is certainly much more of a barrier than the animal cell membrane, the fibers are sufficiently
strong and rigid to penetrate the plant cell wall. Also, because the chip surface is covered
with fibers, many cells can be targeted using a single chip. Early results with onion
epidermal cells show the utility of this approach (Chiera and McKnight, unpublished;
Fig. 10.12), but the high-efficiency delivery of DNA-coated nanofibers directly to the
nucleus of multiple plant cells remains a challenge.
10.6 The Rush to Publish
10.6.1 Controversial Reports of Plant Transformation
As with most areas of the sciences, breakthrough technologies are highly prized and quite
valuable. In addition to the notoriety that comes along with new discoveries, patent protec-
tion can provide a reasonable source of additional income, at least for university scientists.
Truly new ideas in the sciences are actually not very common, and most of the advances that
are reported in the scientific literature represent incremental improvements in preexisting
technology or small steps in our understanding of processes. When something really new
and novel does come along, it should be critically evaluated. Unfortunately, even in
science, this does not always happen. As a result, there are numerous reports in the literature
that initially cause quite a stir and then disappear because they did not work or worked with
such a low efficiency that they were deemed impractical. The plant transformation literature
is filled with reports like this. At the risk of alienating colleagues, some controversial reports
of plant transformation methods are listed below.
10.6.1.1. DNA Uptake in Pollen.For one of the first reports of plant transformation
(Hess 1980), pollen from a white-flowering petunia was soaked in DNA extracted from a
red-flowering petunia. When this soaked pollen was used to pollinate the white-flowering
petunia, some of the resulting seeds produced plants with either partially or fully red
flowers. The author concluded that the DNA must have been taken up by pollen and
passed onto the seedling from the fertilization process. The authors were cautious about
the interpretation of their work and reached their conclusions of transformation as the
most probable explanation of their results. They did the appropriate controls and noted
that a small amount of red pigmentation could occur in white flowers at certain times of
the year and in response to various stresses. Since that work was published over 25 years
ago, no one has been able to repeat this work, even after extensive efforts. The tools to
test for the presence of foreign DNA were not in existence at the time this work was
done and the red flower color was the only evidence for transformation. The most plausible
explanation for these results is pollen contamination, which the author discounted as they
had never observed this with any of their controls.
10.6.1.2 Agrobacterium-Mediated Transformation of Maize Seedlings
AlthoughAgrobacterium-mediated transformation of maize (Graves and Goldman 1986) is
now fairly routine, this early report ofAgrobacterium-mediated transformation of maize
tissues remains quite controversial. At the time of this report, there were a few claims of
Agrobacterium-mediated transformation of monocots and no reports for the economically
important cereals. In addition to a scientific publication, this work led to the issuance of
numerous patents. In this work, maize seedlings were wounded and inoculated with
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