1920s. Even then, it was used to transport a fraction of long-distance passengers. Trains,
ships, and automobiles were far more popular. There were many safety concerns in the
early days of air travel, and safety considerations are still a big part of air travel. It is a
highly regulated business, but one with clear markets and benefits. Aside from the invention
and application of the jet engine, most of the improvements in air travel were incremental.
Materials, fuel, avionics, and a whole host of other components gradually got better.
Finally, there was a stasis of innovation. In the 1950s and the 1960s, commercial aircraft
reached a level of form and function that differs little from that of currently used airplanes.
Of course, the electronics of today’s Boeing 737 are different from those of the one that first
flew in 1965, but it is still a 737 in design and product. Innovation has not ceased in aircraft,
but it no longer seems very transformative. Indeed, some revolutionary developments were
not sustainable. For example, in the 1960s it was apparent that supersonic commercial air
travel was feasible, and indeed, seemingly the future of airlines. Several companies raced to
develop the first commercial supersonic jet, and the Concorde won. But few people could
afford the high cost of airfare, and the last Concorde was parked earlier this decade as safety
concerns combined with prohibitive expenses overtook innovation. Advanced technology
in and of itself is not sufficient for commercialization. For subsonic jet travel, safety con-
cerns are still with us, but the current air travel technology is generally accepted; indeed,
it is deemed as a necessary component of modern life. That is because the 737 works
quite effectively and is economically sustainable. One might argue that transgenic plants,
in their current form, are much like the 737; at least the version of the 1960s. Both of
these function fine, but key improvements do make a difference.
In that spirit, there are still some crucial incremental biotechnological innovations that
are on the horizon worth mentioning here. Perhaps not all will be implemented into final
products—they might be too “supersonic,” but we can see patterns of technologies emer-
ging that we think will make a difference. This chapter does not cover new and novel pro-
ducts. It is clear that pharmaceuticals will be produced in plants, transgenic plants will be
used in phytoremediation and phytosensing, and plant biotechnology will be important for
bioenergy production. These are all exciting, but what is happening on the technology side
that bears watching? A few innovations will be introduced here as a finale to this book.
16.2 Site-Specific Recombination Systems to Provide Increased Precision
As new technologies are developed, offering greater control over the placement and content
of the DNA introduced into the plant genome, many of these innovations will eventually
find their way into future generations of GM (genetically modified) plants. Greater engin-
eering precision could help alleviate some biosafety concerns, but more importantly,
advances in precision engineering will be adopted for its intrinsic value, since they
enable complex engineering tasks to be achieved with greater speed and less effort.
Advances in the way DNA is introduced into a plant will likely benefit from break-
throughs in geneticrecombination-basedmethods that were introduced in Chapter 7.
Recall that when DNA is introduced into a cell nucleus, it may recombine into the
genome by either homologous or nonhomologous processes, mediated by host proteins
that repair DNA damage. In homologous recombination, the damaged DNA is repaired
faithfully by incorporating or copying the template from a homologous source, such as
that in a homologous chromosome or sister chromatid. In nonhomologous recombination,
16.2. SITE-SPECIFIC RECOMBINATION SYSTEMS TO PROVIDE INCREASED PRECISION 359