Barley for Food and Health: Science, Technology, and Products

46 BARLEY BIOTECHNOLOGY: BREEDING AND TRANSGENICS
et al. 2004). The efforts to increase β-glucanase expression and activity have
major implications on improving the nutritional value of barley for poultry feeds
by negating the necessity of adding exogenous β-glucanase to the feed. From a
human nutritional standpoint, this has negative and positive connotations, as will
be discussed in Chapter 8.
In addition to the genetic engineering efforts listed above, 10 barley genes
were isolated by map-based cloning and at least 18 barley-specific patents were
applied for from 1997 through 2006 (Ganeshan et al. 2008). Protecting intellectual
property with patents has received considerable attention in recent years. It is
therefore not surprising that numerous patents, both issued and proposed, deal
with techniques for transformation of barley.
Transgenic Barley Risk: True or Imagined?
There are risks with regard to the safety of food products regardless of the method
used in the development, whether it is by one or more traditional methods or by
modern genetic engineering technology. A question often posed in opposition to
the use of transgenic technology in plants utilized for human food involves the
potential for movement of a transgene from the food into the human genome following
consumption of the food. The possibility of this occurring is quite remote,
nearly impossible in normal individuals. When the DNA and messenger ribonucleic
acid (RNA) of the target gene are ingested, they are broken down (digested)
to their basic components: purine or primidine bases (thymine, cytosine, adenine,
and guanine), a pentose sugar (ribose), and phosphoric acid. Thus, the genetic
material is no longer capable of functioning as a gene. Insertion of marker genes
that sometimes encode antibiotic resistance are used to identify the cells containing
the target gene. The use of marker genes designed in this manner has received
criticism due to the possibility of transferring antibiotic resistance to microflora
in the human gut. Aside from being subjected to enzymatic digestion, eukaryotic
cells are naturally resistant to most antibiotics that are targeted to bacteria, and
most antibiotics used in plant transformation are not currently used in medicine
(Tourte 2005). Resistance of gut bacteria to antibiotics has occurred, but it is more
likely to be due to overuse of antibiotics in clinical situations and in animal feed.
Behavior of a transgene when introduced into a new environment cannot be
predicted accurately. The behavior of a transgene may vary, resulting in amplification,
cosuppression, or disruption of a functional gene (Tourte 2005). Although
possible, the likelihood of activating toxins or creating allergens in an engineered
variety is no more likely than its occurrence in a plant created by classical breeding.
Despite the low likelihood, all engineered crops in commercial production are
tested exhaustively for substantial equivalence, meaning that they are identical to
the parent crop, with the exception of the trait introduced. If a gene is introduced
into a crop from a known allergenic source such as peanuts or wheat, FDA rules
state that the food must be labeled as containing the gene from that variety. Does
this mean that genetically engineered foods have zero risks? No, and this cannot
be said of foods created by classical breeding as well. This is exemplified by
certain potato and celery varieties created by classical breeding that were found