title: Transgenes for insect resistance reduce herbivory and enhance fecundity in advanced generations of crop-weed hybrids of rice.
abstract: Gene flow from transgenic crops allows novel traits to spread to sexually compatible weeds. Traits such as resistance to insects may enhance the fitness of weeds, but few studies have tested for these effects under natural field conditions. We created F 2 and F 3 crop-weed hybrid lineages of genetically engineered rice (Oryza sativa) using lines with two transgene constructs, cowpea trypsin inhibitor (CpTI) and a Bt transgene linked to CpTI (Bt/CpTI). Experiments conducted in Fuzhou, China, demonstrated that CpTI alone did not significantly affect fecundity, although it reduced herbivory. In contrast, under certain conditions, Bt/CpTI conferred up to 79% less insect damage and 47% greater fecundity relative to nontransgenic controls, and a 44% increase in fecundity relative to the weedy parent. A small fitness cost was detected in F 3 progeny with Bt/CpTI when grown under low insect pressure and direct competition with transgene-negative controls. We conclude that Bt/CpTI transgenes may introgress into co-occurring weedy rice populations and contribute to greater seed production when target insects are abundant. However, the net fitness benefits that are associated with Bt/CpTI could be ephemeral if insect pressure is lacking, for example, because of widespread planting of Bt cultivars that suppress target insect populations.
authors.affiliation: Ministry of Education Key Laboratory for Biodiversity and Ecological Engineering, Institute of Biodiversity Science, Fudan University Shanghai, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Yang
authors.affiliation: Ministry of Education Key Laboratory for Biodiversity and Ecological Engineering, Institute of Biodiversity Science, Fudan University Shanghai, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Xia
authors.affiliation: Ministry of Education Key Laboratory for Biodiversity and Ecological Engineering, Institute of Biodiversity Science, Fudan University Shanghai, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Fujian Province Key Laboratory of Genetic Engineering for Agriculture, Fujian Academy of Agricultural Sciences Fuzhou, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.affiliation: Fujian Province Key Laboratory of Genetic Engineering for Agriculture, Fujian Academy of Agricultural Sciences Fuzhou, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Su
authors.affiliation: Department of Evolution, Ecology & Organismal Biology, Ohio State University Columbus, OH, USA.
authors.forename: Allison A
authors.initials: AA
authors.lastname: Snow
authors.affiliation: Ministry of Education Key Laboratory for Biodiversity and Ecological Engineering, Institute of Biodiversity Science, Fudan University Shanghai, China.
authors.forename: Bao-Rong
authors.initials: BR
authors.lastname: Lu
keywords: biosafety; biotechnology; competition; genetically engineered; introgression; red rice; risk assessment; weediness