Assessing gene flow from Bt cotton in Brazil and its possible consequences.

Abstract

This chapter addresses gene flow to wild relatives and its consequences. It reviews the evolutionary history of the genus Gossypium in relation to gene flow from cotton. It establishes the likely recipient populations of Gossypium and evaluates the likelihood of gene flow from G. hirsutum var. latifolium to potential recipient populations, the possibility of subsequent geographical spread of transgenes and the potential ecological effects resulting from gene flow.

Safety Assessment of Transgenic Organisms, Volume 4

“…The earliest archaeological evidence of the cultivation of G. barbadense dates to 5500 BC in northwestern Peru (Dillehay et al, 2007). This cotton species was apparently domesticated and grown extensively in the northwestern Peruvian and southwestern Ecuadorian region, and was spread into the Andes and farther eastward in South America, and onward to the Caribbean and southern Mesoamerica (Brubaker et al, 1999c;Vreeland, 1999;Pearsall, 2003;Westengen et al, 2005;Johnston et al, 2006;Dillehay et al, 2007).…”

“…Gossypium mustelinum is a local, very rare endemic in semi-arid northeastern Brazil (Freire et al, 1998; Batista et al, 2005;Barroso et al, 2006; WWF and IUCN, 1997), and is considered most similar to the original allotetraploid progenitor . Experimentally, G. mustelinum can form fertile F 1 as well as F 2 hybrids and backcrosses with G. hirsutum, and to some extent with G. barbadense (Freire, 2002b; Freire et al, 2002;Gardunia et al, 2007).…”

“…Spontaneous hybridisation of tetraploids in the New World Native populations of the three completely wild tetraploid species are widely separated biogeographically (Appendix 1). Moreover, the clearly genuinely wild native populations of G. barbadense and G. hirsutum are also completely separated from the other three species, and from each other (Brubaker and Wendel, 1994;Westengen et al, 2005;Johnston et al, 2006). Thus, fully natural hybridisations do not occur among the tetraploids; however, spontaneous (unaided) hybridisation might occur when cultivated plants are brought within range of these wild species or primordially wild populations.…”

“…Experimentally, G. mustelinum can form fertile F 1 as well as F 2 hybrids and backcrosses with G. hirsutum, and to some extent with G. barbadense (Freire, 2002b; Freire et al, 2002;Gardunia et al, 2007). The evidence of spontaneous introgression in Brazil is uncertain, and relates particularly to G. hirsutum Freire, 2002a; Freire et al, 2002; Borém et al, 2003;Johnston et al, 2006). …”

“…The next most distinct lineage is punctatum, and then latifolium. Of these three major domesticated lineages (Iqbal et al, 2001), marie-galante is a perennial, from which mocó cotton is still cultivated in Brazil (Freire and Moreira, 1991;Moreira et al, 1995;Johnston et al, 2006); punctatum and latifolium are annualised. The original Amerindian Hopi Moencopi cotton (Arizona, southwestern USA) is considered to belong to punctatum (Lee, 1984).…”