Characterization of genes coding for small hypervariable peptides in Globodera rostochiensis

摘要: Plant parasitic nematodes secrete a cocktail of effector molecules, which are involved in several aspects the interaction with host, eg. host defense suppression, migration and feeding cell formation. In this thesis, we performed first study on 10 novel peptide genes, believed to be important for parasitism potato cyst nematode, Globodera rostochiensis. Nine genes described here belong SECPEP gene family. The all expressed dorsal esophageal gland, is one main sites production molecules. This, together predominant expression preparasitic early juvenile nematodes, makes it very likely that SECPEPs code peptides essential succesful infection site chapter 2, show diversifying selection driver molecular evolution SECPEPs. sequences mature appear highly diverse, while non)coding 3’UTR intronic regions as well region coding signal secretion relatively conserved. fact, pairwise comparison reveals no significant sequence similarity between family members at all. 5 further speculate possible role RNA)editing mechanism yield hypervariability SECPEPs, because diversity transcript level significantly exceeds genomic locus. Chapter elaborates analysis trans)splicing SECPEP1 transcripts. We transcripts trans)spliced surprising spliced)leader sequences. approach unravel plant parasitism, 4. generated transgenic Arabidopsis plants expressing SECPEP3 using CaMV 35S promotor. phenotype associated both includes reduction root growth an alteration leaf morphology. harbors motifs found cyclin)dependent kinase inhibitors ICK1/KRP1, SIM Smr1. We, therefore, suggest cycle nematode Although only low primary similarity, positively charged, hydrophilic C)x)G γ)core motif (chapter 2). These characteristics typical peptides, 6 investigate whether these also other plant)parasite interactions. considerable number share positive charge, hydrophilicity charge peptide)ligand interaction. 3 describe NEMPEP peptide, secreted by G. motif, although genetically unrelated During life rostochiensis, pattern striking regulation. juveniles stages after initial However, was hardly detectable just entering root. Several disease resistance condition onset parasitism. downregulation exactly timepoint could strategy avoid recognition host’s immune system. planta NEMPEP, fusion GFP, shows accumulates nucleolus tobacco cells. Potato transformed 35S::NEMPEP were slow forming roots internodes leaflets shortened. reduced transformation efficiency, led us hypothesize cytokinin signaling (Chapter 3). Currently, there two models regarding functional NEMPEP. concerns antimicrobial protect against secondary infections opportunistic microbes. As competing hypothesis, high may point hormone. such, they redirecting or hormonal regulation upon