ananyo writes "A genetic-modification technique used widely to make crops herbicide resistant has been shown to confer advantages on a weedy form of rice, even in the absence of the herbicide. Used in Monsanto's 'Roundup Ready' crops, for example, resistance to the herbicide glyphosate enables farmers to wipe out most weeds from the fields without damaging their crops. A common assumption has been that if such herbicide resistance genes manage to make it into weedy or wild relatives, they would be disadvantageous and plants containing them would die out. But the new study led by Lu Baorong, an ecologist at Fudan University in Shanghai, challenges that view: it shows that a weedy form of the common rice crop, Oryza sativa, gets a significant fitness boost from glyphosate resistance, even when glyphosate is not applied. The transgenic hybrids had higher rates of photosynthesis, grew more shoots and flowers and produced 48 — 125% more seeds per plant than non-transgenic hybrids — in the absence of glyphosate, the weedkiller they were resistant to."