Time filter

Source Type

Prasanna B.M.,International Maize and Wheat Improvement Center
Journal of Biosciences

Maize (Zea mays L.) is not only of worldwide importance as a food, feed and as a source of diverse industrially important products, but is also a model genetic organism with immense genetic diversity. Although it was first domesticated in Mexico, maize landraces are widely found across the continents. Several studies in Mexico and other countries highlighted the genetic variability in the maize germplasm. Applications of molecular markers, particularly in the last two decades, have led to new insights into the patterns of genetic diversity in maize globally, including landraces as well as wild relatives (especially teosintes) in Latin America, helping in tracking the migration routes of maize from the centers of origin, and understanding the fate of genetic diversity during maize domestication. The genome sequencing of B73 (a highly popular US Corn Belt inbred) and Palomero (a popcorn landrace in Mexico) in the recent years are important landmarks in maize research, with significant implications to our understanding of the maize genome organization and evolution. Next-generation sequencing and high-throughput genotyping platforms promise to further revolutionize our understanding of genetic diversity and for designing strategies to utilize the genomic information for maize improvement. However, the major limiting factor to exploit the genetic diversity in crops like maize is no longer genotyping, but high-throughput and precision phenotyping. There is an urgent need to establish a global phenotyping network for comprehensive and efficient characterization of maize germplasm for an array of target traits, particularly for biotic and abiotic stress tolerance and nutritional quality. 'Seeds of Discovery' (SeeD), a novel initiative by CIMMYT with financial support from the Mexican Government for generating international public goods, has initiated intensive exploration of phenotypic and molecular diversity of maize germplasm conserved in the CIMMYT Gene Bank; this is expected to aid in effective identification and use of novel alleles and haplotypes for maize improvement. Multi-institutional efforts are required at the global level to systematically explore the maize germplasm to diversify the genetic base of elite breeding materials, create novel varieties and counter the effects of global climate changes. © Indian Academy of Sciences. Source

Bellon M.R.,Diversity for Livelihoods Programme | Hodson D.,Food and Agriculture Organization of the United Nations | Hellin J.,International Maize and Wheat Improvement Center
Proceedings of the National Academy of Sciences of the United States of America

Climate change is predicted to have major impacts on small-scale farmers in Mexico whose livelihoods depend on rain-fed maize. We examined the capacity of traditional maize seed systems to provide these farmers with appropriate genetic material under predicted agro-ecological conditions associated with climate change. We studied the structure and spatial scope of seed systems of 20 communities in four transects across an altitudinal gradient from 10-2,980 m above sea level in five states of eastern Mexico. Results indicate that 90% of all of the seed lots are obtained within 10 km of a community and 87% within an altitudinal range of ±50 m but with variation across four agro-climate environments: wet lowland, dry lowland, wet upper midlatitude, and highlands. Climate models suggest a drying and warming trend for the entire study area during the main maize season, leading to substantial shifts in the spatial distribution patterns of agro-climate environments. For all communities except those in the highlands, predicted future maize environments already are represented within the 10-km radial zones, indicating that in the future farmers will have easy access to adapted planting material. Farmers in the highlands are the most vulnerable and probably will need to acquire seed fromoutside their traditional geographical ranges. This change in seed sources probably will entail important information costs and the development of new seed and associated social networks, including improved linkages between traditional and formal seed systems and more effective and efficient seed-supply chains. The study has implications for analogous areas elsewhere in Mexico and around the world. Source

Erenstein O.,International Maize and Wheat Improvement Center
Land Use Policy

Intensive irrigated rice-wheat production systems have converted the north-west Indo-Gangetic Plains into South Asia's cereal basket. Their strategic importance is undermined by a slowdown in productivity growth linked to the degradation of soil and water resources. Findings from farm surveys are used to examine contrasts and similarities between rice and wheat farms, cultivation practices, productivity, and profitability in the rice-wheat belt of India's Haryana State and Pakistan's Punjab province. In Haryana average wheat and paddy yields are markedly higher, but the yield advantage is offset by higher total production costs, resulting in lower private returns. The diverging institutional environment including varying levels of intervention in produce and input markets contributed to the evolution of the Pakistani production model as relatively 'medium input-medium output' and the Indian production model as 'high input-high output'. The study reiterates the need to reinvigorate productivity growth and to reduce production costs in these intensive cereal production systems while conserving natural resources such as water and limiting negative environmental impacts. The study however also raises questions about the future of current rice-wheat systems. © 2009 Elsevier Ltd. All rights reserved. Source

Hellin J.,International Maize and Wheat Improvement Center
Journal of Agricultural Education and Extension

Purpose: New approaches to extension service delivery are needed that stimulate increased agricultural production, contribute to collective action and which also foster the emergence of agricultural innovation systems. Research in Peru and Mexico explores some of these new approaches. Design/methodology/approach: In both countries, a qualitative value chain mapping methodology was used to explore the challenges of providing extension provision to resource-poor farmers in ways that stimulate collective action and agricultural innovation systems. Findings: In Peru, collective action and the development of an agriculture innovation system required the network broker activities of initially a non-governmental organization (NGO) and then increasingly trusted local farmers known as Kamayoq. In Mexico, collective action took place in the context of a linear transfer-of-technology approach focused on access to improved maize seed and there was no evidence of the emergence of innovation networks. Practical implications: Different extension modalities can foster collective action but this in itself is not enough to encourage innovation. Extension needs to focus on combining collective action with networking amongst sets of heterogeneous value chain actors. Originality/value: The Peruvian and Mexican case studies demonstrate that the debate about the modalities of pluralistic and diversified extension systems has obscured the reality that the development community still has some way to go to achieve comprehensively the paradigm shift from a linear transfer-of-technology approach to one that supports the emergence of agricultural innovation systems. © 2012 Wageningen University. Source

Semagn K.,International Maize and Wheat Improvement Center
Methods in Molecular Biology

Taxonomists must be familiar with a number of issues in collecting and transporting samples using freezing methods (liquid nitrogen and dry ice), desiccants (silica gel and blotter paper), and preservatives (CTAB, ethanol, and isopropanol), with each method having its own merits and limitations. For most molecular studies, a reasonably good quality and quantity of DNA is required, which can only be obtained using standard DNA extraction protocols. There are many DNA extraction protocols that vary from simple and quick ones that yield low-quality DNA but good enough for routine analyses to the laborious and time-consuming standard methods that usually produce high quality and quantities of DNA. The protocol to be chosen will depend on the quality and quantity of DNA needed, the nature of samples, and the presence of natural substances that may interfere with the extraction and subsequent analysis. The protocol described in this chapter has been tested for extracting DNA from eight species and provided very good quality and quantity of DNA for different applications, including those genotyping methods that use restriction enzymes. © 2014 Springer Science+Business Media New York. Source

Discover hidden collaborations