Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Mexican farmers effectively cultivate phenotypic diversity in maize

30.04.2004


Erosion of genetic diversity of crop plants has for several decades been making it necessary to develop initiatives for protecting these plant resources. One strategy is in-situ conservation of crop plants. The model currently advanced involves maintaining the varieties to be conserved isolated in reserves, protected from entry of other varieties from elsewhere and cultivated according to ancestral farming practices. Researchers from the IRD and the CIMMYT of Mexico (1) used work previously conducted in Mexico on maize varieties, or landraces, to devise a different, dynamic, model judged more compatible with agricultural development and closer to the real conditions in which these plants diversified under the constant action of farmers (2). Insofar as local landraces are still grown as crops on sufficiently large areas of land, the introduction of others from outside, favouring a certain rate of gene flow, would in fact be a source of diversity rather than a factor of genetic erosion.



Mexico, the cradle of maize cultivation, is where this member of the Graminae family, a descendent of a local wild grass, teosinte, was domesticated and phenotypically diversified by human action, at least 6 000 years B.P. An in-situ conservation programme jointly run by CIMMYT, INIFAP (Mexican National Institute of Research in Forestry and Agriculture and Livestock Breeding) and the IRD, conducted in the central valleys of Oaxaca, enabled the research team to characterize the genetic structure of the different populations of local maize landraces and measured the impact of farming practices on this diversity. They focused on two types of diversity: phenotypic (concerning the morphological characters of the plants) and the genetic diversity (observed using genetic markers).

Study of the populations of maize landraces cultivated in six villages of this central region of Mexico has revealed that the morphological and agronomic characters in the field, such as ear size, kernel colour, or flowering period, vary depending on the farmer. At genome scale, genetic markers have shown strong homogeneity between the maize populations within the same village and, more surprisingly, between distant villages. This means that the local varieties possess a common genetic base. The diversity observed in characters of direct pertinence to farmers would consequently be the result of the latter’s personal decisions on seed selection, which they make before each crop cycle.


This region’s farmers currently grow the maize according to ancestral practices, established over hundreds of years. The fields are sown from one crop cycle to another with the seeds of the ears from the previous harvest. However, from time to time farmers decide to exchange seed batches with other neighbouring farmers, situated more or less geographically distant, in order to run experimental crops from these seeds. Each farmer thus judges the value of these seeds according to their characteristics. Selection criteria are still a highly individual choice and depend on a number of factors. For instance taste, colour, and cooking quality characteristics come into consideration as culinary criteria, leaf characteristics as forage quality criteria.

This investigation has brought the first genetic proof that these cultivation practices, conducted on a small scale (village and region), are a key element in the evolution of maize and its diversity. In-situ conservation of so-called "farm" varieties of crop plants, following the example of maize, could therefore be perceived in terms not of isolation, but of dynamic means of genetic material flow between the different populations of the same region in which the farmers play a predominant role. They thus appear to cultivate maize population diversity. These populations appear as open genetic systems, maintaining the centres of diversity of this major food cereal. The research conducted in this context on the inter-population gene flow should lead to better assessment of the risks from a spread of genetically modified –transgenic-corn varieties that might possibly be introduced into Mexico among traditional local landraces. Such work could therefore help provide some answers for the public debate which for many years has been running on this issue (3).


###
Marie Guillaume - DIC

(1) This investigation involved jointly research unit UR 141 "Diversité et génomes des plantes cultivées" and the CIMMYT (International Centre for Maize and Wheat Improvement) located in Mexico City.
(2) See FAS N°32, February 1997.
(3) A symposium on this topic is being held by the Commission for Environmental Cooperation of North America, in Oaxaca, Mexico, 11 March 2004. See www.cec.org

An article has also appeared: M. R. Bellon and J. Berthaud, 2004 – Transgenic maize and the evolution of landrace diversity in Mexico: The importance of farmers’ behavior, Plant Physiology, 1st March 2004, 134 (3).

FOR FURTHER INFORMATION

Contacter: Julien Berthaud – IRD UR 141 – " Diversité et génomes des plantes cultivées ", 911 avenue Agropolis, BP 64501, 34394 Montpellier cedex 5. Tel.:33-4-67-41-61-65. Email: Berthaud@ird.fr

Contacts IRD Communication: Marie Guillaume (editor), Tel.:33-1-48-03-76-07, Email: guillaum@paris.ird.fr ; Bénédicte Robert (press officer), Tel.: 33-1-48-03-75-19, Email:presse@paris.ird.fr

References :

G. Pressoir and J. Berthaud, 2004 – Patterns of population structure in maize landraces from the Central Valleys of Oaxaca in Mexico, Heredity, 92, 88 - 94 (01 February 2004)
G. Pressoir and J. Berthaud, 2004 – Population structure and strong divergent selection shape phenotypic diversification in Maize landraces, Heredity, 92, 95-101 (01 February 2004)
M. R. Bellon, J. Berthaud et al., 2003 - Participatory landrace selection for on farm conservation : an example from the Central Valleys of Oaxaca, Mexico, Genetic Resources and Crop Evolution, 50, 401-416

To obtain illustrations concerning this research
Contact Indigo Base, IRD picture library, Claire Lissalde or Danièle Cavanna, Tel.: 33-1-48-03-78-99, Email: indigo@paris.ird.fr

Bénédicte Robert | EurekAlert!
Further information:
http://www.ird.fr/fr/actualites/fiches/2004/fiche197.htm

More articles from Agricultural and Forestry Science:

nachricht Plasma-zapping process could yield trans fat-free soybean oil product
02.12.2016 | Purdue University

nachricht New findings about the deformed wing virus, a major factor in honey bee colony mortality
11.11.2016 | Veterinärmedizinische Universität Wien

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Simple processing technique could cut cost of organic PV and wearable electronics

06.12.2016 | Materials Sciences

3-D printed kidney phantoms aid nuclear medicine dosing calibration

06.12.2016 | Medical Engineering

Robot on demand: Mobile machining of aircraft components with high precision

06.12.2016 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>