Gene flow scenarios with transgenic maize in Mexico

Abstract

Maize diversity is widespread in Mexico and it has been stewarded by campesinos in small communities until the present. With the arrival of transgenic maize, the objective of this study is to analyze possible scenarios that could result if genetically modified maize were not regulated and openly available in Mexico. By applying a simple logistic model based on the conditions of maize production in Mexico, the dispersion of transgenic maize in different situations within fields of farmers is described. In traditional open systems of freely exchanged seed within communities it is concluded that the most likely outcome of GM maize release is the incorporation of transgenes in the genome of Mexican germplasm and possibly in that of teosinte.

New Genes in Traditional Seed Systems: Diffusion, Detectability and Persistence of Transgenes in a Maize Metapopulation

“…By combining quantitative observations on traditional maize seed systems with a spatially explicit model, we are able to predict how deviations from observed practice may change the outcome of the introduction of a novel gene in terms of its diffusion, detectability and persistence. Our approach is a significant improvement over previous modeling studies that did not consider population genetics or seed management practices [31] [10].…”

Challenges for transgene detection in landraces and wild relatives: learning from 15 years of debate over GM maize in Mexico

“…through empirical or geostatistical methods) can help to calculate the detection power of different sampling approaches. However, although a farmer's plot or a determined region/area may be considered a limit to determine a cultivation area of interest, it is important to remember that these almost never represent an actual barrier to transgene flow (Serratos-Hernández et al 2004). Figure 3 shows the average size of a farmers plot in the Oaxaca region where most of the transgene detection studies were performed.…”

Risks of Pollen-Mediated Gene Flow From Genetically Modified Maize During Co-Cultivation With Usual Maize Varieties

“…В Мексике создано и хранится более 9 тыс. сортообразцов (54), популяции подвидов кукурузы (Zea mexicana, Z. parviglumis) и виды растения теосинте, которые участвовали в селекции современной кукурузы в Мексике (55).…”

“…Следует отметить, что в Мексике в отличие от многих других стран имеется дополнительный фактор повышенного риска неконтролируемого распространения ГМ-кукурузы: при выращивании этой культуры мелкие фермеры традиционно обмениваются зерном для посева, а также высевают смешанные популяции кукурузы (так называемая креолизация) (58). Моделирование распространения в Мексике ГМкукурузы в описанных условиях показало, что при засеве ею 5 га в каждом из 13 регионов через 10 лет ГМ-растения будут присутствовать в 87,85 % всех посевов (55).…”