Abstract
(Englisch)
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Morphological character analysis and biogeographical studies are performed on wheat and wild related species in order to identify the potential production of spontaneous hybrids between wheat and wild species in nature. Herbarium sheets (pressed plants stored in scientific collections, collected 1850 up to recent years, Paris, Strasbourg, Montpellier, Lyon, Zurich, Geneva and Madrid, 1100 sheets from Switzerland, Southern France and Northern Spain) are analysed to gain an overview on long-term processes and rare events in nature from the following taxa: Cultivated crops (Triticum aestivum (wheat), Triticum monococcum) and their wild relatives (Aegilops cylindrica, Aegilops ovata, Aegilops speltoides , Aegilops squarrosa , Agropyron repens)
The aim of this study is to provide data on spontaneous hybridisation in regions of Southwest Europe for risk assessment of future transgenic wheat varieties. Hybridization events are for sure over-represented in the collections. With this end-of-the-pipe study, we analyse natural hybrids, often rare ones, which succeeded to grow to adult plants under the environmental conditions of the location.
Morphological character analysis
75 morphological characters defining wheat and its related wild species analysed in this study were chosen by combination of diverse identification keys of the floristic literature. For each species to be analysed, the anatomical descriptions were gathered organ per organ. From these synthetical descriptions, the organ description of wheat was compared with the one of each related species. Where a clear distinction was found, variables for the morphometrical character set were established. This analysis shows that inflorescence and flower characters are essential for species and hybrid identification.
The biometrical data are processed in a database and standardized for use in a statistical program (Principal Coordinate Analysis, PCO)
Hybrids between Aegilops ovata and Triticum aestivum were found as well as backcross plants with the wheat parent, called x Aegilotriticum speltaeforme (Jord).
Biogeography
Geographical distribution of the species is established taking into account the indications given by the regional floristic literature and by the herbarium sheets. Regions where we found hybrids in herbarium collections are indicated.
Conclusions
Hybridisation dynamics are medium in Southern Europe, due to the medium frequency of one of the relatives of wheat, Aegilops ovata, the gene flow dynamics needs to be considered in planning future field experiments transgenic wheat. On the other hand, agricultural reality shows, that the degree of autogamy is high in wheat and generally, gene flow in wheat can be managed, provided that some precautionary measures are carried through, such as keeping enough distance (ca. 20m) and controlling Aegilops ovata. The eventual hybrids are only rarely fertile, consequently the gene flow dynamics will be anyway very low.
All data of herbarium labels and morphometrical characters measured have been organized in a database for future development.
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