Assessment of potential impacts associated with gene flow from transgenic hybrids to Mexican maize landraces

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.Electronic supplementary materialThe online version of this article (10.1007/s11248-019-00160-3) contains supplementary material, which is available to authorized users.

Transgene behavior in Zea mays L. crosses across different genetic backgrounds: Segregation patterns, cry1Ab transgene expression, insecticidal protein concentration and bioactivity against insect pests

“…Many studies report that the mode of transgene inheritance follows directly a Mendelian segregation pattern [ 54 – 57 ] In maize, Duncan et al [ 58 ] reported that after GM traits were introgressed into landrace maize varieties the transgene segregated like other endogenous genes, following Mendelian principles,. In contrast, non-Mendelian segregation of transgenes has been reported in studies on rice [ 59 ], soybean [ 60 ], tobacco [ 61 ], wheat [ 62 ] and cotton [ 63 , 64 ].…”

Compositional Variation in Trans-Ferulic, p-coumaric, and Diferulic Acids Levels Among Kernels of Modern and Traditional Maize (Zea mays L.) Hybrids

“…In another study with yellow and white maize hybrids, a similar range of 4.4–5.16 μg/g dw was found ( 35 ). In hybrids derived by crossing a genetically modified parent with landraces, ranges were observed between 55.6 and 123.6 μg/g dw ( 32 ). However, further studies of specialty maize have found a higher value of soluble trans -ferulic acid in these varieties, especially in sweet corn ( 35 , 36 ).…”

“…For example, Xu et al ( 42 ) found that conventional hybrids contained a range of 84.79–239.33 μg/g dw, Venkatesh et al ( 43 ) found 232.58–532.51 μg/g dw, Harrigan et al ( 44 ) reported 84.15–259.68 μg/g dw, whereas the values in Classen et al ( 45 ) fluctuated between 29.3 and 219 μg/g dw. Duncan et al ( 32 ) reported that genetically modified hybrids crossed with landraces have ranges between 101.9 and 236.2 μg/g dw. The ILSI database covers most of these ranges and is a reliable alternative for comparison of bound p -coumaric acid ( 41 ).…”

“…Another study reported extensive variation between hybrids for bound trans -ferulic acid, having a four-fold range in values ( 45 ). Recently Duncan et al ( 32 ) reported that genetically modified hybrids crossed with landraces have a range between 1,150 and 2,530 μg/g dw. Landraces analyzed for bound trans -ferulic acid content, have also show different and wide variations; going from 394 to 1,700 μg/g dw ( 45 ), to higher values like 2,521–2,840 μg/g dw ( 27 ), or lower like 34–46 μg/g dw ( 30 ).…”

“…Phenolic acids have been associated with resistance to different pests, particularly, low levels of p-coumaric acid positively correlated to ear rotting (26). However, the evaluation of p-coumaric acid in its soluble form is not usually performed (27)(28)(29)(30)(31) as the major soluble phenolic compound in maize is trans-ferulic acid, although variable ranges are observed between 101 and 236 µg/g dw (32). This study shows that p-coumaric acid in its soluble form could potentially aid in the improvement of resistance to biotic stresses and should be included in future analyses for its evaluation.…”