Pollen-mediated gene flow in flax (Linum usitatissimum L.): can genetically engineered and organic flax coexist?

Abstract

Coexistence allows growers and consumers the choice of producing or purchasing conventional or organic crops with known standards for adventitious presence of genetically engineered (GE) seed. Flax (Linum usitatissimum L.) is multipurpose oilseed crop in which product diversity and utility could be enhanced for industrial, nutraceutical and pharmaceutical markets through genetic engineering. If GE flax were released commercially, pollen-mediated gene flow will determine in part whether GE flax could coexist without compromising other markets. ) to the low ALA trait. Seeds were harvested from the pollen recipient plots up to a distance of 50 m in eight directions from the pollen donor. High ALA seeds were identified using a thiobarbituric acid test and served as a marker for gene flow. Binomial distribution and power analysis were used to predict the minimum number of seeds statistically required to detect the frequency of gene flow at specific a (confidence interval) and power (1Àb) values. As a result of the low frequency of gene flow, approximately 4 million seeds were screened to derive accurate quantification. Frequency of gene flow was highest near the source: averaging 0.0185 at 0.1 m but declined rapidly with distance, 0.0013 and 0.00003 at 3 and 35 m, respectively. Gene flow was reduced to 50% (O 50 ) and 90% (O 90 ) between 0.85 to 2.64 m, and 5.68 to 17.56 m, respectively. No gene flow was detected at any site or year 435 m distance from the pollen source, suggesting that frequency of gene flow was p0.00003 (P ¼ 0.95). Although it is not possible to eliminate all adventitious presence caused by pollen-mediated gene flow, through harvest blending and the use of buffer zones between GE and conventional flax fields, it could be minimized. Managing other sources of adventitious presence including seed mixing and volunteer populations may be more problematic.

Pollen-mediated gene flow from glyphosate-resistant common waterhemp (Amaranthus rudis Sauer): consequences for the dispersal of resistance genes

“…A power analysis reported by Jhala et al 43. using binomial probabilities was performed to determine the minimum sample size required to accept an outcome without losing the precision of the statistical tests (see SI materials and methods).…”

Transgenic flax/linseed (Linum usitatissimum L.) - expectations and reality

“…Other sources of possible contamination that must be mitigated include seed-mediated gene flow through certified flax seed; volunteer flax and inadvertent mixing of products within the transportation system (Jhala et al 2011). The study demonstrating effective mitigation strategies enabling the reduction doi: 10.17221/104/2015-CJGPB of seed-mediated gene flow from GM volunteer flax was published by Dexter et al (2010).…”

“…Cross-pollination between GM crops and wild weedy species was discussed in a number of publications Hall et al 2003;Warwick & Stewart 2005;Jhala et al 2008Jhala et al , 2009Jhala et al , 2011Griga et al 2008). Transgenes incorporated in the genomes of wild or weedy relatives of genetically modified cultural crops may cause changes in those populations.…”

Does flax have the answer to the GM mix-up?

“…Even so, flax is very much a 'C-list' member of the GM crop hall of fame and so the prospective characterisation of pollen-mediated gene flow between a (thus far nonexistent) GM flax variety and organic flax seems unlikely to set many pulses racing. However, it would be a mistake to dismiss the study by Jhala et al (2011, in this issue) on this basis, as there is a lot more to this work than first meets the eye. Unlike the plethora of similarly labelled counterparts that pervade the literature, this study does have the capacity to influence both policy and science.…”

“…To illustrate, although all member countries in the European Union are legally bound to the totally arbitrary 0.9% GM admixture tolerance threshold in non-GM seeds, political expediency coupled with uncertainty over the relative merits of sometimes contradictory pollen-mediated geneflow studies has contributed to significant variance in the isolation distances being imposed at the national level (Devos et al, 2009). However, Table 1 in this manuscript (Jhala et al, 2011) provides absolute guidance to the riskassessment researcher over the minimum sample size to assess for gene flow below set thresholds, with a given statistical power and confidence interval for use on flax. To my mind, the approach could be readily adapted to assemble similar tables for other crops.…”