n the last decade, the genetic revolution in American crops has brought us corn that grows its own pesticide thanks to a lab-inserted bacterial gene, and tobacco that makes its own antifreeze using DNA from a North Atlantic flounder. This year, however, a University of Chicago biologist, Daphne Preuss, appears to have succeeded in creating a technology that will make existing genetic modifications of plants seem quaint. She inserted not single genes, but entire artificial chromosomes, into a batch of mustard plants.

A gene is a bit of DNA that instructs an organism how to make a single thing. Humans have a gene for eye color, for example. Each gene is like one page in the encyclopedia of instructions we call the genome. Like encyclopedias, genomes come in volumes – big chunks of DNA – called chromosomes. Human beings have 23. Corn has 10. A chromosome is the largest functional unit of genetic material smaller than the entire genome. 

Current genetic-modification techniques insert one gene into a plant’s natural chromosome, like sticking a sheet of paper into an encyclopedia. It’s a messy process full of random mistakes, and most biologists agree that the practical limit of the technology is two or three added genes per plant variety. Preuss has already beaten that limit by placing four extra genes together on their own chromosome – a slim genetic volume of her own writing. And once her techniques are perfected, there’s no reason to stop at 4, or 40, or even 400. 

What this means is that an individual plant could be genetically altered in a dazzling number of ways. Imagine a cucumber that resists both cold and drought, produces its own fungicide, herbicide and pesticide, has electric blue skin (or orange or mauve), tastes like barbecue sauce and grows to the exact circumference of a McDonald’s hamburger, so that it makes a perfect-sized pickle. All of these traits are possible using current technology, but you are limited to one or two tweaks per organism. With an artificial chromosome, you can throw them all – and more – into one cucumber.

Such radical modification of plants may not sound particularly appetizing. But the technology would undoubtedly be welcomed by many industries. For example, complex pharmaceuticals now synthesized by technicians in a lab could be grown much more cheaply inside crops altered with artificial chromosomes. An enterprising farmer could get into the business of selling ‘‘Cipro rice’’ – or, just as easily, ‘‘Cipro-Echinacea-Paxil-Claritin rice,’’ for when you’re having one of those days.

What about inserting artificial chromosomes in humans? It’s possible, but such complex alterations will clearly have to be carefully regulated. Making an electric blue baby, after all, raises ethical concerns that making an electric blue cucumber does not. Of course, environmental groups already have concerns with single-gene-added crops, which have killed innocuous butterflies and allegedly caused allergic reactions in humans. But scientists maintain that the improved control of artificial chromosomes will minimize such unintended consequences, even as they maximize, by orders of magnitude, the intended ones.