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!
Joining forces for immune research
13.08.2018 | Max-Delbrück-Centrum für Molekulare Medizin in der Helmholtz-Gemeinschaft
The “TRiC” to folding actin
10.08.2018 | Max-Planck-Institut für Biochemie
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur
What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...
The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.
Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...
If certain signaling cascades are misregulated, diseases like cancer, obesity and diabetes may occur. A mechanism recently discovered by scientists at the Leibniz- Forschungsinstitut für Molekulare Pharmakologie (FMP) in Berlin and at the University of Geneva has a crucial influence on such signaling cascades and may be an important key for the future development of therapies against these diseases. The results of the study have just been published in the prestigious scientific journal 'Molecular Cell'.
Cell growth and cell differentiation as well as the release and efficacy of hormones such as insulin depend on the presence of lipids. Lipids are small...
08.08.2018 | Event News
27.07.2018 | Event News
25.07.2018 | Event News
13.08.2018 | Physics and Astronomy
13.08.2018 | Life Sciences
13.08.2018 | Information Technology