Signalling Crosstalk of Plant Defence Responses to Xylem-invading Pathogens

Xylem is a plant vascular tissue that transports water and dissolved minerals from the roots to the rest of the plant. It consists of specialized water-conducting tracheary elements, supporting fibre cells and storage parenchyma cells. Certain plant pathogenic fungi, oomycetes and bacteria have evolved strategies to invade xylem vessels and cause highly destructive vascular wilt diseases that affect the crop production and forest ecosystems worldwide. In this chapter, we consider the molecular mechanisms of root-specific defence responses against vascular wilt pathogens, with an emphasis on the most important and well-studied fungal (Verticillium spp. and Fusarium oxysporum) and bacterial (Xanthomonas spp. and Ralstonia solanacearum) pathogens. In particular, we present the current understanding of plant immune responses, from invasion perception to signal transduction and termination. Furthermore, we address the role of specific transcription factors involved in plant immunity and their regulatory network. We also highlight the crucial roles of phytohormones as signalling molecules in local and systemic defence responses. Finally, we summarize the current knowledge of plant defence responses to xylem-invading pathogens to devise new strategies and methods for controlling these destructive plant pathogens

Određivanje DNA otiska različitih sorta masline pomoću mikrosatelitskih markera

Microsatellites combine several features of an ultimate molecular marker and they are used increasingly in various plant genetic studies and applications. In this work we report on the utilisation of fourteen previously developed olive microsatellite markers for the identification and differentiation of a set of nineteen olive varieties. All analysed microsatellite markers revealed a high level of polymorphism that allowed unique genotyping of the examined varieties. Ninety-six alleles were detected at all 14 loci, which multiplied into a large number of observed genotypes, giving high discrimination value for varietal identification. A minimum number of three microsatellite markers was chosen for the rapid and unambiguous varietal identification of nineteen olive varieties and only two markers were sufficient for differentiation of five local varieties. DNA fingerprints of olive cultivars by means of microsatellites provided meaningful data, which can be extended by additional olive varieties or new microsatellites and used for accurate inter-laboratory comparison. The data obtained can be used for the varietal survey and construction of a database of all olive varieties grown in Slovenia providing also additional genetic information on the agronomic and quality characteristics of the olive varieties.U različitim genetičkim istraživanjima biljaka sve se više koriste mikrosateliti kao najpogodniji molekularni marker. U četrnaest analiziranih lokusa otkriveno je ukupno 96 alela, što omogućava vrlo veliku razlikovnost pri identifikaciji pojedinih sorta. Tipiziranjem genoma različitih sorta masline pomoću mikrosatelita dobivene su vrlo korisne informacije koje se mogu dopuniti uporabom dodatnih markera. Tom se metodologijom mogu karakterizirati i nove sorte maslina, a i obavljati pouzdane međulaboratorijske usporedbe rezultata. Dobiveni podaci mogu se koristiti pri izradbi baze podataka za identifikaciju pojedinih sorta i njihovu rasprostranjenost na području Slovenije. Oni također omogućavaju da se agronomske značajke i kakvoća različitih vrsta maslina dopune dodatnim genetičkim informacijama

Complete mitochondrial genome of the Verticillium-wilt causing plant pathogen Verticillium nonalfalfae

Verticillium nonalfalfae is a fungal plant pathogen that causes wilt disease by colonizing the vascular tissues of host plants. The disease induced by hop isolates of V. nonalfalfae manifests in two different forms, ranging from mild symptoms to complete plant dieback, caused by mild and lethal pathotypes, respectively. Pathogenicity variations between the causal strains have been attributed to differences in genomic sequences and perhaps also to differences in their mitochondrial genomes. We used data from our recent Illumina NGS-based project of genome sequencing V. nonalfalfae to study the mitochondrial genomes of its different strains. The aim of the research was to prepare a V. nonalfalfae reference mitochondrial genome and to determine its phylogenetic placement in the fungal kingdom. The resulting 26,139 bp circular DNA molecule contains a full complement of the 14 "standard" fungal mitochondrial protein-coding genes of the electron transport chain and ATP synthase subunits, together with a small rRNA subunit, a large rRNA subunit, which contains ribosomal protein S3 encoded within a type IA-intron and 26 tRNAs. Phylogenetic analysis of this mitochondrial genome placed it in the Verticillium spp. lineage in the Glomerellales group, which is also supported by previous phylogenetic studies based on nuclear markers. The clustering with the closely related Verticillium dahliae mitochondrial genome showed a very conserved synteny and a high sequence similarity. Two distinguishing mitochondrial genome features were also found-a potential long non-coding RNA (orf414) contained only in the Verticillium spp. of the fungal kingdom, and a specific fragment length polymorphism observed only in V. dahliae and V. nubilum of all the Verticillium spp., thus showing potential as a species specific biomarker

Proteomički pristup istraživanju pčelinjih proizvoda, tj. matične mliječi, propolisa i meda

Bee products such as royal jelly, honey and propolis have been reported to possess several biological activities. In order to better understand their mechanism of action and, consequently, their efficiency and safety, \u27omic\u27 approaches are used. Here cases with proteomic approach are indicated. In addition to studying biological activity at a proteome level, a proteomic approach for investigation of bee products has also been applied in analyzing proteins as their (bioactive) components.Pčelinji proizvodi, kao što su matična mliječ, med i propolis, imaju višestruku ulogu u biološkim procesima. U ovom su radu prikazane proteomičke metode koje se koriste za proučavanje mehanizma njihova djelovanja i sigurnosti hrane. Proteomički je pristup, osim za proučavanje biološke aktivnosti pčelinjih proizvoda na molekularnoj razini, primijenjen i pri analizi proteina, tj. bioaktivnih sastojaka tih proizvoda

Complete mitochondrial genome of the Verticillium-wilt causing plant pathogen Verticillium nonalfalfae

Verticillium nonalfalfae is a fungal plant pathogen that causes wilt disease by colonizing the vascular tissues of host plants. The disease induced by hop isolates of V. nonalfalfae manifests in two different forms, ranging from mild symptoms to complete plant dieback, caused by mild and lethal pathotypes, respectively. Pathogenicity variations between the causal strains have been attributed to differences in genomic sequences and perhaps also to differences in their mitochondrial genomes. We used data from our recent Illumina NGS-based project of genome sequencing V. nonalfalfae to study the mitochondrial genomes of its different strains. The aim of the research was to prepare a V. nonalfalfae reference mitochondrial genome and to determine its phylogenetic placement in the fungal kingdom. The resulting 26,139 bp circular DNA molecule contains a full complement of the 14 "standard" fungal mitochondrial protein-coding genes of the electron transport chain and ATP synthase subunits, together with a small rRNA subunit, a large rRNA subunit, which contains ribosomal protein S3 encoded within a type IA-intron and 26 tRNAs. Phylogenetic analysis of this mitochondrial genome placed it in the Verticillium spp. lineage in the Glomerellales group, which is also supported by previous phylogenetic studies based on nuclear markers. The clustering with the closely related Verticillium dahliae mitochondrial genome showed a very conserved synteny and a high sequence similarity. Two distinguishing mitochondrial genome features were also found—a potential long non-coding RNA (orf414) contained only in the Verticillium spp. of the fungal kingdom, and a specific fragment length polymorphism observed only in V. dahliae and V. nubilum of all the Verticillium spp., thus showing potential as a species specific biomarker.The mitochondrial genome sequence is available from the Genbank database (accession number KR704425). NGS sequencing data are available in the SRA database (Bioproject PRJNA283258).Supporting Information: S1 Fig. Secondary structures of predicted tRNA molecules. (TIF)Supporting Information: S2 Fig. Alignment of V. nonalfalfae reads to the V. dahliae mitochondrial genome. (TIF)Supporting Information: S1 File. BLAST results of orf414 analysis. (DOC)Supporting Information: Mitochondrial genome of Verticillium nonalfalfae PLOS ONE | DOI:10.1371/journal.pone.0148525 February 3, 2016 14 / 18 S1 Table. V. nonalfalfae codon usage statistics. (DOC) S2 Table. Collection of Verticillium species included in analysis of the mitochondrial length polymorphism. (XLS) Remove selectedSupporting Information: Mitochondrial genome of Verticillium nonalfalfae PLOS ONE | DOI:10.1371/journal.pone.0148525 February 3, 2016 14 / 18Supporting Information: S2 Table. Collection of Verticillium species included in analysis of the mitochondrial length polymorphism. (XLS)Supporting Information: S1 Table. V. nonalfalfae codon usage statistics. (DOC)VJ received the grant - Javni sklad Republike Slovenije za razvoj kadrov in štipendije - 163. JR (http://www.sklad-kadri.si) BJ received the grant - Javna agencija za raziskovalno dejavnost Republike Slovenije - P4-0077 (www.arrs.gov.si)http://www.plosone.orgam2016Genetic

Chitin-Binding Protein of Verticillium nonalfalfae Disguises Fungus from Plant Chitinases and Suppresses Chitin-Triggered Host Immunity

During fungal infections, plant cells secrete chitinases, which digest chitin in the fungal cell walls. The recognition of released chitin oligomers via lysin motif (LysM)-containing immune host receptors results in the activation of defense signaling pathways. We report here that Verticillium nonalfalfae, a hemibiotrophic xylem-invading fungus, prevents these digestion and recognition processes by secreting a carbohydrate-binding motif 18 (CBM18)-chitin-binding protein, VnaChtBP, which is transcriptionally activated specifically during the parasitic life stages. VnaChtBP is encoded by the Vna8.213 gene, which is highly conserved within the species, suggesting high evolutionary stability and importance for the fungal lifestyle. In a pathogenicity assay, however, Vna8.213 knockout mutants exhibited wilting symptoms similar to the wild-type fungus, suggesting that Vna8.213 activity is functionally redundant during fungal infection of hop. In a binding assay, recombinant VnaChtBP bound chitin and chitin oligomers in vitro with submicromolar affinity and protected fungal hyphae from degradation by plant chitinases. Moreover, the chitin-triggered production of reactive oxygen species from hop suspension cells was abolished in the presence of VnaChtBP, indicating that VnaChtBP also acts as a suppressor of chitin-triggered immunity. Using a yeast-two-hybrid assay, circular dichroism, homology modeling, and molecular docking, we demonstrated that VnaChtBP forms dimers in the absence of ligands and that this interaction is stabilized by the binding of chitin hexamers with a similar preference in the two binding sites. Our data suggest that, in addition to chitin-binding LysM (CBM50) and Avr4 (CBM14) fungal effectors, structurally unrelated CBM18 effectors have convergently evolved to prevent hydrolysis of the fungal cell wall against plant chitinases and to interfere with chitin-triggered host immunity.</p