title: The effect of Bt-transgene introgression on plant growth and reproduction in wild Brassica juncea.
abstract: This study aims to investigate the relative plant growth and reproduction of insect-resistant and susceptible plants following the introgression of an insect-resistance Bt-transgene from Brassica napus, oilseed rape, to wild Brassica juncea. The second backcrossed generation (BC2) from a single backcross family was grown in pure and mixed stands of Bt-transgenic and non-transgenic siblings under two insect treatments. Various proportions of Bt-transgenic plants were employed in mixed stands to study the interaction between resistant and susceptible plants. In the pure stands, Bt-transgenic BC2 plants performed better than non-transgenic plants with or without insect treatments. In mixed stands, Bt-transgenic BC2 plants produced fewer seeds than their non-Bt counterparts at low proportions of Bt-transgenic BC2 plants in the absence of insects. Reproductive allocation of non-transgenic plants marginally increased with increasing proportions of Bt-transgenic plants under herbivore pressure, which resulted in increased total biomass and seed production per stand. The results showed that the growth of non-transgenic plants was protected by Bt-transgenic plants under herbivore pressure. The Bt-transgene might not be advantageous in mixed stands of backcrossed hybrids; thus transgene introgression would not be facilitated when herbivorous insects are not present. However, a relatively large initial population of Bt-transgenic plants might result in transgene persistence when target herbivores are present.
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Beijing, 100093, China.
authors.forename: Yong-Bo
authors.initials: YB
authors.lastname: Liu
authors.forename: Henry
authors.initials: H
authors.lastname: Darmency
authors.forename: C Neal
authors.initials: CN
authors.lastname: Stewart
authors.forename: Wei
authors.initials: W
authors.lastname: Wei
authors.forename: Zhi-Xi
authors.initials: ZX
authors.lastname: Tang
authors.forename: Ke-Ping
authors.initials: KP
authors.lastname: Ma
mesh_terms: D029688:Brassica napus / Q000235:genetics; D051456:Gene Flow; D060434:Herbivory; D006824:Hybridization, Genetic; D009149:Mustard Plant / Q000235:genetics* / Q000254:growth & development*; D030821:Plants, Genetically Modified; D012639:Seeds / Q000235:genetics / Q000254:growth & development; D019076:Transgenes