Abstract
Genetically modified (GM) maize has been grown and safely consumed on a global scale since its commercialization in 1996. However, questions have been raised about the potential impact that GM maize could have on native maize landraces in Mexico, which is the center of origin and diversity of maize. This research was conducted to evaluate potential changes to maize landraces in an unlikely event of transgene introgression. For this study, two GM traits that confer insect protection and herbicide tolerance in maize (MON 89034 and MON 88017), designated as VT3Pro, were introgressed into two Mexican landraces, Tuxpeño and Tabloncillo. Field trials were conducted across four environments to assess phenotypic characteristics, plant response to stressors, and kernel composition of landraces with and without VT3Pro traits. Furthermore, materials from four backcrossing generations were analyzed for segregation of these GM traits. Generally, no significant differences were observed between landraces with and without VT3Pro traits for the evaluated characteristics and the segregation analysis showed that GM traits, when introgressed into landraces, followed Mendelian principles. These results support the conclusion that, if inadvertently introgressed into landraces, VT3Pro traits are not expected to alter phenotypic or kernel characteristics, plant response to stressors (except for targeted insect protection and herbicide tolerance traits) and would segregate like any endogenous gene. These results should be taken into consideration when discussing benefits and risks associated with commercial production of GM maize hybrids in the centers of origin and diversity of maize.
Highlights
Maize is an important crop grown over geographically diverse regions, climates, and soil types (Shiferaw et al 2011)
In 2015, genetically modified (GM) maize constituted a large portion of maize planted in the USA (92%), Brazil (88%), and Argentina (78%) with a total of 60.6 million hectares grown worldwide (ISAAA 2016)
Almost all GM maize planted globally contains insect protection and herbicide tolerance traits, either as single transgenes or stacked combination (ISAAA 2016). These and other GM traits have contributed to delivering higher yield, reducing chemical pesticide use, and increasing profitability (Brookes and Barfoot 2018a, b)
Summary
Maize is an important crop grown over geographically diverse regions, climates, and soil types (Shiferaw et al 2011). The global production of maize surpasses production of any other crop, having increased 5-fold over the past 56 years (FAOSTAT 2016). This remarkable increase in maize productivity is due to advances in agronomic practices, as well as advances in maize genetics like replacement of open-pollinated populations with maize hybrids and the introduction of biotechnology traits (Troyer 2006). Almost all GM maize planted globally contains insect protection and herbicide tolerance traits, either as single transgenes or stacked combination (ISAAA 2016). These and other GM traits have contributed to delivering higher yield, reducing chemical pesticide use, and increasing profitability (Brookes and Barfoot 2018a, b)
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