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António A. Montei>
António A. Monteiro1 & Timothy Lunn2
1. Introduction
Vegetable brassicas are an important and highly diversified group
of crops grown world-wide that belong mainly to the species Brassica
oleracea and B. campestris. In the western hemisphere,
including Europe, the predominance goes to B. oleracea,
a species that includes important crops such as cabbage, broccoli,
cauliflower, Brussels sprouts, etc. In Asia, B. campestris
is the most cultivated species owing to the great importance of
Chinese cabbage. Turnip and turnip greens, which also belong to
B. campestris, are cultivated world-wide but have much
less economic importance. B. juncea, that includes the
vegetables mustards, has some economic relevance in far eastern
countries but is a minor crop at the world level. B. napus
is probably the brassica receiving the most attention from breeders
at the world level, especially in Canada and France, but it is
only used for rapeseed oil. Therefore, it will not be considered
in this survey.
The centre of origin of B. oleracea is the Mediterranean
regof origin of B. oleracea is the Mediterranean
region. Vegetable brassicas are cultivated in Europe since very
ancient time from where they have spread to other parts of the
world (Nieuwhof, 1969). Brassicas include many different morphotypes,
are well adapted to temperate climates, require quite simple cultivation
techniques and produce abundant and nutritious food for man and
domestic animals. In the cold-winter regions of Europe white cabbage
is processed as sauerkraut, while in the mild-winter regions,
brassicas are the most important vegetable during the cool season.
In Korea, Chinese cabbage is used to prepare "kimchi",
the very popular national preserve.
The versatility of uses and the adaptability to growing systems
and man's life-style explain the importance brassicas have had
for centuries. However, the increasing consumption of salad vegetables,
the availability of a highly-diversified all year round offer
of imported and greenhouse grown vegetables make brassicas less
attractive for consumers in developed countries. Where world trade
tends to dominate the vegetable market, local availability is
no longer a comparative advantage for brassicas. However, vegetable
brassicas have new appeal in developed countries due to the potential
for market diversification of some new crop types, and to the
use of cauliflower and broccoli as salad crops. With an increasing
number of consumers aware of the importance of diet on humaners aware of the importance of diet on human health,
the potential benefits of a diet with green vegetables have given
brassica vegetables a better image during recent years. In less
developed countries brassicas are still considered as an important
source of cheap and abundant food.
Breeding strategy and targets are dependent on market trends.
Successful breeders anticipate changes in the market by developing
new varieties that are ready to be released to the growers when
their demand increases. It is therefore interesting to see how
breeding is reacting to eventual changes in brassica consumption
and to evaluate the potential influence that the brassica market
and growing systems may have on the definition of breeding targets
and priorities.
The objective of this paper is to analyse the present situation
and the perspectives of brassica breeding based on the authors
personal knowledge of the sector and on information collected
through an international survey of brassica breeders. The breeding
of F1 hybrid winter-cauliflower in Brittany is presented as an
example of successful co-operative breeding in tune with both
the demands of growers and the markets alike.
2. Survey on brassica breeding
2.1 Questionnaire
A questionnaire was mailed to 26 private and public brassica breeders
world-wide, in January, 1998. The questions included the number
of bre, in January, 1998. The questions included the number
of breeders per company/institution, the changes in the number
of breeders during the last ten years, the perspectives for brassica
breeding and its relative importance to other vegetable crops,
the relative distribution of breeding activity per crop, the ranking
of breeding objectives and the three major advantages/strengths
and threats/weaknesses for brassica breeding in the near future.
A total of 18 replies were received from 16 private and 2 public
breeders. Thirteen replies were from Europe, two from Japan and
one each from USA, India, and Korea.
2.2 Breeding activity
There is a total of 70 brassica breeders, outside Korea, working
for the companies/institutions questioned. The number of breeders
per company/institution varies from 1 to 12. In 60% of cases there
were less than five breeders per company/institution. Korea is
an exception with approximately 60 brassica breeders, from which
40 work in seed companies, 10 in research stations and 10 in universities.
This breeding activity reflects the enormous importance of brassica
crops in this country.
The number of breeders increased during the last ten years in
11 out of the 18 companies/institutions and has not changed in
7. Although, when the same group of persons were asked about the
future, 9 said that brassica breeding will increase, 8 replied
that it will not change and one said that it8 replied
that it will not change and one said that it will decrease. This
is a situation of moderate optimism. Brassica breeding is not
likely to decrease, rather it will remain stable or increase slightly.
Korea is again the exception. Breeding has been stable during
the past ten years and is likely to decrease in the future. This
is explained by the tendency for a decrease in the consumption
-currently extremely high- of brassicas due to dietary diversification,
and also to substitution of locally-bred varieties by imported
F1 hybrids.
2.3 Relative importance of brassica crops
The companies/institutions showed big differences in the pattern
of distribution of breeding activity between crops. The crops
deserving the most breeding attention vary considerably between
company/institution . There is a tendency for specialisation of
companies in a reduced number of crops. In 10 companies/institutions
over 70% of the breeding activity is concentrated in one or two
crops. In six companies/institutions one single crop may absorb
from 70 to 100% of the breeding activity. Some small breeders
become very specialised e.g. three breeders dedicate 80% of their
activity to cauliflower and one breeder 100% to kohlrabi. There
are still several less specialised companies/institutions where
the distribution of breeding activity is more equitable and tends
to follow the relative economic importance of the various crops.the relative economic importance of the various crops.
In Korea 60% of the brassica breeding is on Chinese cabbage.
Cauliflower is the most important crop attracting over 50% of
the breeding activity in 7 breeding companies/institutions (Table
1). Only two companies/institutions do not have cauliflower breeding.
Broccoli and white cabbage follow in decreasing order of importance.
Savoy cabbage and Brussels sprouts are much less important.
Table 1. Number of companies/institutions per class of percentage
of breeding activity dedicated to a certain crop
2.4 Breeding objectives
Breeding objectives can be addressed to satisfy the grower or
the consumer and be considered in terms of crop improvement
and product improvement. Such a division of objectives,
that may seem artificial since growers cannot survive by using
varieties that are not accepted by the market, can be used with
advantage for discussing breeding strategy and evolution. The
main criteria for crop improvement are yield, disease resistance
or abiotic stress, uniformity and continuity of cropping. Breeding
for appearance, commercial quality, shelf life, taste, and nutritional
value is part of product improvement.
The most important breeders objective in our survey is crop uniformity
which received 15 citations as high priority (Table 2). A uniform
brassica field makes grading much easier and reduces harvest time.
The final objective is to have a single-harveste.
The final objective is to have a single-harvested field of uniform
quality. High uniformity has been almost impossible to achieve
with open-pollinated varieties owing to the cross-pollination
habit of brassicas. The introduction of F1 hybrids, that can produce
a genetically-uniform population, has progressed slowly. Until
recently brassica hybrid breeding has been using the sporophytic
self-incompatibility mechanism since there is no cytoplasmic male
sterility in B. oleracea. The instability and complex
inheritance of the self-incompatibility mechanism makes its use
difficult and conducive to low quality F1 hybrids.
However, the production of brassica F1 hybrids is now developing
faster, albeit with some technical difficulties, using double-haploid
parent lines obtained through microspore culture and cytoplasmic
male sterility introduced from Raphanus sativus
into B. oleracea.
Table 2. Number of companies/institutions per class of importance
for each breeding objective
Disease resistance is also a very important breedease resistance is also a very important breeding objective
ranked as first priority by 13 out of 18 responders and not considered
a low priority by anyone. Pest resistance is much less important
since most responders considered it a medium or low priority (Table
2)
Sources of resistance to important diseases e.g. clubroot (Plasmodiophora
brassicae), black rot (Xanthomonas campestris pv.
campestris), fusarium yellows (Fusarium oxysporum
f. conglutinans) and downy mildew (Peronospora parasitica)
were identified (Chiang et al., 1993) but have not been
widely transferred into commercial varieties yet. The relative
delay of breeding for pest and disease resistance may be explained
by the low destructive effect of pathogens in brassicas and the
need to incorporate the resistant genes into a high number of
crop types. There is no disease that is a serious limitation to
brassica growing in large areas and the most destructive diseases,
for example clubroot, can either be controlled with chemicals
or kept below the threshold of economic damage with relevant growing
practices. The economic return of investment in breeding for disease
and pest resistance is quite low because it is dispersed among
too many different crop types, and resistant varieties are competing
directly with non-resistant ones that can still be used by the
growers without too much problem. The high interest inwithout too much problem. The high interest in and the
increasing present demand for breeding for pest and disease resistance
is related to a generalised interest in releasing "environmentally
friendly" varieties requiring a sparse use of chemicals.
Appearance, including colour and shape, is another important trait
(Table 2) and the only major breeding objective that is addressed
to the consumers. The rapid transformation of the vegetable market
with the improvement of packing and display facilities, the large
offer of commodities all the year round, and the increased presence
of colourful and appealing fruit and salad vegetables has forced
brassica producers to rise their presentation and quality standards.
Growers are looking for high commercial quality, including adequate
size and shape, good colour, firmness, and appearance to have
the produces easily accepted by the trade.
Crop yield, the traditional first priority for breeders, ranks
only fourth among breeding priority (Table 2), confirming the
high relative importance of qualitative traits in vegetable breeding.
Nutritional quality has as yet little importance since it was
ranked as medium or low priority by 17 out of 18 responders (Table
2). A similar low interest was shown by breeding for new crop
types. It is surprising to see that crop diversification and nutritional
quality, both of which are considered to be important marketing
advantages for the ed to be important marketing
advantages for the future, have received so little attention from
brassica breeders. Perhaps this is because crop diversification
has long been a breeding objective in brassicas (as well as in
other vegetable crops) without being accepted as such. The best
known example is broccoli which was introduced from Italy to the
rest of Europe and the United States and has now become one the
most important brassica crops world-wide. Chinese cabbage, due
to its increasing cultivation and consumption in western countries,
is also a good example of crop diversification. Lesser known brassicas
e.g. romanesco cauliflower, mustard greens or kohlrabi that could
also be interesting sources of crop diversification do not, as
yet, receive the same attention.
2.5 Advantages and weaknesses of brassica breeding
The responders were asked to cite the three most important strengths
and weaknesses of brassica breeding in the near future. Those
items mentioned by more than one responder are listed in Table
3. The answers were quite diverse, with little agreement about
the likely perspectives for vegetable brassica breeding. What
is considered an advantage for some breeders may be a threat for
others. This undoubtedly arises from the wide diversity of crops
and commercial situations concerned.
The potential advantages of the application of biotechnology to
brassica breeding received the largesttechnology to
brassica breeding received the largest agreement among responders
(Table 3). This is also true for vegetable breeding in general,
but in the case of vegetable brassicas is more prominent due to
the direct impact received from the huge research on Arabidopsis
thaliana and B. napus. Breeders working with B.
oleracea can have easy access to the knowledge on the use
of molecular markers, identification of genes for resistance,
transformation, etc. developed for A. thaliana and B.
napus.
There is no agreement on the impact of the market on brassica
breeding. Seven responders considered the market value and consumer
acceptance of brassicas as an advantage while 8 responders anticipate
adverse market perspectives owing to changes in consumer preferences.
The good market perspectives are related to the potential benefits
of brassicas for human health and the increased awareness of consumers
about the role of the diet on disease prevention. It may be expected
that in some more advanced markets the consumption of broccoli
and green vegetables will increase thanks to their role in protecting
against human cancer. Also, the good adaptability of brassicas
to a wide range of growing conditions could encourage their use
as a cheap source of abundant and nutritious food in developing
countries where brassicas are not traditional. However, it is
difficult to say if these market advantages can balcult to say if these market advantages can balance the overall
tendency for the decrease in consumption in developed countries
where brassicas tend to be replaced by the more appealing fruit
and salad vegetables.
The slow progress and difficulties of hybrid breeding pointed
out by five responders are related to the use of sporophytic incompatibility
for the production of F1 hybrids. However, the progress in the
use of cytoplasmic male sterility will make hybrid breeding much
easier in the near future.
A last comment on the concern of five responders about the impact
that the fusion policy and reduced profitability in the seed industry
may have on the number of brassica breeders. It is evident that
the concentration of seed companies will merge or cancel some
breeding programmes to reduce costs. Then there will be fewer
brassica breeders and the growers will be dependent on a narrower
genetic background.
Strengths and weaknesses of brassica breeding mentioned by
more than one responder *
Market value and consumer acceptance (7)
Increasing awareness of the high importance of brassicas in human diet (7)
Potential use of genetic divercas in human diet (7)
Potential use of genetic diversity (5)
Disease and pest resistance (3)
Adaptability to a wide range of growing conditions (3)
Crop yield (2)
Adverse market perspectives owing to changes in consumer preferences (9)
Fusion policy and reduced profitability in the seed industry (5)
Slow progress and difficulties of hybrid breeding (5)
Nutritional value and taste (4)
* The number of responders per item is presented
in brackets
3. Winter-cauliflower breeding in Brittany
Brittany is the leading region for vegetable crop production in
France with 25% of the national output and one of the most important
within Europe. Major regional crops include cauliflower, artichoke,
shallots and broccoli (80% of the national production for these
four). Field cropping of vegetables occupies some 70,000 ha, largely
in the north coastal area where good soils and a favourable maritime
climate allow year-round production.
The growers are organised into marketing co-operatives, themselves
co-ordinated through a regional body, the CERAFEL (Comité
Economique Agricole Régionale Fruits et Légumes
de Bretagne). This organisation of the market, going back some
30 years, coupled with the development of r going back some
30 years, coupled with the development of rapid transport links
has stimulated exportations to those countries of Europe where
production of vegetable crops in the winter months is impossible
for climatic reasons. Today, more than 50% of the area of brassica
crops is exported.
Financial support by the industry (via the CERAFEL) for scientific
and technical work has focused largely on the genetic improvement
of cauliflower, the region major vegetable crop. Strong links
have been forged with the INRA (Institut National de Recherche
Agronomique) and a veritable network of research and development
organisations has grown up across the region. There are currently
30 research and technical people directly involved in the vegetable
brassica breeding programmes at this moment.
One such organisation is the OBS, l'Organisation Bretonne de Sélection.
Established in 1970 through a joint initiative of the local grower
co-operative, the OBS has the particularity of being a wholly
grower-owned private company dedicated to crop improvement for
a vegetable producing region (admittedly one of Europe's largest).
In this sense, the company is a means to an end and plant breeding
just one aspect of an overall objective: total control of crop
quality. For winter cauliflower, the main objective is to provide
growers with a complete range of locally-adapted F1 hybrids and
, for this crop, 70% of the demand for seed within Brittany is
cu70% of the demand for seed within Brittany is
currently met by the OBS.
This can be considered something of a success story when one considers
that thirty years ago all of the cauliflower seed in the region
was farm-saved. The need to improve and homogenise the quality
of the crop was the deciding factor in the creation of the OBS
and the ties subsequently developed with INRA.
The identification and the multiplication of the best of the farm-saved
stocks was the initial task of the OBS. Varieties were maintained
and improved using mass selection with progeny testing, and with
seed production under polyethylene tunnels. These techniques allowed
a greater number of growers access to the better open pollinated
varieties, so contributing to the qualitative and quantitative
progression of the crop in the area.
The major drawbacks of this approach were an absence of control
over the breeding system and the difficulty of maintaining parental
clones from one generation to the next. With the emergence of
reliable tissue culture techniques in the early 1980's, this latter
obstacle was removed, so permitting a progression towards more
stable open-pollinated varieties of the "synthetic hybrid"
type.
In parallel to this improvement of open-pollinated material, hybrid
breeding programmes for both autumn and winter cauliflower were
started in 1970, jointly funded by INRA and the CERAFEL, with
scientific impute form y INRA and the CERAFEL, with
scientific impute form the INRA focused on the understanding and
the exploitation of the two breeding systems available in brassicas,
self-incompatibility and male sterility.
The main breeding criteria for cauliflower crop improvement (satisfaction
for the grower) are yield, uniformity and continuity of cropping.
The main criterion for product improvement (satisfaction of the
consumer) is curd quality: whiteness, structure, freedom from
disease and nutritional and sensorial value.
At OBS, breeding efforts are currently focused on providing F1
hybrids for the entire cropping calendar, but increasing consumer
awareness and concern for environmental issues has put disease
resistance/tolerance high on the scale of priorities.
Genotype x environment effects are great in these crops, and importance
is attached to the screening of prototype hybrids. Any hybrid
reaching the stage of large scale seed production at the OBS will
have been evaluated over at least 4 different years and on up
to 25 different sites across northern Brittany. The final stages
of evaluation include commercial-scale grower trials. All regionally-bred
material is compared to varieties available from other seed companies,
both on the regional experimental stations and on growers' holdings.
Given the considerable breeding effort in this crop, hybrid varieties
will inevitably replace the remaining open-pollinated populations
witlace the remaining open-pollinated populations
within the next five or so year.
Acknowledgements
The authors want to thank the helpful co-operation of the responders
to the questionnaire: Peter Crisp, Crisp Innovar Ltd, UK; S. Kennedy,
Elsoms Seeds Ltd, UK; A J M van der Nieuwenhuizen, Ryk Zwaan,
The Netherlands; Erling Hegelund, Dæhnfeldt, Denmark; S.
Jennings, A.L. Tozer Ltd, UK; C.M. Binnendijk, Enza Zaden B.V.,
The Netherlands; S.K. Tripathi, Mahyco Seeds, India; Remi Levieil,
Limagrain, France; P. Tjeertes, Novartis Seeds B.V., The Netherlands;
Hiromasa Noguchi, Sakata Research and Development Center, Japan;
A. Blom, Huizer Zaden Holland B.V., The Netherlands; Paul Degreef,
Sakata Seed Europe B.V., The Netherlands; M. Dickson, Cornell
University, USA; Jung-Myung Lee, Kyung Hee University, Korea;
Koji Sakamoto, Takii Plant Breeding & Exp. Station, Japan;
Nunhems Zaden B.V., The Netherlands; Frans van der Bosch, Royal
Sluis, The Netherlands; T. Lunn, OBS, France.
References
Chiang, M.S, C. Chong, B.S. Landry and R. Crête. Cabbage
in G.Kalloo and B.O.Bergh (eds.). Genetic Improvement
of Vegetable Crops. Pergamon Press, Oxford, 1993
Nieuwhof, M. Cole crops. Leonard Hill, London, 1969
© WCHR
1Instituto Superior de Agronomia, Technical
University of Lisbon, Tapada da Ajuda, 1300 Lisboa, Portugal
2Organization Bretonne de Sélection, 29250 Plougoulm,
France
Cauliflower Broccoli White cabbage Brussels sprouts Savoy cabbage
Uniformity Uniformity Disease resistance Appearance Crop yield Pest resistance Nutritional quality New crop types
Strengths Weaknesses
Wide application of biotechnology to brassica breeding e.g. double-haploidization, genetic transformation (11)
Slow progress on breeding for disease and pest resistance e.g. blackrot, clubroot (9)