Principles of Plant Genetics and Breeding

254 CHAPTER 14
guidelines. There has to be some provision for containment
and/or disposal of hazardous materials.
Depending on the nature of the project, a biosafety
level is assigned by the committee according to federal
guidelines.
The biosafety levels and their restrictions are as
follows:
BL1-P Basic containment level: restricted access to
greenhouse; insect, weed, and rodent control
mechanisms required; screens recommended.
BL2-P For agents of moderate potential hazard: BL1-
P requirements; plus concrete floor; screens
restricting movement of small insects but not
pollen; autoclave to sterilize transgenic materials
before removal.
BL3-P For agents of serious potential hazard: BL2-P
requirements; plus collection and sterilization
of liquid runoff; sealed windows; ventilation
filters; security fence; protective clothing.
BL4-P For work with extremely hazardous agents,
including certain exotic plant pathogens: similar
to BL3-P but more stringent.
Conduct research
Large seed companies such as Monsanto and Pioneer
develop their own GM breeding stock. They transfer
the gene of interest into the appropriate genetic background.
Other breeding programs may procure the
cloned gene or genetic stock at a fee, for use in their
projects. Developers of transgenic breeding lines must
evaluate them initially for:
1 Activity of the introduced gene (transgene).
2 Stable inheritance of the gene.
3 Unintended effects of the growth and development
of the plant.
Hybridize (cross)
Once an appropriate GM breeding line has been
obtained, it is crossed with a conventional adapted cultivar
to transfer the transgene into the desirable cultivar.
Backcross
The first cross is followed by cycles of repeated backcrosses
to the adapted cultivar to recover the traits of the
parent as much as possible. All these activities are conducted
under a restricted environment (greenhouse).
Evaluation
The breeder evaluates the success of the project in the
greenhouse. This may include evaluating the proper
expression of the transgene, yield and quality, and overall
performance of the new product.
Field testing
When the breeder is satisfied that the breeding project is
successful, the next step is to apply for permission to
field test the cultivar. An application to transport or
field test a transgenic plant is submitted to the Animal
and Plant Health Inspection Service (APHIS). Under
the Federal Plant Pest Act, APHIS must determine if a
transgenic plant variety has the potential to become a
pest (see Chapter 15).
Before permission is granted for field testing, some of
the basic criteria to be satisfied by the breeder include
presenting the following pieces of evidence to show:
1 Stable integration in the plant chromosome of the
transgene.
2 Non-pathogenicity to animals or humans.
3 Unlikely to be toxic to other non-target organisms.
4 Low risk of creating new plant viruses.
Field testing, if permission is granted, is conducted
at a number of locations and over several years. The
breeder should conduct the test in a manner that will
not permit contamination of the environment or food
supply system. At the end of the evaluation, a comprehensive
report is submitted to APHIS, including data
on the gene construct, effects on plant biology, effects
on the ecosystem, and spread of the gene to other
species. Depending on the product and its intended use,
other federal agencies (Food and Drug Administration,
Environmental Protection Agency) may be involved in
the process of field evaluation (see Chapter 15). In addition
to satisfying federal agency requirements, some
states may have their own regulations that must be
satisfied for field testing of GM varieties.
Commercialization
Once the field evaluation is successfully completed, the
breeder may apply for non-regulatory status to commercialize
the cultivar. If successful, the cultivar may
be released as a commercial cultivar to producers. Of
course, the breeder may seek appropriate protection
of the invention through patent application or other
appropriate measures.