Iacomo Jonasson posted an update 3 months ago
This process can also cause significant reduction of genetic variation in the concerned populations, and may eventually pose threats to the conservation of the in situ conserved CWR populations. It is apparent through the above analyses that scientifically assessing the genetic and evolutionary impacts of transgene flow and introgression is very important Selleckchem Olaparib for the effective conservation of CWR populations. As an essential and first step, the assessment of gene flow frequencies from domesticated species under extensive cultivation to their wild relative species should be carried out systematically, as already started for some domesticated and wild species (Table 1). In relation to this assessment, we should determine whether CWR populations being considered for in situ conservation are geographically overlapped with domesticated species in the regions that are selected as an in situ conservation site, and whether the CWR populations being considered for in situ conservation share common flowering times to allow pollen-mediated crop-to-wild gene flow to happen (Lu et al., 2003; Lu & Snow, 2005; Lu, 2008; Lu & Yang, 2009). If the CWR populations in question overlap in geographical distribution and share flowering times with domesticated species, the actual crop-to-wild gene flow frequencies should be determined. For example, the identified gene flow frequencies from domesticated rice to its wild ancestral species (O. rufipogon) varied between 3% and 18% in the control field experiments, in which the frequencies were either assessed by applying molecular markers (Song et al., 2003) or a herbicide-resistance transgene (bar) as an identifier (Wang et al., 2006). In another study, Chen et al. (2004) reported a low level (<0.5%) of pollen-mediated gene flow from a GE rice line containing a herbicide-resistance transgene (bar) to weedy rice. These studies indicate that the probability of transgene introgression from transgenic rice to its wild relatives will be considerably high. Similar or even higher level of gene flow could be found from cultivated maize to its wild relative Teosinte, cultivated sorghum to wild Johnson grass, and pearl millet (Pennisetum glaucum (L.) R. Br.) to its wild relative (Pennisetum sieberanum (Schlecht.) Stapf & Hubb.) (see Table 1). These data, based on solid experiments, indicate that the phenomenon of pollen-mediated gene flow and introgression from domesticated species to their wild relative species is common worldwide, although the frequencies of gene flow can be variable. This situation poses a severe challenge for maintaining genetic diversity, genetic integrity, and evolutionary potential of in situ conserved CWR populations and species.