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

¹ University of Alberta, Department of Agricultural, Food and Nutritional Science, 410 Ag/Forestry Building, Edmonton, Alberta, T6G 2P5, Canada
² University of Alberta, Department of Biological Sciences, Z-1012 Biological Sciences Building, Edmonton, Alberta, T6G 2E9, Canada
³ Alberta Agriculture and Rural Development, J.G. O'Donoghue Bldg, 7000 – 113 St. Edmonton, Alberta, T6H 5T6, Canada
⁴ Alberta Agriculture and Rural Development, A252 Agriculture Centre, 100, 545401 – 1 Avenue S. Lethbridge, Alberta, T1J 4V6, Canada
⁵ CSIRO Plant Industry, Black Mountain, Australia

Corresponding author: linda.hall@ualberta.ca

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 non-transgenic 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.