Development and validation of gas chromatography and real-time quantitative PCR for the quantification of landscape-scale gene flow from varieties of high erucic acid (HEAR) oilseed rape

BACKGROUND: High erucic acid oilseed rape (HEAR) was tested as a source crop for estimates of regional geneflow. Two methods to detect HEAR in low erucic acid oilseed rape (LEAR) were compared: real-time quantitative PCR (qPCR) and gas chromatography (GC). RESULTS: Fields (2.5 ha) of a LEAR variety (0.028% EA) in Tayside and Hertfordshire were juxtaposed adjacent to and I km distant from a HEAR (44% EA) field. The LEAR variety was a varietal association to ensure high cross-pollination (CP). The methods were highly correlated, measuring between 30% and 0.5% CP. However, the qPCR method became unreliable below 0.5% CP, whereas GC was robust enough to detect raised EA equivalent to one F1 seed in 500 (0.2%). A statistical mixture model was fitted to the distributions of EA in samples in order to assign a CP value to each 500-seed sample. Declines of CP from 30% to < 1%, and EA from 5% to 0.2%, with distance up to 150 m in the near fields was best fitted with a power function. The combined mean EA for both far fields was 0.11%, well above the background LEAR value of 0.028%, and mean CP was 0.36%. CONCLUSIONS: The GC method of detection raised %EA should be a reliable and high-throughput means of estimating %CP between fields, provided the %EA of single F1 seed in receptor fields is measured to confirm the presence of F1 seed. (c) 2008 Society of Chemical Industry.