Molecular Plant Breeding 2024, Vol.15, No.5, 282-294 http://genbreedpublisher.com/index.php/mpb 289 Table 1 Studies testing for fitness costs of resistance toBt maize by western corn rootworm (Adopted from Gassmann, 2021) Type of resistance 1 Strain Resistant to toxin 2 Cost present? 3 Traits affected4 Laboratory selected Brookings moderately selected Cry3Bb1 No ----- Laboratory selected Brookings moderately selected (Strain1) Cry3Bb1 No ----- Laboratory selected Brookings moderately selected (Strain2) Cry3Bb1 No ----- Laboratory selected Brookings moderately selected (Strain3) Cry3Bb1 No ----- Laboratory selected Moderately selected (Strain1) Cry3Bb1 No ----- Laboratory selected Brookings moderately selected (Strain2) Cry3Bb1 No ----- Laboratory selected Data presented as composite of three resistant strains CryBb1 Yes Fecundity; adult (male) longevity Laboratory selected Brookings moderately selected CryBb1 No ----- Laboratory selected Brookings moderately selected CryBb1 Yes Larval development; egg viability Laboratory selected mCry3A selected mCry3A No ----- Laboratory selected eCry3.1Ab selected eCry3.1Ab No ----- Field evolved Hopkinton Cry3Bb1 No ----- Field evolved Cresco Cry3Bb1 Yes Larval development; survival to adulthood; fecundity Field evolved Elma Cry3Bb1 Yes Larval development Field evolved Monona Cry3Bb1 No ----- Field evolved Cresco Cry3Bb1 Yes Decline in resistance over time Field evolved Hopkinton Cry3Bb1 Yes Decline in resistance over time Field evolved Data presented as composite of eight resistant strains Cry3B1 Yes Adult Size Note: 1 Describes whether a strain was generated by selecting a susceptible stain on Bt maize in the laboratory (laboratory selected) or was generated fromBt-resistant insects collected from the field (field evolved). 2 Type of Bt maize on which the rootworm strain was selected and to which it was resistant. 3 States whether fitness costs of Bt resistant were detected for a specific strain in a study. 4 Life-history traits for which a fitness cost was detected or cases where resistance declined over time when a stain was not exposed to Bt maize (Adopted from Gassmann, 2021) 9 Challenges and Limitations of Genetic Engineering in Maize Breeding 9.1 Regulatory hurdles and intellectual property concerns The regulatory landscape for genetically engineered crops is complex and often fraught with delays and political interference. The process for regulatory approval is slow and costly, which can significantly hinder the commercialization of genetically modified maize varieties. For instance, the approval process for ‘Roundup Ready’ alfalfa in the US involved several rounds of regulation, deregulation, and re-regulation, illustrating the bureaucratic challenges faced by developers of genetically engineered crops. Additionally, the stringent regulatory requirements can be a major barrier to the adoption of new technologies, as seen in the limited commercialization of transgenic forage, turf, and bioenergy crops. Intellectual property concerns also pose significant challenges, as the proprietary nature of many genetic engineering technologies can limit access and increase costs for breeders and farmers (Herman et al., 2020). 9.2 Potential risks and unintended consequences: ecological and health concerns Genetic engineering in maize breeding raises concerns about potential ecological and health risks. Unintended effects, such as changes in the transcriptome and metabolome, can occur, although studies have shown that these effects are often comparable to those observed in conventional breeding (Huang et al., 2022). However, the potential for unintended ecological impacts, such as gene flow to wild relatives and non-target effects on other
RkJQdWJsaXNoZXIy MjQ4ODYzMg==