Early stages of pathogenesis in plant pathogenic fungi
Final Report Abstract
Detailed knowledge about the molecular processes involved in early plant-pathogen interactions are crucial for the development of effective disease control strategies. In this trilateral research project including partners from Palestine (Hebron University), Israel (TAU) and Germany (WWU Münster) we studied in detail the interaction of the grey mold fungus Botrytis cinerea, which causes heavy economic losses also in the Middle east, especially in green house cultures, with his host plants, mainly the model plant bean. We had shown before that several conserved fungal signaling cascades are involved in these early processes, including spore formation, germination, and host cell penetration. During this final project period we focused on the following aspects: In a broad microscopic and plant test assay (HU) we studied the impact of various parameters on spore germination, germ tube development, penetration and lesion development. We could show e.g. that Ca level and different nitrogen sources have high impact on these parameters. We tested also the impact of mutations (generated by WWU) in various signaling or enzymatic components (small GTPases and their partners; Ca transporters, enzymes involved in nitrogen metabolism) on these parameters. In a detailed molecular approach (TAU,WWU) we could show that small GTPAses like BcRac and BcCdc42 have strong impact on the early stages; this analyses included also downstream partners like the GEF BcCdc245, the PAKs BcCla4 and BcSte20, in addition, the role of the stress-activated MAPknase BcSak1 was analysed in detail; it is essential for penetration. Although only partially related to the project, we showed that early pathogenic event induce PCD in Botrytis and that anti-PCD machinery is essential for successful manifestation of early stage and establishment of the infection. These findings highlight the importance of the early stages for disease and mark this stage as critical for disease progression, and hence as a prime target for disease management approaches. In a genome wide expression analysis (arrays) and a parallel proteomics approach we identified sets of early expressed genes, including potential effectors and transcription factors. We initiated a functional analysis of candidate genes, but because of the obvious redundancy of the system we could so far not identify single essential genes.
Publications
- (2011) Regulation of pathogenic spore germination by CgRac1 in the fungal plant pathogen Colletotrichum gloeosporioides. Eukaryotic Cell 10: 1122-1130
Nesher I, Minz A, Kokkelink L, Tudzynski P, Sharon A
- (2011) The Botrytis cinerea REG1 protein, a putative transcriptional regulator, is required for pathogenicity, conidiogenesis and for the production of secondary metabolites. MPMI 24: 1074-1085
Michielse CB, Becker M, Heller J, Moraga JR, Collado IG, Tudzynski P
- (2011) The small GTPase BcCdc42 effects nuclear division, germination and virulence of the grey mould fungus Botrytis cinerea. Fungal Genet. Biol. 48: 1012-1019
Kokkelink L, Minz A, Al-Masri M, Giesbert S, Barakat R, Sharon A, Tudzynski P
- (2012) The MAPK BcSak1 of Botrytis cinerea is required for pathogenic development and has broad regulatory functions beyond stress response. MPMI, 25: 802-816
Heller J, Ruhnke N, Espino J, Massaroli M, Collado I, Tudzynski P
- (2013) Involvement of Botrytis cinerea small GTPases BcRAS1 and BcRAC in differentiation, virulence and the cell cycle. Eukaryotic Cell 12: 1609-1618
Minz Dub A, Kokkelink L, Tudzynski B, Tudzynski P, Sharon A
(See online at https://doi.org/10.1128/EC.00160-13) - (2014) Functional analysis of BcBem1 and its interaction partners in Botrytis cinerea: impact on differentiation and virulence. PLOS One 9(5): e95172
Giesbert S, Siegmund U, Schumacher J, Kokkelink L, Tudzynski P
(See online at https://doi.org/10.1371/journal.pone.0095172)
