Untersuchungen zu potentiellen ökologischen Effekten von gentechnisch vermittelter Nematodenresistenz auf pflanzengenetische Ressourcen am Beispiel der Zuckerrüben-Wildform (Beta vulgaris ssp. maritima)

Hybridization within or across different species in the genus Beta has been widely used for breeding of sugar beet (Beta vulgaris ssp. vulgaris). Interbreeding is easy with sea beet (Beta vulgaris ssp. maritima). The genetic similarity of the sea beet provide a useful source of genetic characters, which could then be transferred to cultivated varieties. More complicated are inter-species crosses with Beta procumbens, but a nematode resistant gene was recently transferred with modern non-GMO as well as GMO breeding methods. However, new genes with a potential impact on fitness characters have entered the Beta vulgaris species gene pool, and natural gene flow and introgression from cultivated sugar beet to wild sea beet plants may have important consequences. Cultivated beet seed production areas are sometimes adjacent to sea beet populations. It is likely that new transgenic or non-transgenic cultivars of sugar beet may hybridize with wild beets in the seed-production areas (f.e. nothern Italy). In this study I used experiments to study the potential ecological role of genes mediating resistance to an important beet pest, the nematode (Heterodera schachtii). This nematode causes a root disease, which decreases sugar quality. The gene of interest (Hs1pro-1) is widespread in Beta procumbens but so far unknown in (Beta vulgaris ssp. maritima). Theoretically, B. maritima should be susceptible to H. schachtii since interbreeding has not provided any source of resistance to cultivated beet. But the potential co-existence of this nematode species with wild B. maritima along seashores has not been studied systematically. Detecting H. schachtii in natural habitats of B. maritima is difficult to perform. I therefore measured the susceptibility of different B. maritima populations under controlled nematode infestation in the laboratory at soil conditions found in natural seashore habitats. These habitats are characterized by moderate to high salt levels in the soil solution. If the fitness of nematodes is negatively effected by high salt conditions, than nematode resistance genes are of minor importance for wild B. maritima seashore populations. Our first results show that B. maritima are susceptible to H. schachtii even under high salt conditions, but exhibit weaker symptoms than cultivated beet. These preliminary results suggest that nematode resistance genes may have a moderate impact on the fitness of B. maritima, if H. schachtii is widespread in natural habits