Non-target Effects of Hyperthermostable α-Amylase Transgenic Nicotiana tabacum in the Laboratory and the Field.

Ian Melville Scott,Hong Zhu,Amanda Follick,L Bruce Reynolds,Katherine Schieck,Rima Menassa

doi:10.3389/fpls.2019.00878

Ian Melville Scott, Hong Zhu + Show 4 more

Open Access

https://doi.org/10.3389/fpls.2019.00878

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Abstract

Thermostable α-amylases are important enzymes used in many industrial processes. The expression of recombinant Pyrococcus furiosus α-amylase (PFA) in Nicotiana tabacum has led to the accumulation of high levels of recombinant protein in transgenic plants. The initial steps to registering the transgenic tobacco at a commercial production scale and growing it in the field requires a risk assessment of potential non-target effects. The objective of this study was to assess the effect of feeding on transgenic tobacco with 2 indigenous insect species commonly associated with wild and commercial tobacco involving plants grown and evaluated under laboratory and field conditions. The highest levels of PFA ranged from 1.3 to 2.7 g/kg leaf fresh weight produced in the field-grown cultivars Con Havana and Little Crittenden, respectively. These two cultivars also had the highest nicotine (ranging from 4.6 to 10.9 mg/g), but there was little to no negative effect for either tobacco hornworm Manduca sexta L. or aphid Myzus nicotianae (Blackman). Both laboratory and field trials determined no short term (5 days) decrease in the survival or fecundity of the tobacco aphid after feeding on PFA transgenic tobacco compared to non-transgenic plants. In the field, tobacco hornworm larvae showed no differences in survival, final larval weights or development time to adult stage between transgenic lines of four cultivars and their corresponding wild type controls. Laboratory studies confirmed the field trial results indicating the low risk association of PFA expressed in tobacco leaves with tobacco hornworms and aphids that would feed on the transgenic plants.

Highlights

Evaluating the impact of transgenic or genetically modified (GM) crops to the environment poses unique challenges to the traditional risk assessment process
In the United States, stringent rules and regulations have been developed by the National Institutes of Health (NIH), the Department of Agriculture (USDA), the Animal and Plant Health Inspection Service (APHIS), the Environmental Protection Agency (EPA) and the Food and Drug Administration (FDA) that provide guidelines for testing and commercial release of GM crops
The combination of high nicotine and high Pyrococcus furiosus α-amylase (PFA) were not found to increase development time or reduce survival for hornworm fed in situ on field leaves for 7 days and field grown leaves until the larvae reached pre-pupal and adult stages

Summary

Introduction

Evaluating the impact of transgenic or genetically modified (GM) crops to the environment poses unique challenges to the traditional risk assessment process. Two new guidance documents introduce initiatives that examine ecological principles underlying ERA, such as the requirement of evaluating the whole GM plant, as well as the introduced traits, since the genetic modification may cause unintended changes to the plant’s phenotype that in turn might affect non-target organisms (Arpaia et al, 2017). This is important for new GM crops expressing new traits such as novel proteins as there can be altered plant metabolic pathways (e.g., starch production, oil composition, semiochemicals, etc.) that could cause possible secondary or indirect effects

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