A CRISPR future?
One of the most talked-about technologies in scientific circles at present is CRISPR-Cas9, a game-changing gene-editing technique that is set to have wide ramifications for medical advancement as well as agriculture.
CRISPR – or Clustered Regularly Interspaced Short Palindromic Repeats, to give it its technical title – are essentially molecular scissors that allow scientists to accurately cut DNA, therefore allowing the genome of a plant, animal or human to be edited. It varies from traditional genetic modification in that nothing is added to the DNA, but instead elements are simply removed.
As well as having huge potential in human disease prevention, CRISPR-Cas9 has a wide range of potential applications in agriculture, from avian flu-resistant poultry to drought-resistant crops. Critics argue that messing in the DNA of living organisms to create, for example, chickens that develop only female offspring for egg laying, goes too far, but supporters insist it is a much less invasive process than adding or combining genetic material and it could have a huge effect on securing the world’s food supply and reducing disease.
Among the range of horticultural applications to have already come out of Cas9 are non-browning mushrooms, whereby the gene-editing process reduces production of a specific enzyme that causes mushrooms to turn brown. The end product is a mushroom with longer shelf life that resists blemishes caused by handling or mechanical harvesting, but without DNA from a foreign organism.
“This technology holds promise for precision breeding of crops with many desirable traits, such as low levels of food allergens or toxins, disease resistance, drought tolerance, and efficient nitrogen and phosphorous utilisation,” said Yinong Yang, professor of plant pathology at Penn State’s College of Agricultural Sciences, who developed the non-browning mushroom. “These agronomic traits not only help reduce pesticide, fertiliser and water usage, but also improve food quality and safety.”
CRISPR is one of the most significant breakthroughs in recent years, and while a regulatory framework is yet to be agreed and there are concerns that gene-edited plants or animals will be untraceable as having been modified, it seems certain the technology has a major role to play in the future of agricultural science.
Hawaii high five
Plant scientists at the University of Nottingham have identified a ‘Hawaiian Skirt’ gene that plays a critical role in plant growth and development – a discovery they say will help improve crop yields and address the growing problem of food security.
The research, published in December in open access journal PLOS One, was led by Dr Zinnia Gonzalez-Carranza from the School of Biosciences and has pinpointed the role of a gene which has been dubbed ‘Hawaiian Skirt’ due to the fusing effect it has on the floral sepals.
Plant growth is driven by an increase in two factors: the number of cells, and their size, and this research shows that the Hawaiian Skirt gene regulates cell proliferation, floral development and floral organ number.
The trial used a model plant system, in which seeds were irradiated to create mutations that show abnormalities in flower development. “In our mutations we found the Hawaiian Skirt gene belongs to a group of regulatory proteins that function inside a cell in a very similar way to a recycling factory in a city,” explains Gonzalez-Carranza. “Once a protein has finished its function in the cell, in order to survive the protein must be degraded and recycled. Hawaiian Skirt is in charge of this process, which if it fails could cause unwanted affects altering the growth and development of the plant.”
Gonzalez-Carranza says that understanding the mechanisms of Hawaiian Skirt allows scientists to come up with novel alternatives to generate stronger and more productive crops by identifying key genes that regulate plant growth and response to stress. “Silencing or increasing the proteins they produce can have, for example, two important effects – the first is increasing the size of grains, which increases the yield of staple crops; the second is increasing the size and structure of root systems, which improves the resilience of plants to stressful conditions such as drought. All of which makes our research highly relevant to global food security.”
Home pregnancy test scienceboosts brassicas
The science behind the home pregnancy test could help detect the presence of diseases that can devastate fields of vegetable crops.
Trials are currently underway to help protect crops of brassicas and onions, with diseases including ring spot, light leaf spot and downy mildew being monitored. The test, known as a lateral flow device (LFD), picks up the presence of infective spores carried in the air around crops in the field. Used alongside weather data, test results could indicate how likely a disease is to develop, allowing growers to decide if crop protection methods are needed or not.
AHDB senior scientist Cathryn Lambourne says: “When it’s fully developed this simple low-cost tool, allowing growers to test whether there is a risk of diseases developing on their crops, will help prevent significant financial losses and reduce the need to use conventional methods to protect their crops.
“Over the last four years we’ve been developing the lateral flow device test, demonstrating how simple and effective it is, to give growers the confidence to rely on the results and make appropriate decisions for their business.”
The LFD tests are also being developed to detect for other plant diseases. AHDB is funding the University of Worcester to develop lab tests and LFDs to test for oomycete pathogens, which cause diseases like blight and sudden oak death. Primary testing is focused on root, stem and crown rots caused by Pythium and the Phytophthora species, commonly known as ‘the plant destroyer’, which can affect a range of crops.
Light at the endof the tunnel
Scientists from Wageningen University & Research have found natural genetic variation for photosynthesis in plants and are unravelling it to the DNA level. As a result it should be possible to breed crops that use photosynthesis more effectively in the future, increasing their yield and enabling them to capture more CO2 from the air in the soil.
Led by Mark Aarts and Jeremy Harbinson, a team of scientists has shown that thale cress – a common model plant – has various genes involved in the adaptation to changes in the amount of light to which plants are exposed. Their study is published in the journal Nature Communications.
One gene has already been studied in detail. Known as the Yellow Seedling 1 gene, it is involved in the adaptation of chloroplasts to light changes. Due to a variation in this gene, some thale cress plants can handle an increase of light (the difference between a cloudy and a sunny day, for example) better than others. It is the first time that this variation has been found in thale cress, but as the genes for photosynthesis occur in nearly all plant species, the scientists expect that a similar variation can be found in many other crops too.
The discovery shows it is possible to improve photosynthesis based on natural genetic variation, something which was doubted until now. In the long term, breeding on improved photosynthesis could make crops produce more yield with the same amount of soil, water and nutrients. This brings the concept of ‘more’ (yield) ‘with less’ (soil, water and nutrients) one step closer.
Overcoming drought
New research could help crops beat climate change by identifying which plants are most tolerant to drought.
In the first study to predict whether different populations of the same plant species can adapt to climate change, scientists from the Max Planck Institute for Developmental Biology found that central European ones die first.
The researchers focused on mustard cress, which grows across Europe, Asia and northwest Africa. Scandinavian plants were found to be able to cope with extreme drought as well as those from Mediterranean countries, according to research to be published in Nature Ecology and Evolution. This could be because water in the Scandinavian soil is frozen for many months, making it inaccessible to plants and effectively creating drought conditions.
The researchers planted mustard cress seeds collected from over 200 locations as diverse as North Africa, Spain, central Europe and northern Sweden. After they had germinated under optimal conditions, the plants were challenged with severe drought, and their ability to survive this stress was recorded. Using large-scale genome sequencing information, specific genetic variants could be linked to the plants’ ability to survive longer. Combined with climate predictions from the Intergovernmental Panel on Climate Change, the team were then able to generate maps showing the location of genetic variants key to the species’ future survival.
With extreme drought events predicted to become increasingly widespread, the findings reported by the Max Planck Institute could help to rescue plant and animal species with pressing conservation needs. If populations with genetic variants that support drought adaptation can be found, they could be relocated to areas where such adaptations are most needed. Such introduced individuals would then greatly improve the local gene pool.
The same approach could be used to reduce a mismatch between crop varieties and their environment, helping to improve the performance of crops.
