Principles of Plant Genetics and Breeding

Principles of organic plant breeding
The integrity approach to organic agriculture does
not imply that breeders cannot manipulate plants, but
rather that the tools and techniques used in breeding,
propagation, and cultivation of plants should not violate
this integrity. Integrity of plants pertains to characters
such as their nature, wholeness, species-specific characteristics,
and their being in balance with species-specific
environments.
Four levels of plant integrity have been proposed:
1 Integrity of life. This is defined as the state of wholeness
or completeness of a living organism that allows
it to perform all of its functions in a more or less
autonomous fashion. Consequently, crop cultural
practices that introduce synthetic chemicals may
interfere with this self-regulating capacity of the
plant, and hence be incompatible with organic
farming.
2 Plant-specific integrity. This is the state of wholeness
or completeness of a plant that allows it to perform
all of its plant-specific functions. Plants and
animals differ in specific ways at the cellular, whole
organism, and functional levels. Growing plants in
artificial environments (tissue culture, hydroponics)
infringes on the plant’s ability to perform its natural
functions (natural interaction with the soil). Using
techniques that reduce the natural reproductive
capacity of plants is unacceptable practice in organic
breeding. For example, using cytoplasmic male sterility
(CMS) without fertility-restorer genes will cause
the progeny from CMS hybrids to be sterile.
Ceccarelli, S. 1994. Specific adaptation and breeding for
marginal conditions. Euphytica 77:205–219.
Ceccarelli, S., and S. Grando. 1991. Environment of selection
and type of germplasm in barley breeding for stress conditions.
Euphytica 57:207–219.
Heaf, D., and J. Wirt. 2001. Intrinsic value and integrity of
plants in the context of genetic engineering. In: Proceedings
of the Ifgene Workshop, 9–11 May 2001 (Heaf, D.,
and J. Wirt, eds), pp. 32–35. Natural Sciences Section,
Dornach, Switzerland.
Lammerts van Bueren, E.T., M. Tiemens-Hulscher, J.
Jongerden, J.D. van Mansvelt, A.P.M. den Nijs, and G.T.P.
EMERGING CONCEPTS IN PLANT BREEDING 469
References and suggested reading
3 Genotypic integrity. This is defined as the state of
wholesomeness or completeness of the species-specific
genome. Plant breeding depends on variability for
success. Genotypic integrity is not violated as long as
the variation is natural in origin. However, genetic
engineering technology, which allows the transfer of
genes across natural barriers, breaches this integrity
principle.
4 Phenotypic integrity. This is defined as the state
of wholesomeness or completeness of an individual
plant, including its health. This principle is violated
when plants are developed (or cultivated) in a manner
that makes them unable to maintain themselves or
complete their life cycle in an organic production
system without chemical protection. Chemical mutagenesis
as a means of breeding violates this principle
simply because chemicals are used in the process.
Acceptable organic plant breeding techniques
In terms of creating variability, techniques that do not
violate the integrity of plants include crossing cultivars,
hybrid development with fertile F1 , testcrosses, backcrosses,
and bridge crossing. However, techniques at
the cell level (e.g., embryo cultures, somatic variation,
ovary culture) and the DNA level (e.g., genetic engineering,
protoplast fusion) are not acceptable.
In terms of methods of selection, mass selection,
pedigree selection, and even DNA diagnostics and
marker-assisted selection are considered compatible
with plant integrity. The diagnostic tools are acceptable
because they do not cause genetic modification of
plants.
Ruivenkamp. 1999. Sustainable organic plant breeding.
Louis Bolk Institute, Driebergen, the Netherlands.
Lammerts van Bueren, E.T., P.C. Struik, M. Tiemens-
Hulscher, and E. Jacobsen. 2003. Concepts of intrinsic
value and integrity of plants in organic plant breeding and
propagation. Crop Sci. 43:1922–1929.
Simmonds, N.W. 1984. Decentralized selection. Sugar cane
6:8–10.
Simmonds, N.W. 1991. Selecting for local adaptation in a
plant breeding program. Theor. Appl. Genet. 82:363–367.
Verhoog, H. 1992. The concept of intrinsic value and transgenic
animals. J. Agric. Environ. Ethics 5(2):147–160.