Marker-assisted optimization of an expert-based strategy for the acquisition of modern lettuce varieties to improve a genebank collection

To regularly improve the composition of the lettuce collection of the Centre for Genetic Resources, the Netherlands (CGN) with modern varieties, feedback from crop experts is used to select approximately 10% of the new material for incorporation in the collection. In the present study, assessments of six experts were compared to microsatellite data of 414 new varieties and 1408 existing accessions. Based on the microsatellite data, the extent to which the genetic diversity of the collection would be enriched (added value) was calculated for specific sets of new varieties. When individual assessments of experts were evaluated, the total added value of expert-based selections was not significantly higher compared to randomly chosen groups, except for a single expert. Unfamiliarity with new varieties was shown to be a crucial factor in the assessment of crop experts. According to the current acquisition protocol that seeks for consensus among experts, varieties are selected based on recommendations from at least three experts. This protocol also did not perform better than randomly chosen groups of new varieties. However, significantly better results were obtained with alternative protocols. It was concluded that breeding value was a more decisive criterion in the current acquisition protocol than maximal extension of the genetic diversity within the collection. A modified protocol addressing both commercial and diversity aspects was suggested in order to meet the demands of plant breeders as well as conservationist

Outcrossing and coexistence of genetically modified with (genetically) unmodified crops: a case study of the situation in the Netherlands

With the introduction of genetically modified (GM) crops the EU has demanded that individual member states enact measures to prevent inadvertent admixture – through outcrossing – of genetically modified organisms (GMOs) with products from conventional and organic farming. A literature review on outcrossing was prepared for the Coexistence Committee installed in the Netherlands in 2004. For sugar beet and potato, isolation distances do not appear to be of overriding importance, as true seeds are not part of the harvested product. The only route for admixture is through persistence of GM hybrid volunteers, and these should already be subject to strict control in good agricultural practice. Data on maize indicate that a distance larger than 25 m is needed to keep admixture below the EU labelling threshold of 0.9%, and larger than 250 m to remain below the 0.1% threshold as favoured by organic farming organizations. Oilseed rape is more complex because apart from pollen flow also persistence of volunteers in and outside arable fields, and hybridization with wild relatives play a role. At the present state of knowledge, isolation distances of 100–200 m and rotation intervals of 6–8 years might be warranted for the 0.9% threshold. It is as yet not clear whether a threshold of 0.1% is achievable in practice. The conclusions are compared with the measures recommended by the Dutch Coexistence Committee

Benefits and costs of biologically contained genetically modified tomatoes and eggplants in Italy and Spain

In this paper we assess the benefits and costs of introducing biologically contained genetically modified (GM) crops, with an application to the potential introduction of GM tomatoes and eggplants in Italy and Spain. Such crops possess both the standard beneficial GM traits, and they prevent introgression of transgenes from GM crops to their conventional or wild relatives, thereby adding to the safety of their cultivation. As a result, coexistence regulations for these crops are less stringent than for crops without biological containment. The potential adoption of biologically contained GM tomatoes and eggplants is assessed in a cost-benefit framework for Italy and Spain. We conclude that biological containment has considerable potential benefits if policy makers are willing to loosen the restrictions on the introduction of these varietie

Distribution of genetic diversity in wild European populations of prickly lettuce (Lactuca serriola): implications for plant genetic resources management

Genetic variation in Lactuca serriola, the closest wild relative of cultivated lettuce, was studied across Europe from the Czech Republic to the United Kingdom, using three molecular marker systems, simple sequence repeat (SSR, microsatellites), AFLP and nucleotide-binding site (NBS) profiling. The ‘functional’ marker system NBS profiling, targeting disease resistance genes of the NBS/LRR family, did not show marked differences in genetic diversity parameters to the other systems. The autogamy of the species resulted in low observed heterozygosity and high population differentiation. Intra-population variation ranged from complete homogeneity to nearly complete heterogeneity. The highest genetic diversity was found in central Europe. The SSR results were compared to SSR variation screened earlier in the lettuce collection of the Centre for Genetic Resources, the Netherlands (CGN). In the UK, practically only a single SSR genotype was found. This genotype together with a few other common SSR genotypes comprised a large part of the plants sampled on the continent. Among the ten most frequent SSR genotypes observed, eight were already present in the CGN collection. Overall, the CGN collection appears to already have a fair representation of genetic variation from NW Europe. The results are discussed in relation to sampling strategies for improving genebank collections of crop wild relatives

Crop volunteers and climate change; Effects of future climate change on the occurrence of maize, sugar beet and potato volunteers in the Netherlands

COGEM has commissioned a research project on the effect of the possible future climate change on the occurrence of volunteers. One of the aspects that is considered in the risk assessment of GM crops is whether this crop is able to survive and/or establish in the Netherlands. Climate change could possibly facilitate the survival of a conventional or GM crop. This research project was carried out to investigate whether the survival of maize, potato and sugar beet could change as a result of future climate change in order to allow a timely adjustment of COGEM’s advices if needed

Inventory of observed unexpected environmental effects of genetically modified crops

In general, it can be concluded that very few clearly unexpected effects were observed during the large scale post-release growing of herbicide-tolerant crops and Bt crops. Of course, one has to keep in mind Applied Plant Research (Praktijkonderzoek Plant & Omgeving ) 14 that there will always be an element of subjectivity in assessing effects as “unexpected”. Furthermore, it is also possible that certain effects are becoming visible only after a longer period than 10 – 15 years, but no indications for such effects were found in the literature. Besides the reports about the Farm Scale Evaluations no other reports were found with information about effects of GM crops on biodiversity in ecosysystems surrounding the production fields. Unexpected effects caused directly by the genetic modification were not found. Only in herbicide-tolerant crops, we concluded to some indirect unexpected effects: the reduced uptake of micro-nutrients and some positive and negative effects on susceptibility to diseases. These effects were specific to herbicide use with glyphosate-tolerant crops. Based on this, it was not possible to draw general conclusions for developing protocols for post-release monitoring of environmental effect