The impact of GM seed admixture on the non-GM harvest product in maize (Zea mays L.)

Abstract

Recently, the introduction of GM maize in agricultural production in the EU and elsewhere has raised the issue of adventitious presence of GM seeds in conventional seed lots. Adventitious presence may occur in all arable farming, and at any step in the production of seeds or grain, or in processing of harvested product in the food/feed chain. As of today, there are no official thresholds governing the adventitious presence of GM seeds in conventional seed lots in Europe. However, it is assumed that GM admixture in seed lots could have a considerable influence on the level of adventitious presence in the non-GM harvested product. The experiments highlighted in this paper aim at the consequences of adventitious presence of GM maize seeds in conventional seed lots. It is shown for varieties belonging to the same maturity group that the final GM rate (% seeds) in the harvest product is nearly same as the initial seed admixture (% seeds). This corresponds to Hardy-Weinberg expectations. The variation depends mainly on the flowering coincidence, the site and climatic conditions. In cases where the admixed seeds are of different maturity group, the level of cross-pollination in the harvest product is reduced. Furthermore a comparison between the visual GM seed detection and real-time PCR detection was done. It is evident that the result of the real-time PCR detection method has a more variable uncertainty associated with its results than the visual seed testing method. The accuracy of prediction from % GM seed to % GM DNA depends on the reference material used for calibration curves.

Application of fault tree analysis: Failure mode and effect analysis to evaluate critical factors influencing non‐GM segregation in the US grain and feed supply chain

“…Non‐GM seeds may unintentionally incur GM impurity if produced and handled in an environment that also handles GM seeds. Commercial seed companies implement strict protocols to maintain minimum impurity in certified non‐GM seeds but cannot guarantee absolute purity, mainly for cross‐pollinating crops like corn due to pollen flow in seed production fields (Njontie et al, 2011). The impurity may also occur during seed harvesting, conditioning, and handling as it is difficult to assure that all handling equipment are completely free of GM material (Bradford, 2006).…”

Adventitious presence of GMOs in maize in the view of coexistence

“…If the varieties are of different maturity, the level of APGM in the harvest is reduced (Njontie et al, 2011). If assuming the worst case presence of seed impurities (0.5% GM in non-GM seeds), the APGM from the field (cross-fertilization at the field) and post-field processes (mixing at harvest and inpost-harvest processes) should not exceed more than 0.4% (Sanvido et al, 2008).…”

Sampling Strategies for Evaluating the Rate of Adventitious Transgene Presence in Non‐Genetically Modified Crop Fields

“…Pollen emitted by GM maize may be dispersed over nearby non‐GM maize fields, resulting in the fertilization of non‐GM maize plants . A fraction of the grains produced by the non‐GM maize crops may thus contain the transgene from the GM maize crop . If this fraction is large enough, then the commercial product derived from non‐GM maize may lose its GM‐free status and any related price premium.…”

“…The coexistence of genetically modified (GM) and conventional crops in the same area has become an important issue since the introduction of GM crops a few decades ago, due to gene flow be-tween fields during pollination. (1)(2)(3)(4) It remains highly controversial because of the risk of transgenes passing from outcrossing GM crops to non-GM crops, which may be costly to non-GM crop growers, as reported for GM maize. (5) Pollen emitted by GM maize may be dispersed over nearby non-GM maize fields, resulting in the fertilization of non-GM maize plants.…”