Tomato fruits can be contaminated by saprophytic strains of Alternaria alternata which is the reason for the frequent occurrence of Alternaria toxins like alternariol, alternariol monomethylether or tenuazonic acid in these types of products. It was shown earlier that alternariol is a colonization factor for tomatoes. In the current analysis two different tomato genotypes were analysed by untargeted comprehensive twodimensional gas chromatography mass spectrometry (GC×GC-MS). This analysis revealed clear differences in the metabolic profiles which were paralleled by differences in resistance towards Alternaria colonization. One of the genotypes was more resistant against A. alternata infection and contained high amounts of chlorogenic acid in contrast to the other genotype which was sensitive against infection. In in vitro analysis, chlorogenic acid reduced alternariol biosynthesis during the first days of growth of A. alternata. Expression analysis of the alternariol polyketide synthase gene, a key gene in the biosynthesis of alternariol, also revealed a temporal reduction in its expression in the first phases of growth. However by chromatographic analysis it could be demonstrated that chlorogenic acid was degraded over time. This degradation leads to a relief of inhibition resulting in an only temporal inhibition of alternariol biosynthesis. In vivo colonization experiments revealed that chlorogenic acid reduces colonization of tomatoes by A. alternata in a concentration dependent manner, which however is partly counteracted by the addition of alterariol.

The laws to secure intellectual property rights on plant germplasm have been strongly developed in parallel to the ongoing seed market consolidation. Germplasm as a commons, i.e., a natural resource accessible to all members of a society, receives almost no legal protection. On the other hand, the use of germplasm and released cultivars in breeding is increasingly restricted by intellectual property rights. In this study, approaches to open source plant germplasm are discussed, and the Open Source Seed (OSS) Licence is introduced and analysed. The OSS Licence was developed by an interdisciplinary working group of plant breeders, agricultural scientists, lawyers, and commons experts in Europe. The aim is to protect germplasm as a commons, support the free exchange of germplasm, stimulate plant breeding, reduce costs, and accelerate innovation. The OSS Licence is a legal tool and novel approach that extends its reach on derivatives of licenced germplasm. It is compatible with current seed laws. Effects on the access to plant germplasm, on breeding for diverse pedoclimatic environments, socioeconomic systems, and on biodiversity as a whole can first show after a few breeding cycles. The impact of open source germplasm on these aspects needs to be monitored carefully.

On‐farm management of landraces or older cultivars of crop plants is often recommended to combine conservation and use of genetic resources, but experimental studies on on‐farm management are hard to find, particularly in industrialized countries. To investigate whether on‐farm management results in regional adaptation and enhances crop biodiversity, an experiment with lentils (Lens culinaris Medik.) was designed. Lentil production has almost ceased to exist in central Europe, but lentils may still be found in gene banks and have remained a popular food. Three landraces were evaluated on three farms in Germany; at each farm, three populations evolved, based on three selection methods: (i) natural selection, (ii) visual mass selection, and (iii) selection for yield of single plant progenies. These selection methods were applied for two to four years. The nine populations developed for each landrace (three methods × three locations) were grown in a comparative trial on two of the farms. In most cases, populations selected at a specific location were at this location superior in yield to populations selected at other locations, indicating that on‐farm management can result in site‐specific adaptation. Significant changes in morphological and phenological traits occurred. For one landrace, natural selection increased seed weight. The response to different selection methods largely depended on landrace and selection site, and no method was generally superior. In conclusion, on‐farm management is a useful approach to maintain, use, and develop plant genetic resources. Natural selection as the most cost‐efficient method is recommended.

The tomato is the most important vegetable globally. In England, outdoor tomatoes are widely grown by amateur gardeners, with the number of their allotment plots exceeding 150000. For instance, in Germany, only about 16% of tomato plants are cultivated according to organic standards, although these rates are expected to increase. Breeding for yield and fruit quality can increase resource efficiency. Therefore, we need to evaluate the variability of yield and fruit quality parameters, to calculate the heritability of these traits and to identify superior genotypes for organic outdoor tomato production and breeding. With these aims, we grew 24 tomato genotypes of diverse origins in a two-year field trial. The heritability of quality traits such as glucose, fructose, organic acid, and lycopene was high. The medium heritability for yield suggests that trials with a larger number of locations are needed for the reliable selection of this character. Negative correlations of sugar concentrations with fruit weight and of organic acid concentration with fruit weight and yield suggest trade-offs in breeding for larger fruits and higher yields. Breeding for increased lycopene content is not subject to these challenges; the concentrations of the primary metabolite sugars and organic acids are positively correlated.

Knowledge about the degree of outcrossing is essential for on farm crop management and breeding schemes and for lentil (Lens esculenta Medik.) only restricted evidence was available. Three varieties were investigated in two central European locations to foster research into on farm maintenance and development of cultivars. To determine outcrossing rates, the complete dominance of Ôorange cotyledonsÕ over Ôyellow cotyledonsÕ was used as a marker. The degree of outcrossing ranged from 0.06% to 5.12%. Results were strongly influenced by cultivar, year and location. The outcrossing rate of individuals also varied within cultivars, the extremes being 0% and 22.2%. There is evidence that the degree of outcrossing can be heritable. The potential for evolutionary changes in lentil cultivars can be considerable. Growing cultivars close together or as a mixture can lead to natural or even conscious selection and local adaptation. On the other hand, spatial separation may be necessary to avoid undesirable cross-pollination.