Hybridisation within Brassica and allied genera: evaluation of potential for transgene escape

Abstract

Determining the potential for hybridisation between transgenic crops and their relatives is a major component of risk assessment. Recent assessments of the extent of reproductive compatibility between crops and their relatives draw heavily on existing data from experimental crosses to infer the likelihood of hybridisation and introgression. Since the literature in this area continues to grow at a rapid pace, it is essential that such analyses can be easily updated. We used a database approach to assemble data on reproductive compatibility for eight crop species in Brassica, Raphanus and Sinapis, using data from hand pollination, spontaneous (unassisted) pollination and trials using in vitro techniques (e.g. embryo rescue), incorporating 326 studies and 216 species combinations. We found many reports for major crop species (B. juncea, B. napus, B. oleracea and B. rapa), but fewer for minor crops (B. carinata, B. nigra, Raphanus sativus and Sinapis alba). Many species combinations remain untested, and we highlight these information gaps. While reproductively incompatible species can be discounted as targets for transgene escape, compatible species must be evaluated further in the particular context where transgenic crops are grown. Because the data is retained in a database in a relatively unmodified form, multiple views of the data can be generated; this review represents one possible view of this data. Our approach also allows new data to be easily incorporated into future reanalyses and can be extended to other crop groups, and as such is a useful method of assembling, analysing and sharing data for risk assessment.

Monitoring the occurrence of genetically modified oilseed rape growing along a Japanese roadside: 3-year observations

“…Some of these vegetables are left unharvested and flower in the following spring. Interspecific hybridization between Brassica crops can occur under natural conditions, although the results of hybridization potential differ among various reports (e.g., Chèvre et al, 2004;FitzJohn et al, 2007;Ford et al, 2006;Jørgensen et al, 1996;Légère, 2005;Sheffler and Dale, 1994;Stewart et al, 2003;Warwick et al, 2003;Wilkinson et al, 2003). Allainguillaume et al (2006) reported that the fitness decline of hybrids between B. napus and B. rapa in the United Kingdom acted as a means of natural biological containment.…”

Plant fitness assessment for wild relatives of insect resistant crops

“…Pollen transfer is likely for flowering oilseed rape and also possible for vegetable crop fields (broccoli and cabbage), where there can be occasional early flowering individuals, post-harvest remnant flowering plants, early bolting or unharvested fields, and flowering foundation seed crops. Oilseed rape (B. napus) readily hybridizes in the field with B. rapa (FitzJohn et al, 2007;Jorgensen and Andersen, 1994;Warwick et al, 2003), and Bt transgenes are stably expressed in these crop-wild hybrids (Zhu et al, 2004). Crosses between B. oleracea and wild relatives have been much less studied, so it is difficult to determine a probability of spontaneous hybridization with wild relatives in the field beyond its apparent compatibility with naturalized B. oleracea in our region (Letourneau et al, 2002).…”

The Biology of Canadian Weeds. 137. Brassica napus L. and B. rapa L.

“…Interspecific studies which successfully used conventional sexual crosses to produce F 1 hybrids are summarized in Table 5 and recently summarized and evaluated with regards to potential for transgene escape in an extensive review by Fitzjohn et al (2007). Many other hybridizations with more distant relatives have been accomplished using embryo, ovary or ovule rescue techniques (reviewed in Warwick et al 2000).…”