Gene flow from transgenic oilseed Brassica juncea (L.) Czern. into weedy Sinapis arvensis L. (wild mustard)

Abstract

AbstractGene flow from acetolactate synthase‐resistant (HR) Brassica juncea oilseed canola to related weed, Sinapis arvensis (density 1 plant/m2) was assessed in a 100 m2 field plot of HR B. juncea. Two HR F1 hybrids (H1 and H2) were detected among 109 951 seedlings screened with imazethapyr (hybridization frequency – 1.8 × 10−5). Hybridity was confirmed using flow cytometry, B. juncea‐specific amplified fragment length polymorphisms (AFLPs) markers, genomic in situ hybridization (GISH) and PCR‐based detection of B. juncea's HR gene. H1 and H2 had 2n = 27 and 2n = 45 chromosomes, corresponding 3x (SrAB) and 5x (SrAABB) genomic structures and reduced male fertility, 3.2 and 16.6% pollen viability, respectively. H1 was self‐incompatible, whereas H2 set seed when selfed (B. juncea trait). Selfed F2, F3 and F4 plants showed HR trait persistence and vigorous growth and high (80–100%) pollen fertility in 22% and 39% of the F2 and F3 plants, respectively. No progeny were obtained from F1, F2 or F3 hybrids × S. arvensis backcrosses, suggesting the likelihood of introgression of traits is low to negligible.