Untersuchungen zur Variabilität morphologischer Eigenschaften und volatiler organischer Verbindungen von Petersilie (<em>Petroselinum crispum</em> [Mill.] Nyman) in Bezug zu Wirt-Parasit- Interaktionen ökonomisch bedeutender Pathogene...

...sowie Marker-Merkmal-Assoziationen

Abstract

With the present work valuable results were generated by variability studies within a world collection of 219 parsley origins based on a high phenotypic and genetic diversity. For the first time with this range of accessions, the pathogens S. petroselini and P. petroselini showed distributions of attack which pointed to a quantitative or qualitative characteristic of resistance. Moreover, S. petroselini and P. petroselini showed infestation patterns which exhibited significant relations. Genotypes with a non-woody or a thickened napiform root showed higher levels of the VOCs (E)2-hexenal, hexanal, (ß)-myrcene and dimethylstyrene. Accessions weakly infested by S. petroselini or P. petroselini had higher contents of (E)2-hexenal, (ß)-myrcene, hexanal, dimethylstyrene and the unidentified substance a40, which suggests correlations of these compounds with the defense reactions against the two pathogens. A distance analysis on the basis of 205 molecular markers has led to the division of the collection into two clusters. The stages for the characteristics curling of leaf, thickening and lignification of root divided almost entirely between the two molecular distance clusters according to the infraspecific taxa var. crispum and var. tuberosum. Among the accessions of
the molecular distance clusters, considerable differences in the host-parasite interactions of S. petroselini and P. petroselini were recorded. The VOCs (E)2-hexenal, (ß)-myrcene, hexanal, dimethylstyrene and the substance a40, which already had higher levels in genotypes with lower levels of infestation by S. petroselini and P. petroselini or with typical properties for root parsley, were also moderately to strongly related to the molecular distance clusters. A principal component analysis based on 42 VOCs led to two clusters which were almost identical with the molecular distance clusters as regards accessions. A study for population structure resulted in two subgroups having the same composition of accessions as the two molecular distance clusters. In an association study of the characteristics curling of leaf, thickening and lignification of root, and the host-parasite interactions of S. petroselini and P. petroselini and 16 VOCs, representative molecular marker candidates were found. Some of these marker-trait associations are interesting enough to be verified in further analyses or to be refined with other molecular techniques. A selection of landrace accessions enabled the integration of the regional provenance of the genotypes for the evaluations. Accessions from North Africa and the Balkans agglomerated in the molecular cluster two. However, genotypes from the Near and Middle East or adjacent regions and Western Europe were found mainly in the molecular cluster one. Accessions from the Balkan region were significantly less infested by S. petroselini and P. petroselini. Values of  significantly stronger infestation by S. petroselini and P. petroselini, however, were shown by genotypes from the Near and Middle East or adjacent areas. The search for sources of resistance to S. petroselini in parsley has led to promising accessions, which could be increased for resistance via selection. The review of the occurrence of resistance to S. petroselini confirmed quantitative properties. Based on the world collection of parsley, relations mainly of hexanal, (E)2-hexenal, (ß)-myrcene and dimethylstyrene to resistance to S. petroselini are to be found on a similar level, partially closer, also in other field trials for resistance to S. petroselini and thus a combination of these VOCs with the defense against S. petroselini in selected genotypes is conceivable. Furthermore, an effective methodology for the crossing of parsley had been developed, which achieved high rates of success depending on the parents to combine. Under the given experimental conditions, with the plant material used, host-parasite interactions which correspond to a monogenic dominant inheritance of resistance were found in climate chamber experiments on resistance to S. petroselini. The present study showed promising results which provide a basis for continuing research or utilization in plant breeding and, finally, for an increase of efficiency and quality in parsley cultivation, along with environmental conservation by reducing the need for applying fungicides.