Principles of Plant Genetics and Breeding

3 Germplasm evaluation. Markers can distinguish
homology and analogy. They can provide a common
measure of assessing divergence in germplasm.
Molecular markers have been used to assist in the
discovery of heterotic patterns in order to guide the
selection of parents for use in a hybrid breeding
program (e.g., in maize). Marker analysis (e.g., by
Roger’s distance) may be used to ascertain genetic
dissimilarity among lines of different heterotic groups
to enable the breeder to predict the performance of
hybrids to be developed from different intergroup
crosses.
4 Cultivar identification and protection. Molecular
markers may be used to fingerprint genotypes for the
protection of proprietary materials.
Breeding genetically modified cultivars
Steps in the breeding of conventional cultivars are
summarized in Figure 14.3a. The breeder starts by
assembling germplasm to create the base population.
Selection is practiced in the segregating population to
identify and advance the more desirable genotypes,
which are evaluated to identify and release the most
promising one as a commercial cultivar. A breeding
program can be implemented without oversight by any
entity, except at the stage of certification, when certifying
agencies inspect the product for conformity with set
standards.
On the other hand, breeding genetically modified
(GM) cultivars is a highly regulated activity, from inception
to completion of the project (Figure 14.3b). Before
biotechnology development and application activities
can proceed in a country, there has to be a national
biosafety policy in place (see Chapter 16). Furthermore,
the institution at which the breeding program is to be
conducted must also have its own institutional research
policy guidelines, prescribing procedures for conducting
research. Some of the guidelines pertain to the use
of hazardous materials. There are specific guidelines for
rDNA research (some variation may occur from one
institution to another).
Clearance
The first step in a genetic engineering project in the
USA is to submit the proposal to the local Institutional
Review Board and other specialized committees. (e.g.,
Institutional Biosafety Committee). These bodies review
the project materials and methods for scientific quality
and compliance with established safety and ethical
BIOTECHNOLOGY IN PLANT BREEDING 253
(a)
Assemble
germplasm
Create
variability
(cross)
Select
Evaluate
Release
cultivar
Procure GM
source
(b)
Establish appropriate
facilities (labs,
greenhouse, etc.)
Clearance with local
biosafety committee
Conduct research
Cross adapted parent
with GM parent
Apply for permit
for field evaluation
Federal
permit
Backcross
Evaluate in
greenhouse
Develop GM
source
State
permit
Petition for
non-regulation status to
commercialize product
Release for
commercialization
Figure 14.3 A comparison of the general steps involved
in breeding cultivars by (a) the conventional method and
(b) the use of genetic engineering technology. The specific
steps vary among breeders and situations.