what the nuclear genome has to tell us, and the first meaningful comparison of large nuclear and plastid data sets. However, due to rapid evolution plus extinction, many parts of the plant evolutionary tree remain extremely difficult to solve.

Hornworts are non-vascular plants that grow in damp, humid places. Photo by Jason Hollinger. Used under Creative Commons License 2.0.

Hornworts are non-vascular plants that grow in damp, humid places. Photo by Jason Hollinger. Used under Creative Commons License 2.0.

One significant breakthrough was the discovery of horizontal gene transfer from a hornwort to a group of ferns. This was unexpected and very interesting in terms of the ability of those ferns to be able to accommodate understory habitats.

GW: With regard to horizontal gene transfer, there are papers in the pipeline that will illustrate the discovery of even more of these events in other species. We have also studied gene duplications at the whole genome and gene family level. This is the most comprehensive survey ever undertaken, and people will be surprised at the scale of the discoveries. However, we will be releasing our findings shortly as part of a series and it would be unwise for us to give the story away here! Keep a look out for these!

A year at the Global Plant Council

Last April I joined the Global Plant Council as a New Media Fellow along with Sarah Jose from the University of Bristol. The GPC is a small organization with a big remit: to bring together stakeholders in the plant and crop sciences from around the world! As New Media Fellows, Sarah and I have have assisted in raising the online profile of the GPC through various social media platforms. We wrote about our experiences in growing this blog and the GPC Twitter and Facebook accounts in the The Global Plant Council Guide to Social Media, which details our successes and difficulties in creating a more established online presence.

 

Why do it?

My wheat growing in Norfolk field trials. I have spent every summer for the past 3 years out here analysing photosynthesis and other possible contributors to crop yield

My wheat growing in Norfolk field trials. I have spent every summer for the past 3 years out here analysing photosynthesis and other possible contributors to crop yield

I chose to apply for the fellowship during the third year of my PhD. Around this time I had started to consider that perhaps a job in research wasn’t for me. It was therefore important to gain experience outside of my daily life in the lab and field, explore possible careers outside of academia and of course to add vital lines to my CV. I still loved science, and found my work interesting, so knew I wanted to stay close to the scientific community. Furthermore, I had always enjoyed being active on Twitter, and following scientific blogs, so the GPC fellowship sounded like the perfect opportunity!

 

The experience

I think I can speak for both Sarah and myself when I say that this fellowship has been one of the best things I’ve done during my PhD. Managing this blog for a year has allowed me to speak to researchers working on diverse aspects of the plant sciences from around the world. My speed and writing efficiency have improved no end, and I can now write a decent 1000 word post in under an hour! I discovered the best places to find freely available photos, and best way to present a WordPress article. Assisting with Twitter gave me an excuse to spend hours reading interesting articles on the web – basically paid procrastination – and I got to use my creativity to come up with new ways of engaging our community.

Next career move, camera woman?

Filming interviews at the Stress Resilience Forum. Next career move, camera woman?

Of course going to Brazil for the Stress Resilience Symposium, GPC AGM and IPMB was a highlight of my year. I got to present to the international community both about my own PhD research and the work of the GPC, Sarah and I became expert camera women while making the Stress Resilience videos, and I saw the backstage workings of a conference giving out Plantae badges on the ASPB stand at IPMB. It didn’t hurt that I got to see Iguassu Falls, drink more than a few caipirinhas and spend a sneaky week in Rio de Janeiro!

Helping out on the ASPB stand

Helping out on the ASPB stand with Sarah

 

Thank you

Working with the GPC team has been fantastic. I learnt a lot about how scientific societies are run and the work they do by talking to the representatives from member societies at the AGM. The executive board have been highly supportive of our activities throughout. Last but not least, the lovely GPC ladies, Ruth, Lisa and Sarah have been an amazing team to work with – I cannot thank you enough!

I have now handed in my PhD, left the GPC, and moved on to a new career outside of academic research. I’m going into a job focused on public engagement and widening access to higher education, and have no doubt my GPC experiences have helped me get there. My advice if you’re unsure about where you want to end up after your PhD? Say “yes” to all new opportunities as you never know where they will take you.

Thank you the GPC! Hopefully I’ll be back one day!

 

Thank you! It's been amazing!

Thank you! It’s been amazing!

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.

 

 

 

 

 

 

 

 

 

 

 

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