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The centre of 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 "Kim chi", 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 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 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 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. 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

	Number of responders per class of importance
	High	Medium	Low
Uniformity	15	2	1
Disease resistance	13	5	0
Appearance	12	4	2
Crop yield	10		1
Pest resistance	3	9	6
Nutritional quality	1	9	8
New crop types	1	4	13

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-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

	Number of responders per class of importance
	High	Medium	Low
Uniformity	15	2	1
Disease resistance	13	5	0
Appearance	12	4	2
Crop yield	10	7	1
Pest resistance	3	9	6
Nutritional quality	1	9	8
New crop types	1	4	13

Disease 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 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 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 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 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 *

Strengths	Weaknesses
Wide application of biotechnology to brassica breeding e.g. double-haploidization, genetic transformation (11) Market value and consumer acceptance (7) Increasing awareness of the high importance of brassicas 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)	Slow progress on breeding for disease and pest resistance e.g. blackrot, clubroot (9) 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 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 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 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 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