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"Crops Genetic engineering Africa."
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Africa's gene revolution : genetically modified crops and the future of African agriculture
\"As development donors invest hundreds of millions of dollars into improved crops designed to alleviate poverty and hunger, Africa has emerged as the final frontier in the global debate over agricultural biotechnology. The first data-driven assessment of the ecological, social, and political factors that shape our understanding of genetic modification, Africa's Gene Revolution surveys twenty years of efforts to use genomics-based breeding to enhance yields and livelihoods for African farmers. Matthew Schnurr considers the full range of biotechnologies currently in commercial use and those in development - including hybrids, marker-assisted breeding, tissue culture, and genetic engineering.. Drawing on interviews with biotechnology experts alongside research conducted with more than two hundred farmers across eastern, western, and southern Africa, Schnurr reveals a profound incongruity between the optimistic rhetoric that accompanies genetic modified technology and the realities of the smallholder farmers who are its intended beneficiaries. Through the lens of political ecology, this book demonstrates that the current emphasis on improved seeds discounts the geographic, social, ecological, and economic contexts in which the producers of these crops operate. Bringing the voices of farmers to the foreground of this polarizing debate, Africa's Gene Revolution contends that meaningful change will come from a reconfiguration not only of the plant's genome, but of the entire agricultural system.\"-- Provided by publisher.
Book
Starved for science
Listen to a short interview with Robert PaarlbergHost: Chris Gondek | Producer: Heron & Crane
Heading upcountry in Africa to visit small farms is absolutely exhilarating given the dramatic beauty of big skies, red soil, and arid vistas, but eventually the two-lane tarmac narrows to rutted dirt, and the journey must continue on foot. The farmers you eventually meet are mostly women, hardworking but visibly poor. They have no improved seeds, no chemical fertilizers, no irrigation, and with their meager crops they earn less than a dollar a day. Many are malnourished.
Nearly two-thirds of Africans are employed in agriculture, yet on a per-capita basis they produce roughly 20 percent less than they did in 1970. Although modern agricultural science was the key to reducing rural poverty in Asia, modern farm science—including biotechnology—has recently been kept out of Africa.
In Starved for Science Robert Paarlberg explains why poor African farmers are denied access to productive technologies, particularly genetically engineered seeds with improved resistance to insects and drought. He traces this obstacle to the current opposition to farm science in prosperous countries. Having embraced agricultural science to become well-fed themselves, those in wealthy countries are now instructing Africans—on the most dubious grounds—not to do the same.
In a book sure to generate intense debate, Paarlberg details how this cultural turn against agricultural science among affluent societies is now being exported, inappropriately, to Africa. Those who are opposed to the use of agricultural technologies are telling African farmers that, in effect, it would be just as well for them to remain poor.
eBook
Developing a flexible, high‐efficiency Agrobacterium‐mediated sorghum transformation system with broad application
Summary Sorghum is the fifth most widely planted cereal crop in the world and is commonly cultivated in arid and semi‐arid regions such as Africa. Despite its importance as a food source, sorghum genetic improvement through transgenic approaches has been limited because of an inefficient transformation system. Here, we report a ternary vector (also known as cohabitating vector) system using a recently described pVIR accessory plasmid that facilitates efficient Agrobacterium‐mediated transformation of sorghum. We report regeneration frequencies ranging from 6% to 29% in Tx430 using different selectable markers and single copy, backbone free ‘quality events’ ranging from 45% to 66% of the total events produced. Furthermore, we successfully applied this ternary system to develop transformation protocols for popular but recalcitrant African varieties including Macia, Malisor 84‐7 and Tegemeo. In addition, we report the use of this technology to develop the first stable CRISPR/Cas9‐mediated gene knockouts in Tx430.
Journal Article
Rooting for cassava
As a consequence of an increase in world population, food demand is expected to grow by up to 110% in the next 30–35 yr. The population of sub-Saharan Africa is projected to increase by > 120%. In this region, cassava (Manihot esculenta) is the second most important source of calories and contributes c. 30% of the daily calorie requirements per person. Despite its importance, the average yield of cassava in Africa has not increased significantly since 1961. An evaluation of modern cultivars of cassava showed that the interception efficiency (ɛi) of photosynthetically active radiation (PAR) and the efficiency of conversion of that intercepted PAR (ɛc) are major opportunities for genetic improvement of the yield potential. This review examines what is known of the physiological processes underlying productivity in cassava and seeks to provide some strategies and directions toward yield improvement through genetic alterations to physiology to increase ɛi and ɛc. Possible physiological limitations, as well as environmental constraints, are discussed.
Journal Article
Photosynthesis across African cassava germplasm is limited by Rubisco and mesophyll conductance at steady state, but by stomatal conductance in fluctuating light
• Sub-Saharan Africa is projected to see a 55% increase in food demand by 2035, where cassava (Manihot esculenta) is the most widely planted crop and a major calorie source. Yet, cassava yield in this region has not increased significantly for 13 yr. Improvement of genetic yield potential, the basis of the first Green Revolution, could be realized by improving photosynthetic efficiency. First, the factors limiting photosynthesis and their genetic variability within extant germplasm must be understood.
• Biochemical and diffusive limitations to leaf photosynthetic CO₂ uptake under steady state and fluctuating light in 13 farm-preferred and high-yielding African cultivars were analyzed. A cassava leaf metabolic model was developed to quantify the value of overcoming limitations to leaf photosynthesis.
• At steady state, in vivo Rubisco activity and mesophyll conductance accounted for 84% of the limitation. Under nonsteady-state conditions of shade to sun transition, stomatal conductance was the major limitation, resulting in an estimated 13% and 5% losses in CO₂ uptake and water use efficiency, across a diurnal period. Triose phosphate utilization, although sufficient to support observed rates, would limit improvement in leaf photosynthesis to 33%, unless improved itself.
• The variation of carbon assimilation among cultivars was three times greater under non-steady state compared to steady state, pinpointing important overlooked breeding targets for improved photosynthetic efficiency in cassava.
Journal Article
Maize Lethal Necrosis disease: review of molecular and genetic resistance mechanisms, socio-economic impacts, and mitigation strategies in sub-Saharan Africa
Background
Maize lethal necrosis (MLN) disease is a significant constraint for maize producers in sub-Saharan Africa (SSA). The disease decimates the maize crop, in some cases, causing total crop failure with far-reaching impacts on regional food security.
Results
In this review, we analyze the impacts of MLN in Africa, finding that resource-poor farmers and consumers are the most vulnerable populations. We examine the molecular mechanism of MLN virus transmission, role of vectors and host plant resistance identifying a range of potential opportunities for genetic and phytosanitary interventions to control MLN. We discuss the likely exacerbating effects of climate change on the MLN menace and describe a sobering example of negative genetic association between tolerance to heat/drought and susceptibility to viral infection. We also review role of microRNAs in host plant response to MLN causing viruses as well as heat/drought stress that can be carefully engineered to develop resistant varieties using novel molecular techniques.
Conclusions
With the dual drivers of increased crop loss due to MLN and increased demand of maize for food, the development and deployment of simple and safe technologies, like resistant cultivars developed through accelerated breeding or emerging gene editing technologies, will have substantial positive impact on livelihoods in the region. We have summarized the available genetic resources and identified a few large-effect QTLs that can be further exploited to accelerate conversion of existing farmer-preferred varieties into resistant cultivars.
Journal Article
Synthetic biology approaches to engineering the nitrogen symbiosis in cereals
Nitrogen is abundant in the earth’s atmosphere but, unlike carbon, cannot be directly assimilated by plants. The limitation this places on plant productivity has been circumvented in contemporary agriculture through the production and application of chemical fertilizers. The chemical reduction of nitrogen for this purpose consumes large amounts of energy and the reactive nitrogen released into the environment as a result of fertilizer application leads to greenhouse gas emissions, as well as widespread eutrophication of aquatic ecosystems. The environmental impacts are intensified by injudicious use of fertilizers in many parts of the world. Simultaneously, limitations in the production and supply of chemical fertilizers in other regions are leading to low agricultural productivity and malnutrition. Nitrogen can be directly fixed from the atmosphere by some bacteria and Archaea, which possess the enzyme nitrogenase. Some plant species, most notably legumes, have evolved close symbiotic associations with nitrogen-fixing bacteria. Engineering cereal crops with the capability to fix their own nitrogen could one day address the problems created by the over- and under-use of nitrogen fertilizers in agriculture. This could be achieved either by expression of a functional nitrogenase enzyme in the cells of the cereal crop or through transferring the capability to form a symbiotic association with nitrogen-fixing bacteria. While potentially transformative, these biotechnological approaches are challenging; however, with recent advances in synthetic biology they are viable long-term goals. This review discusses the possibility of these biotechnological solutions to the nitrogen problem, focusing on engineering the nitrogen symbiosis in cereals.
Journal Article
Pyricularia oryzae: Lab star and field scourge
Pyricularia oryzae (syn. Magnaporthe oryzae), is a filamentous ascomycete that causes a major disease called blast on cereal crops, as well as on a wide variety of wild and cultivated grasses. Blast diseases have a tremendous impact worldwide particularly on rice and on wheat, where the disease emerged in South America in the 1980s, before spreading to Asia and Africa. Its economic importance, coupled with its amenability to molecular and genetic manipulation, have inspired extensive research efforts aiming at understanding its biology and evolution. In the past 40 years, this plant‐pathogenic fungus has emerged as a major model in molecular plant–microbe interactions. In this review, we focus on the clarification of the taxonomy and genetic structure of the species and its host range determinants. We also discuss recent molecular studies deciphering its lifecycle. Taxonomy Kingdom: Fungi, phylum: Ascomycota, sub‐phylum: Pezizomycotina, class: Sordariomycetes, order: Magnaporthales, family: Pyriculariaceae, genus: Pyricularia. Host range P. oryzae has the ability to infect a wide range of Poaceae. It is structured into different host‐specialized lineages that are each associated with a few host plant genera. The fungus is best known to cause tremendous damage to rice crops, but it can also attack other economically important crops such as wheat, maize, barley, and finger millet. Disease symptoms P. oryzae can cause necrotic lesions or bleaching on all aerial parts of its host plants, including leaf blades, sheaths, and inflorescences (panicles, spikes, and seeds). Characteristic symptoms on leaves are diamond‐shaped silver lesions that often have a brown margin and whose appearance is influenced by numerous factors such as the plant genotype and environmental conditions. USEFUL WEBSITES Resources URL Genomic data repositories http://genome.jouy.inra.fr/gemo/ Genomic data repositories http://openriceblast.org/ Genomic data repositories http://openwheatblast.net/ Genome browser for fungi (including P. oryzae) http://fungi.ensembl.org/index.html Comparative genomics database https://mycocosm.jgi.doe.gov/mycocosm/home T‐DNA mutant database http://atmt.snu.kr/ T‐DNA mutant database http://www.phi‐base.org/ SNP and expression data https://fungidb.org/fungidb/app/ The fungal pathogen Pyricularia oryzae (syn. Magnaporthe oryzae) is the causal agent of blast disease on cereals and grasses and a model organism in plant–pathogen interaction research.
Journal Article
Managing Fall Armyworm in Africa: Can Bt Maize Sustainably Improve Control?
The recent invasion of Africa by fall armyworm, Spodoptera frugiperda, a lepidopteran pest of maize and other crops, has heightened concerns about food security for millions of smallholder farmers. Maize genetically engineered to produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) is a potentially useful tool for controlling fall armyworm and other lepidopteran pests of maize in Africa. In the Americas, however, fall armyworm rapidly evolved practical resistance to maize producing one Bt toxin (Cry1Ab or Cry1Fa). Also, aside from South Africa, Bt maize has not been approved for cultivation in Africa, where stakeholders in each nation will make decisions about its deployment. In the context of Africa, we address maize production and use; fall armyworm distribution, host range, and impact; fall armyworm control tactics other than Bt maize; and strategies to make Bt maize more sustainable and accessible to smallholders. We recommend mandated refuges of non-Bt maize or other non-Bt host plants of at least 50% of total maize hectares for single-toxin Bt maize and 20% for Bt maize producing two or more distinct toxins that are each highly effective against fall armyworm. The smallholder practices of planting more than one maize cultivar and intercropping maize with other fall armyworm host plants could facilitate compliance. We also propose creating and providing smallholder farmers access to Bt maize that produces four distinct Bt toxins encoded by linked genes in a single transgene cassette. Using this novel Bt maize as one component of integrated pest management could sustainably improve control of lepidopteran pests including fall armyworm.
Journal Article