Dissertation Research: Evaluating the Effects of Genetically Modified Bt Maize on Symbiotic Arbuscular Mycorrhizal Fungi in the Soil Ecosystem

自1996年以来，转基因玉米已被商业化种植，目前占美国种植的所有玉米的80%。虽然转基因作物被广泛种植，但这项技术的环境影响尚未得到彻底评估。波特兰州立大学的研究人员正在使用转基因Bt玉米来研究植物生物技术的进步如何影响土壤环境中植物和共生生物之间的重要相互作用。转基因Bt玉米产生一种杀虫毒素，这种毒素与土壤颗粒结合，并随着时间的推移在环境中积累。由于土壤微生物对有机物的分解、养分的再循环以及与植物形成共生关系至关重要，因此确定转基因作物生产在土壤中的影响非常重要。已知健康的植物-微生物相互作用可以刺激植物生长，提高水和养分的可用性，并帮助植物度过干旱，疾病和营养胁迫。这种共生关系的任何中断都可能对整个土壤和植物健康产生负面影响，需要额外的化学投入来维持这些系统的生产力。本论文的研究将探讨在田间条件下转Bt基因玉米是否减少了共生植物-真菌的关系，并评估Bt作物生产对土壤生态系统中共生丛枝菌根真菌的丰度和多样性的影响。虽然在农业中使用生物技术有许多好处，如减少广谱农药的使用，但很少有人研究转基因作物生产对土壤中共生微生物的影响。随着全球转基因作物种植面积的持续增加，研究转基因作物对土壤群落的非目标影响变得更加重要。这项研究评估了农业生物技术对土壤环境的好处和潜在影响，目的是在使用转基因作物和保护健康的土壤生态系统之间找到一个可接受的平衡。

Genetically modified (GM) corn has been grown commercially since 1996 and now constitutes 80% of all corn grown in the United States. Although GM crops are cultivated widely, the environmental effects of this technology have not been thoroughly evaluated. Researchers at Portland State University are using genetically modified Bt corn to investigate how advances in plant biotechnology affect the important interactions between plants and symbiotic organisms in the soil environment. Transgenic Bt corn produces an insecticidal toxin that binds to soil particles and accumulates in the environment over time. Because soil microorganisms are critical for decomposing organic matter, recycling nutrients, and forming symbiotic relationships with plants, it is important to determine the effects of transgenic crop production in the soil. Healthy plant-microbe interactions are known to stimulate plant growth, enhance water and nutrient availability, and help plants survive drought, disease, and nutrient stress. Any disruption in this symbiotic relationship is likely to have negative effects on overall soil and plant health, requiring additional chemical inputs to maintain productivity in these systems. This dissertation research will examine whether symbiotic plant-fungal relationships are reduced in transgenic Bt corn under field conditions and assess the effects of Bt crop production on the abundance and diversity of symbiotic arbuscular mycorrhizal fungi in the soil ecosystem. Although there are many benefits of using biotechnology in agriculture, such as reduced broad-spectrum pesticide use, little research has been done on the effects of transgenic crop production on symbiotic microorganisms in the soil. Examining non-target effects of GM crops on the soil community becomes even more important as transgenic crop acreage continues to increase globally. This research evaluates both the benefits and potential impacts of agricultural biotechnology on the soil environment with the goal of finding an acceptable balance between the use of genetically engineered crops and the preservation of a healthy soil ecosystem.