Now, scientists at the University of Cape Town, South Africa, along with colleagues at the South African seed company, PANNAR Pty Ltd, have developed a resistant variety of maize that they hope will help alleviate food shortages as well as promote the reputation of genetically engineered (GE) foods in Africa.
Dr. Dionne Shepherd of the University of Cape Town will be presenting the results of her recent work and that of coauthors B. Owor, R. Edema, A. Varsani, D.P. Martin, J.A. Thomson and E.P. Rybicki, at the annual meeting of the American Society of Plant Biologists in Chicago (July 8, 11:20 AM) in a major symposium on Plant Biology in Sub-Saharan Africa organized by Debby Delmer of UC Davis.
Maize, which originated in Mexico, was carried to Africa in the 1500s and eventually displaced native food crops such as sorghum and millet. Maize streak virus, an endemic pathogen of native African grasses, was then carried to maize plants by viruliferous leafhoppers. African scientists have been working for more than a quarter century on developing resistant varieties of maize by selecting and crossing varieties with various degrees of resistance to the virus.
However, resistance requires multiple genes located on different chromosomes, so the process is not straightforward. The group at the University of Cape Town took the opposite approach. They mutated a viral gene that encodes a protein that the virus needs to replicate itself and inserted it into maize plants. When the virus infects one of these transgenic maize plants, the mutated protein, which is expressed at a high level, prevents the virus from replicating and killing the plant. The transgenic maize variety has proven consistently resistant to MSV and the trait can be reliably passed on to the next generation and in crosses to other varieties. Field trials are scheduled to begin soon, not only to test the effectiveness of the technology in the field but also to ensure that the GE maize variety has no unintended effects on beneficial organisms that may feed on it. The resistant maize will also be tested to ensure that the viral protein is digestible and non-allergenic. The MSV-resistant maize is the first GE crop developed and tested solely by Africans.
This group of scientists also surveyed 389 Ugandan MSV isolates to assess the diversity and genetic characteristics of this destructive pathogen. They found that the most prevalent strain of this virus is a product of recombination of different viral genotypes, thus identifying an important source of new pathogenic variants and illustrating the constantly changing evolutionary battle between plants and pathogens. MSV was first sequenced in 1984 and found to contain a genome of only 2700 DNA bases in a circle of single-stranded DNA. When it infects susceptible plants, they produce deformed cobs and are often severely dwarfed. As the name of the virus suggests, the leaves are marked with parallel, yellow-white streaks.
The timing of infection, the maize genotype, and prevailing climatic conditions can all influence the extent of damage wreaked by this viral pathogen. Young plants cannot survive the infection but older plants are better able to contain the infection, resulting in smaller losses of grain. However, drought can have a devastating effect on maize fields over a wide geographical area. Under warm and wet conditions, a long-bodied morph of the leafhopper C. mbila emerges, but this form only travels short distances of 10 meters or less, thus limiting its damage to crops. Under drought conditions, a stronger, short-bodied morph that can fly great distances spreads the disease over large areas, thus exacerbating the effects of the drought itself.
Disease caused by similar geminiviruses, Wheat dwarf virus (WDV) and various sugarcane streak viruses, also affect other crops, including barley, wheat, oats, sugarcane, and millet. Thus, the technology developed for MSV could potentially be adapted to develop resistance in these other crops. Virologist Edward Rybicki and microbiologist Jennifer Thomson are hopeful that this year’s field trials will demonstrate not only the effectiveness of this technology in producing resistance to a destructive pathogen but also the safety of GE foods. Part of the objective is to provide seed that will be sold at a minimal profit to subsistence farmers, thus removing the objection that GE technology is principally profit-driven.
Brian Hyps | EurekAlert!
How brains surrender to sleep
23.06.2017 | IMP - Forschungsinstitut für Molekulare Pathologie GmbH
A new technique isolates neuronal activity during memory consolidation
22.06.2017 | Spanish National Research Council (CSIC)
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
23.06.2017 | Physics and Astronomy
23.06.2017 | Physics and Astronomy
23.06.2017 | Information Technology