@MeiselZachary (for ex, if the GMO gene makes the crop susceptible to a blight that gets introduced and spreads widely... you'd want to be able to shift to a variety without that gene, maybe use it to make a new GMO with a different gene)
@MeiselZachary Another complaint is more about one way GMO is used in practice- which is to make the crop immune to a pesticide so the field can be sprayed to kill everything except the crop...
@MeiselZachary Permaculture says that indiscriminate use of pesticides kills both plant-eating pests and the predators which in nature keep them in check... But the pests rebound faster than the predators so you have a bigger problem the next year, requiring increasing chemical applications