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Regulatory Aspects of Breeding
for Field Resistance in Crops
By
Niels P. Louwaars
  
Keywords:  Policies/Programmes; Intellectual property rights; Disease/pest resistance; Seed; Socio-economic impact. 
Correct citation: Louwaars, N.P. (1997), "Regulatory Aspects of Breeding for Field Resistance in Crops." Biotechnology and Development Monitor, No. 33, p. 6­8. 

The regulatory frameworks for varietal approval and quality seed control concentrate on governing the seed supply. They do not intend to influence the direction of plant breeding. However, the indirect result of the variety release system is that breeders target high input levels, wide adaptation, and easily recognizable traits. In the extreme case, the main objective of the breeder is not to develop varieties for the farmers but to develop varieties that can be approved by the variety release committee. This often results in approved seeds that have little significance to farmers.

In most countries in the South, formal seed production has developed as part of the Green Revolution strategy of agricultural development. Plant breeding would increase yield potential under optimum growing conditions, seed production would be a necessary vehicle for technology transfer, and the seed and inputs would be subsidized. The centralized seed production infrastructure has been built to resemble the successful European and North American seed industries.
Similar to the development of formal seed production, seed laws in the South are strongly based on European or US seed laws. Such laws regulate variety release and official seed certification, and they establish the institutional framework of national seed councils and certification agencies. More recently, plant variety protection (PVP) has been introduced in the regulatory system. A major difference with the European systems is that the variety release and seed certification in Europe was originally based on a farmers' wish to regulate seed supply. Hence, farmers' organizations have a strong voice in the system. For example, farmers are represented in the Netherlands' seed certification foundation. Whereas in the South, such seed regulations were fitted in the existing bureaucratic structures. The seed quality control institutions became the driving force behind the development of seed legislation. They need legal backing when conflicts arise with seed producers.

Variety release systems
Variety release may become a goal in itself when regulatory systems are too rigid. Release is the yardstick on which the effectiveness of public plant breeding is measured. Their reward system is commonly based on the number of varieties released, not on the widespread use by farmers. Hence, the objectives of plant breeding are likely to be adapted to the variety release procedure.
A variety release system generally involves the following procedure: (a) application with a formal variety release committee and variety registration, including a variety description; (b) testing for the value for cultivation and use (VCU) of the variety involves different sites over a number of seasons; and (c) testing for distinctness, uniformity and stability (DUS). The test results are analyzed by the committee either to approve or reject for formal release. In all these stages there can be a bias towards favouring particular types of varieties. Since variety release is basically geared to supply varieties to the formal seed sector, strict uniformity standards of seed certification have to be acknowledged. Uniformity can be tested before a variety enters the trials, or parallel to this.
The management of variety testing makes it doubtful whether the trial results have any value to most farmers. Breeding is still expected to target favourable agro­ecological conditions for a monoculture of crops that are high yielding and have wide adaptations. Below are some of the management problems:

On­farm variety trials are becoming increasingly popular with variety release systems. This positive development however, hardly ever contributes to releasing more adapted varieties because such on­farm trials are often completely researcher­managed and thus similar to station trials. Often the results cannot be easily analyzed statistically, the non­numerical comments by farmers are especially difficult to include in reports. Resistance breeding
During the Green Revolution, plant breeding for resistance to pests and diseases has long been regarded as secondary to breeding for yield. Today, resistances are a major, if not the most important, focus of plant breeders worldwide. The different strategies to obtain resistance to a disease are as follows: Other strategies include variety management, such as rotation in space and time. In the first two cases the selection pressure is reduced through the 'peaceful co­existence' of the pathogen and the crop, called field resistance. All these strategies are much more complex than the gene­for­gene strategy of vertical resistance and thus much more difficult to build into breeding programmes for modern agriculture. Manipulation of polygenic traits such as transferring a desired level of resistance to a new generation of varieties is extremely complex. This involves a good knowledge of the development patterns of the pathogen and its interactions with the host. Partial resistance can, for example, be based on a delay of infection or reduced spore formation.

Releasing resistant varieties
The variety release systems tend to discriminate certain resistance strategies such as horizontal resistance and multiline varieties. On the other hand, the result of breeding for vertical resistance is a uniform variety that can be easily observed and is likely to be released. Breeding for horizontal resistance can also result in conventional uniform variety, which could pass a standard variety release procedure without many problems. Complications may arise however, when the testing facilities are poorly equipped or poorly staffed since varieties with partial resistance to a particular pathogen do carry symptoms of the disease. Their value lies in the reduced damage due to a slowing down of the epidemic when planted in large fields. Because they do carry symptoms they are likely to be recorded as susceptible and consequently rejected. Partially resistant varieties may not be identified in standard variety trials.
The problem with multiline varieties is that they show field resistance which is comparable to partial resistance. In addition, they are less uniform than conventional pure­line varieties. Especially where registration is based on the requirements for plant variety protection, multilines are often rejected. When multiline varieties have to be released individually, they may fail because they will not have better yields compared to all other varieties.
Finally, different registered varieties could be blended and sold to farmers. Such varietal mixtures could be constituted by seed producers or seed merchants, and if chosen carefully, could buffer disease epidemics. Most certification regulations, including those in some European countries, do not allow blended seed on the market. Control would be extremely difficult, but ruling out a potentially useful disease management strategy by law does not seem useful either.

Multiline wheat in the Netherlands
An illustrative case is a multiline wheat variety bred by the Netherlands' seed company Zelder in the late 1970s. This novelty put pressure on the Netherlands' variety release system. The variety, aptly named 'Tumult' (Dutch for 'commotion'), was insufficiently uniform, and thereby could not be released. The final option was to register the constituting lines as separate varieties. These are hardly distinctive because they are different only for the resistance gene. Moreover, testing of the lines individually for VCU would cause problems. The resistance to yellow rust of individual lines was below standard, but when tested as a multiline the variety was superior. Eventually, the registration authority was convinced by the breeder to test and approve the multiline variety as one entity. However, commercially it turned out to be a failure. The breeding and release procedure caused the multiline variety to be outdated before it even appeared on the market. Additionally, maintaining the lines and producing the seed separately was too expensive. The Zelder seed company has not produced multiline varieties since then.

Regulations as impediments
Even though breeding for vertical resistance is the easiest option, experience shows that this strategy bears some important risks. A resistance can be broken by the pathogen, causing massive losses. Such losses are more disastrous for risk­prone, small­scale farmers in low external input farming conditions, compared to their more commercial colleagues. The seed replacement rate in commercial farming is high. When a resistance is broken, farmers can purchase seeds of a new variety the next season if the breeders have done their job in being 'ahead of nature'. Their loss has to be absorbed for one or two years only, which can be done in the presence of effective rural credit. This was the case of the massive destruction of maize due to blight in the early 1970s in the USA.
Breeders for low external input farmers, who are mostly in the public sector, have different responsibilities. Their clients obtain seeds to a large extent through the local seed exchange mechanisms and variety replacement is slow. In the absence of effective rural credit schemes and commercial seed supply systems, a serious outbreak of a disease cannot be tackled by the market. Durability of resistances to diseases is therefore even more important in such systems. Breeding for polygenic resistance or multilines should be promoted, even though the methodologies are more complex. This is currently discouraged due to very ineffective variety release systems.
The importance of such regulatory frameworks in the breeding strategies has been acknowledged only very recently. Regulations are an impediment to novel approaches, such as breeding for specific adaptation and participatory plant breeding which are very valuable tools for targeting less endowed farmers.
Niels P. Louwaars

Centre for Plant Breeding and Reproduction Research (CPRO­DLO), P.O.Box 16, 6700 AA Wageningen, the Netherlands  Fax (+31) 317 418 094; E­mail n.p.louwaars@cpro.dlo.nl

Sources
S. Ceccarelli (1989), "Wide adaptation: How wide?" Euphytica 40, 197­205.

N.P. Louwaars and G.A.M. van Marrewijk (1996), Seed Supply Systems in Developing Countries. Wageningen, the Netherlands: CTA.

R. Tripp (1997), New Seeds and Old Laws. London, UK: Intermediate Technology Publications.

D.S. Virk, A.J. Packwood and J.R. Witcombe (1996), Varietal Testing and Popularisation and Research Linkages. Discussion papers series. Bangor, India: Centre for Arid Zone Studies.



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