Perhaps I am mistaken, but as I understand it, patents are commonly used for the seeds and plants themselves, but I'm talking about patented genes specifically, as they would spread more easily than whole seed or plants.Wow! Where have you been? Patents WERE issued years ago and ARE being enforced against farmers across the world - see 2004 patent infringement paper
As is- assuming the law is actually followed, of course- someone has to unwisely agree to Monsanto's TUA and then contractually backs themselves into a corner, but if genes themselves were patented, and a GM population were to crossbreed with another population, the patented genes could then end up in crop or livestock populations whose owner never agreed to use the patented genes but could still be sued for royalties at all stages of production. At least with seeds floating in, you could ideally remove those troublesome seeds and plants, but if patented genes make their way into a population, you're screwed until the patent expires, which could take a decade or two, or you'd have to completely kill off that particular, compromised population.
If I'm still missing something, tell me, but I think we're talking about different applications of poor patents.
It's kind of a neat idea for a bad sci-fi novel though, isn't it? Genetically engineer incredibly fertile plants, perhaps ones closely related to popular crops, allowing your patented genes to spread all over the place, and then, a few years down the road, start tossing lawsuits left and right.
If only I could work in a gunfight somewhere...