General background on technical aspects
Julia Borys
COBORU
Head of DUS Testing Department
Introduction
The legal protection of plant varieties is a particular form of intellectual property
protection in plant care and seed production.
The exclusive right to a plant variety is recognised following an application from the
breeder. The following criteria should be fulfilled in order for the legal protection to be
granted:
Technical criteria:
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the plant variety must be distinct, uniform and stable.
Formal criteria:
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the plant variety must fulfil the criteria of novelty;
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the plant variety must have a suitable denomination;
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the breeder must comply with the required formalities with regard to the office granting
protection and payment of the fees stipulated by law.
The UPOV Convention allows for protection to be granted following an investigation of
the plant variety, which must be tailored to the specific requirements of each taxon.
The UPOV guidelines for testing the distinctiveness, uniformity and stability (DUS) of
new plant varieties present common ground for the member states (currently 61) in the
preparation of methodologies, carrying out field studies in so-called DUS testing and creating
a description of the plant variety in a unified form. DUS testing makes it possible to describe
a plant variety and its identification, which is useful in the case of infringement of right in
relation to the protected plant variety.
The breeder of the protected plant variety (the holder of the plant variety right) may
demand the protection of their right thereto, if they are able to prove that the plant material in
question does not differ from the protected plant variety.
This document aims to provide a general background of the technical aspects that are
important for the legal protection of plant varieties. It contains the following issues:
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Notion of plant variety;
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General remarks with regard to DUS testing;
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Testing and evaluation of distinctiveness;
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Testing and evaluation of uniformity;
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Testing and evaluation of stability;
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New techniques;
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Execution of exclusive right to the plant variety;
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Applications.
Notion of plant variety
In accordance with the UPOV Convention, plant variety is defined as follows:
"Variety" means a plant grouping within a single botanical taxon of the lowest known
botanical rank, which, irrespective of whether the conditions for the grant of a plant variety
right are fulfilled or not, may be:
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defined by the expression of characteristics resulting from a given genotype or
combination of genotypes,
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distinguished from other plant groupings by the expression of at least one of the said
characteristics, and
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which is considered as a unit with regard to its suitability for being propagated
unchanged.
It results from the definition of a plant variety that it is defined by the expression of its
characteristics. The breeder lists the most important characteristics (traits) of the plant in the
application for registering the plant variety right.
Testing distinctiveness, uniformity and stability, based on the observation and
description of the characteristics makes it possible to confirm whether the material provided
for the testing represents a plant variety.
General remarks with regard to DUS testing
DUS testing is carried out in accordance with methodologies developed by the unit
responsible for this testing based on the UPOV guidelines. The UPOV guidelines for
DUS testing are edited by experts from various countries, who work in Technical Work
Groups (TWP) within the Technical Committee appointed by UPOV. The work of temporary
technical subgroups of the Technical Work Groups, concerning e.g. individual taxons or
unconventional testing methods, is also very helpful. Currently there are more than
200 guidelines for testing individual taxons.
Moreover, by providing information about the traits to be tested, these guidelines are
helpful to the person declaring a plant variety in order to gain exclusive right thereto.
The CPVO methodologies for the most important species have been developed based on
the UPOV guidelines. They are used in the EU Member States.
If no CPVO methodologies and UPOV guidelines exist for a taxon, the national
methodologies are used, which are developed taking into account the general
UPOV guidelines.
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This kind of procedure, the acceptance of general principles in relation to
organising/carrying out testing, and study-based comparison of those traits considered
important by all experts, makes it possible to harmonise the testing and to obtain comparable
results, and as a consequence facilitates international cooperation between the relevant
institutions carrying out DUS testing.
Methodologies for DUS testing comprise the following:
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technical advice;
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table of characteristics;
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explanations and testing methods;
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technical questionnaire (TQ).
In order for the plant variety to be protected, the following is required: distinctiveness,
uniformity and stability, confirmed on the basis of characteristics (traits) and their expression.
Definition of characteristics
Traits that are important for demonstrating distinctiveness (difference of one plant
variety from the others), and at the same time necessary for confirming uniformity and
stability, are stated in the methodologies. They may relate to morphology, physiology or to
the biochemical properties of plants. These traits must lend themselves to precise
identification and description. The expressions of characteristics are always described using a
scale. Traits with different degrees of expression, contained in the guidelines, enable DUS to
be confirmed and a plant variety to be described. In methodologies, where possible, there are
examples of plant varieties, which help to better ascertain the state of expression of a trait and
facilitate the interpretation of data.
The following traits are used in DUS testing:
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q u a l i t a t i v e – usually evaluated in a visual way. Their variation is not continuous and
the states of expression are categorically different. The states are marked by consecutive
numbers on an open scale, starting with 1, without limiting its scope, e.g. colour.
One of the types of qualitative traits is the so-called dichotomic characteristic, in which
there are two states of expression of a certain quality, e.g. presence of hair, waxy coating,
anthocyanine colouring (1 – none, 9 – present).
Another type of characteristic is so-called categorised data, which is present when each
of the observed specimens (e.g. a plant) is placed into one of the separate classes (categories).
By classifying all observed specimens, the so-called two-directional contingency table is
obtained. An example of such data would be the result of observing the flowering of grasses,
where a number of flowering plants is given for each compared plant variety in each of the
observation periods.
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p s e u d o q u a l i t a t i v e – measured or evaluated visually. The extent of their expression
is at least partially continuous, but varies in more than one dimension and cannot be
defined by simple description of two extreme expressions, e.g. shape.
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q u a n t i t a t i v e – measured or evaluated visually. Their changeability is constant
within the two border values. In order to describe a plant variety, the states of expression
of these traits are marked by the degrees of a 9-degree scale. The scale is constructed
starting with opposing expressions for weak or strong presence of the trait,
e.g. small/large, short/long, weak/strong (marked by degree on a 9-degree scale as 3 and
7).
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d e r i v a t i v e ( c a l c u l a t e d ) – being a product of the value of two or more
characteristics, e.g. the relation of length to width.
Usually, the qualitative traits (to a small degree) and the quantitative traits (to a greater
degree) may be subject to the impact of environmental conditions. In DUS testing, it is
preferable to have characteristics from both categories, which are less subject to this kind of
impact. If in a given case the trait is subject to environmental impact more than usual, it should
not be used.
Testing and evaluation of distinctiveness
The plant variety is considered to be distinct if it expressly differs from every other plant
variety, the existence of which is commonly known on the date of filing the application.
The difference between the plant varieties must be distinct and constant. In accordance
with the definition of a plant variety, it must relate to at least one characteristic. Testing of the
plant varieties propagated by vegetative means and self-pollinating is relatively easy, their
phenotype is characterised by the predominance of traits that are evaluated visually and
enable the grouping of plant varieties. When using these traits, even a one, two or threedegree difference in the scale can affirm the distinctiveness between plant varieties. This
depends on the size of variation of a given trait.
Cross-pollinating plant varieties represent a combination of genotypes, and their testing
is considerably harder. The number of traits useful for DUS purposes is limited here; most of
them are quantitative traits, requiring measuring and using statistical methods. There are few
traits eligible for grouping plant varieties and thus making it possible to narrow down the
collection. These are expensive studies, in many cases requiring sowing of the full collection
of plant varieties every year.
If the distinctiveness of a plant variety is established based on qualitative traits, as
above, the difference is considered to be significant if it is statistically proven with 1%
importance in the subsequent two testing seasons, or in two out of three testing seasons. In
some instances, there is a distinct difference in one direction (e.g. A>B) over two testing
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years, and in the opposite direction (A<B) in the other year. The conclusion from such an
observation suggests that there is no distinct and constant difference. Combining the results of
all three years of testing is more relevant in this case. Such procedure was expressed in the
COYD (Combined Over Year analysis for Distinctiveness) method recommended by UPOV.
It is based on the principle of analysing variance and interaction between plant varieties and
years. Using this approach, the effect of years is taken into account more than in the
previously used method.
The essential matter in testing the distinctiveness of mixed plant varieties is testing of
the lines used for their creation. To establish the distinctiveness of a mixed plant variety, it is
enough to confirm the distinctiveness of one of its components. The absence of line
(component) testing results may impede the issuing of an opinion on the distinctiveness of the
hybrid plant variety.
The basis of testing the distinctiveness of each plant variety is a collection of plant
varieties accepted for comparison, which is as wide as possible. To avoid erroneous decisions,
it must comprise all existing plant varieties. In some species, the collection comprises even a
few thousand plant varieties, both as descriptions in a computer database and as sample
specimens. It is estimated that testing and maintaining a collection absorbs 60-70% of
DUS testing costs. These costs can be reduced by grouping plant varieties in accordance with
distinctly differing characteristics. For this reason, it is very important for the breeder to
provide an appropriate and reliable description of the plant variety at the point of application,
stating the similar plant varieties. The declared plant variety will then be compared with the
others in the relevant group, thus considerably facilitating testing, apart from lowering the
costs. Providing the parent lines and formula in the case of a hybrid plant variety (the testing
office guarantees confidentiality) makes it possible to choose those comparison subjects that
are the most relevant in terms of their genetic relationship.
Cooperation between countries exists in order to reduce testing costs and to aim for the
highest quality of testing. Such cooperation has particular importance in the light of the
provisions of the latest Act of the UPOV Convention, which extends protection to all species.
Testing and evaluation of uniformity
Plant variety is considered uniform if it is sufficiently unified in its characteristics,
taking into account the variance resulting from a defined method of its propagation.
The plant variety is considered to be uniform if the changeability of its traits resulting
from hybrids, mutations and other reasons is as small as possible, taking into account the
method of breeding. It cannot cross a defined threshold, as accurate and reliable description of
the plant variety and evaluation of its distinctiveness then becomes impossible, whilst stability
of the traits is not guaranteed.
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Uniformity requirements are much greater for plant varieties propagated by vegetative
means, where all genetic information is passed on without changes from one generation to
another, as well as for self-pollinating plant varieties, which are highly homozygotic. For
these groups of plant varieties, the uniformity norms are precisely defined, giving a maximum
allowable number of atypical plants in a tested probe. For this purpose, mathematical
procedures are used, accepting a specified population standard and the degree of likelihood.
Cross-pollinating plant varieties have different genotypes and heterozygotic structures,
which leads to relatively high variance within a plant variety. In comparison with
self-pollinating plants and those propagated by vegetative means, the level of their uniformity
is lower and other methods are needed for estimating it. This uniformity is marked in relation
to the existing plant varieties. For measurable traits prevailing in this group of species (e.g. in
grasses), the criterion of uniformity used hitherto has been to compare the variance of the
tested plant variety with the average variance of all the plant varieties that make up the
collection, resulting from annual testing. Formulated in this way, the result of evaluating
uniformity of the tested plant variety may differ depending on the collection used for
reference. This criterion is currently replaced in the UPOV member states by a more
complicated COYU (Combined Over Years analysis of Uniformity) method, combining the
results of many years of testing and based on modifying the variance by the level of
expression of the analysed traits in the subsequent years. The uniformity of these types of
plant varieties ought to improve, together with increasing breeding activity in a given species.
The degree of uniformity of a hybrid plant variety depends on the number of its
components. A higher degree of uniformity should be expected in hybrid plant varieties
comprised of two components (in testing, these are regarded as essentially self-pollinating
plant varieties, where inbred lines may also appear) compared with plant varieties comprised
of three or four lines, where segregation of traits might occur. In these cases, the hybrid plant
variety may be interpreted as a cross-pollinating plant, i.e. its uniformity is evaluated in
comparison with documented hybrid plant varieties.
Testing and evaluation of stability
The plant variety is considered as stable, if its significant characteristics remain
unchanged following further propagations, and in the case of a particular propagation cycle,
at the end of each such cycle.
A stable plant variety keeps its characteristic traits (i.e. remains true to its description)
following subsequent propagations, or at the end of its relevant cycle of propagation. The
uniformity of the plant variety declared for testing, placed within the accepted limits, is
commonly acknowledged as a guarantee of the stability of traits. It is not possible, over the
course of two or three years of testing, to ascertain stability of traits with the same certainty as
in the case of distinctiveness or uniformity. This is even more the case, as a comparison with
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the next generation of seeds is necessary for such an evaluation. At the same time, the breeder
does not always provide relevant samples. Often, samples from the same lot of seeds are
compared over subsequent years of testing. Bearing this in mind, the majority of the
UPOV member states has in the main refrained from testing the stability of traits by
comparing generations. Such tests are carried out only in particular cases. The sample
received at the moment of declaring a plant variety must be accordingly uniform, since it
represents a sample specimen.
In subsequent years, varietal stability is tested in plant variety preservation control
studies, when sample specimens are renewed, and in studies on identity and varietal purity of
seed material lots.
New techniques
Intensive development of molecular techniques has provoked discussion on their
possible use in DUS testing and in the legal protection of plant varieties.
Discussion has been ongoing for many years in this regard in the UPOV forum of the
BMT Work Group, specially appointed for this reason, and in its work subgroups concerned
with sample species and the use of new techniques. A work subgroup concerning plants
propagated by vegetative means is likely to be created.
Currently, the following options are under consideration with regard to the use of
DNA testing factors in the testing of plant varieties:
Option 1: If the specific gene marker for the phenotype expression is available, then
it may be used in DUS testing, e.g., resistance to herbicides.
Option 2: If the border limits for molecular traits can be established in relation to
the minimum distances between expressions of traditional traits (phenotype), then
this option may be used.
This is used in assembling collections of plant varieties for testing.
Regarding a third option, no consensus was reached concerning the use of molecular
markers as new traits in the testing of plant varieties. The current view is that molecular
markers should not be used in DUS testing.
Further discussion is being facilitated by the BMT Work Group regarding the use of
new techniques in the identification of protected plant varieties.
Execution of exclusive right to the plant variety
The characteristics of a plant variety protected by exclusive right are described in detail,
in accordance with the DUS testing methodology in force.
In the case of infringement of the exclusive right to a protected plant variety, the
breeder may claim their rights based on the official description of their plant variety. Field
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testing is carried out for the resolution of disputes in order to compare plant material that is
the subject of the dispute with the plant material of the protected plant variety.
Observations and measurements of the traits in comparative tests confirm whether or
not the material provided for the investigation is identical to a sample of the protected plant
variety. In the best-case scenario, it is possible to carry out comparative tests in the same
place in which DUS testing was previously conducted.
The testing techniques discussed above, which may be used for the identification of
plant varieties, will accelerate the resolution of disputes and will allow for more effective
execution of the exclusive right to a plant variety by its owner.
Applications
The observed increase in the number of plant varieties declared for exclusive right
protection (often new species) requires the investigative workshop for DUS testing and
comparative tests to identify plant varieties to be constantly refined.
It is crucial to harmonise performance of the tests and techniques employed, so as to
enable unambiguous identification of plant varieties. This is a prerequisite for varietal
protection and execution of the right to their commercial use.
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