Pollen-mediated gene flow from transgenic safflower (CarthamustinctoriusL.) intended for plant molecular farming to conventional safflower

Abstract

Field experiments were conducted in Chile and western Canada to measure short-distance (0 to 100 m) outcrossing from transgenic safflower (Carthamus tinctorius L.) intended for plant molecular farming to nontransgenic commodity safflower of the same variety. The transgenic safflower used as the pollen source was transformed with a construct for seed-specific expression of a high-value protein and constitutive expression of a gene conferring resistance to the broad-spectrum herbicide glufosinate. Progeny of non-transgenic plants grown in plots adjacent to the transgenic pollen source were screened for glufosinate resistance to measure outcrossing frequency. Outcrossing frequency differed among locations: values closest to the transgenic pollen source (0 to 3 m) ranged from 0.48 to 1.67% and rapidly declined to between 0.0024 to 0.03% at distances of 50 to 100 m. At each location, outcrossing frequency was spatially heterogeneous, indicating insects or wind moved pollen asymmetrically. A power analysis assuming a binomial distribution and a range of alpha values (type 1 error) was conducted to estimate an upper and lower confidence interval for the probable transgenic seed frequency in each sample. This facilitated interpretation when large numbers of seeds were screened from the outcrossing experiments and no transgenic seeds were found. This study should aid regulators and the plant molecular farming industry in developing confinement strategies to mitigate pollen mediated gene flow from transgenic to non-transgenic safflower.

A mechanistic model of pollinator-mediated gene flow in agricultural safflower

“…The model estimates of MFG in safflower are consistent with available data, which have been collected only in experimental arrays much smaller than a typical agricultural field (McPherson et al, 2009). Accounting Q2 for patch size (Fig.…”

“…(1) to safflower, the units of c are capitula, rather than fruit, but the same model applies, even if multiple pollinator visits are required to fully fertilize the seed-bearing structure (Cresswell, 2003). Previous measurements of gene flow in safflower were made in plots of less than 1 ha (Deokar & Patil, 1976;McPherson, Good, Topinka, Yang, McKenzie et al, 2009). In contrast, my analysis estimates the possible levels of gene flow via insect-mediated cross-pollination into fields covering tens of hectares, which typify agricultural safflower in North America.…”

Hybridization between GM soybean (Glycine max(L.) Merr.) and wild soybean (Glycine sojaSieb. et Zucc.) under field conditions in Japan

“…Although we expected that the presence of other wild soybean walls would assist in minimizing hybridization, we were not able to detect an effect. The effectiveness of buffer plants to reduce hybridization between GM and non-GM crops has been documented for other insect-pollinated crops, such as oilseed rape (Morris et al, 1994;Staniland et al, 2000) and safflower (McPherson et al, 2009). Buffer plants are also likely effective in reducing hybridization between GM soybean and their wild relatives, but further studies will be required quantify this effect.…”

Short communication. Estimation of cross-fertilization rate in saff lower (Carthamus tinctorius L.)

“…In this sense, Rudolphi et al (2008) estimated an outcrossing rate between 29.9 and 63.1% within plots at a plant density of 40 plants m -2 and an outcrossing rate from 6.5 to 18.1% between plots in a study conducted in Germany. McPherson et al (2009) studied pollen flow at different distances at locations in Canada and Chile. They found outcrossing frequencies between 0.5 and 1.7% at plant distances between 0.3 and 3 m and decreasing frequencies at longer distances, resulting in values lower than 0.05% at distances between 50 and 100 m. Additionally, the authors found that the outcrossing frequency was spatially heterogeneous, indicating asymmetrical pollen distribution.…”

“…Chi-square values were 217.6 (p < 0. The extent of cross-fertilization in safflower depends upon genotypes and environmental conditions (McPherson et al, 2009). The present study was conducted in a typical Mediterranean location using two cultivars adapted to this environment.…”