Green Chemistry and the Ten Commandments

276 Green Chemistry, 2nd ed

Future Crops

The early years of transgenic crops can be rather well summarized by soybeans,
corn, and cotton resistant to herbicides and insects. In retrospect, these crops will almost
certainly seem rather crude and unsophisticated. In part, this lack of sophistication is
due to the fact that the genes producing the desired qualities are largely expressed by all
tissues of the plants and throughout their growth cycle, giving rise to problems such as
the Bt-contaminated corn pollen that may threaten Monarch butterflies or Bt-containing
potatoes that may not be ideal for human consumption. It is anticipated that increasingly
sophisticated techniques will overcome these kinds of problems and will lead to much
improved crop varieties in the future.
A wide range of other transgenic crops are under development. One widely
publicized crop is “golden rice” which incorporates b-carotene in the grain, which is
therefore yellow, rather than the normal white color of rice. The human body processes
b-carotene to Vitamin A, the lack of which impairs vision and increases susceptibility
to maladies including respiratory diseases, measles, and diarrhea. Since rice is the main
diet staple in many Asian countries, the widespread distribution of golden rice could
substantially improve health. As an example of the intricacies of transgenic crops, two of
the genes used to breed golden rice were taken from daffodil and one from a bacterium!
Some investigators contend that humans cannot consume enough of this rice to provide
a significant amount of Vitamin A.
One of the first transgenic crops designed for human consumption was a variety
of tomato that ripened slowly and could be left on the vine longer than conventional
tomatoes, thus developing a better flavor than other varieties, which are normally picked
while still green. Unfortunately the genetically engineered variety, which was given
the brand name of FlavrSavr, did not have other desirable characteristics and failed.
Work is continuing on delayed-ripening tomatoes and on improving the nutritional value
of tomatoes, such as by raising the content of lycopene, which is involved with the
production of Vitamin A.
Work continues on improved transgenic oilseed crops especially canola, which
produces canola oil. Efforts are underway to modify the distribution of oils in canola
to improve the nutritional value of the oil. Another possibility is increased Vitamin E
content in transgenic canola. Sunflower, another source of vegetable oils, is the subject
of efforts to produce improved transgenic varieties. Herbicide tolerance and resistance to
white mold are among the properties that are being developed in transgenic sunflowers.
Decaffeinated coffee and tea have become important beverages. Unfortunately, the
processes that remove caffeine from coffee beans and tea leaves also remove flavor,
and some such processes use organic solvents that
may leave undesirable residues. The genes that
produce caffeine in coffee and tea leaves have now
been identified, and it is possible that they may
be removed or turned off in the plants to produce
coffee beans and tea leaves that give full-flavored
products without the caffeine. Additional efforts

N

C

N

C

C

C N

C

N

O

O

CH 3

H 3 C

H

CH 3

The caffeine

molecule