Fungal bioactive molecules in interactions with plants and animals
von Ling Su
Datum der mündl. Prüfung:2019-10-15
Erschienen:2020-05-07
Betreuer:Prof. Dr. Petr Karlovsky
Gutachter:Prof. Dr. Petr Karlovsky
Gutachter:Prof. Dr. Ivo Feussner
Gutachter:Prof. Dr. Yuelin Zhang
Zum Verlinken/Zitieren:
http://dx.doi.org/10.53846/goediss-7963
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Name:Ling Su Ph.D dissertation _2020_May- SUB onl...pdf
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Zusammenfassung
Englisch
The ascomycete Verticillium longisporum is an allodiploid hybrid adapted to infecting crucifers. Hybridization of A1 with D1, D2 and D3 formed three V. longisporum lineages. Some Necrosis and Ethylene Inducing Peptide 1(Nep 1)-Like proteins (NLPs) are cytotoxic in dicot plants and some induce plant defense responses. Phytoalexins are plant defense metabolites induced by pathogen infection that are toxic to microorganisms. We found that the genome of V. longisporum harbors 8 NLP genes which are similar to NLP genes of V. dahliae. The purified product of VlNLP1 was cytotoxic in Arabidopsis, Brassica napus, and Nicotiana tabacum and triggered an immune response in Arabidopsis. The expression pattern of NLP genes varied among the lineages of V. longisporum and among strains within a lineage. VlNLP3 was the only VlNLP gene, the expression of which was not detectable in the virulent strain VL43. However, infection of B. napus with VlNLP3 overexpression strain was indistinguishable from the infection with the wild type strain, showing that silencing VlNLP3 was not necessary for the adaptation of V. longisporum to B. napus. No correlation between the expression patterns of NLPs and strain aggressiveness was found. Predation by the nematode Aphelenchoides saprophilus or springtail Folsomia candida has not affected the expression of eight NLP genes in V. verticillium nor three NLP genes in Fusarium graminearum. The springtail F. candida has not distinguished between the wild type strain of Zymoseptoria tritici and a mutant with the only NLP gene disrupted in food choice experiments. Feeding F. candida on the Z. tritici strain with the disrupted NLP gene has not enhanced the fitness of the springtail as compared to feeding on the wild type strains accumulating NLP. We also describe the induction of brassilexin, spirobrassinin, rutalexin, and cyclobrassinin in oilseed rape plants by V. longisporum infection, and the ability of Verticillium species to detoxify these phytoalexins. Brassilexin at a concentration of 20 µg/ml completely inhibited the germination of V. longisporum spores; brassinin and cyclobrassinin have not inhibited spore germination. None of the three phytoalexins at a concentration of 40 µg/ml inhibited the growth of V. longisporum. This study shows that NLPs of V. longisporum play none or marginal role in the infection of B. napus, and also indicate that NLPs of V. longisporum, F. graminearum and Z. tritici are not involved in defense against animal predation. The role of NLP-family is still unclear. These results can be interpreted as an encouragement that research on NLPs biological role should not be restricted to plant disease alone.
Keywords: Verticillium longisporum; Necrosis and Ethylene Inducing Peptide 1(Nep 1)-Like proteins (NLPs); Defence against predators; Phytoalexins