Plant cells secrete chitinases, which, when the plant is infected with fungi, break down their chitin. The resulting breakdown products are recognized by specialized immune receptors and trigger a series of defense responses of plant cells to chitin. In this study we reported a chitin-binding protein, VnaChtBP, secreted by the phytopathogenic fungus Verticillium nonalfalfae, protects the from degradation by plant chitinases and suppresses the plant-induced immune response of chitin. In collaboration with research groups from Wageningen University & Research and the James Hutton Institute, we were the first to elucidate the molecular mechanism of chitin binding, which, unlike already known chitin-associated fungal proteins with LysM or Avr4 domains, includes a structurally different CBM18 motif. The key common function of these proteins is preventing the breakdown of the fungal cell wall and suppressing the immune response of plants. The publication was Molecular plant-microbe interactions (APS Press) magazine's editor's pick for October in 2020 and was their most often downloaded article in 2020.
COBISS.SI-ID: 9214841
Testing inbred lines for their combining ability is, due to high numbers of line to line testing needed for determination of hybrid performance, the most limiting factor in the F1 hybrid breeding procedure. We propose a novel method of F1 hybrid breeding that enables evaluation of large number of line to line crosses for their hybrid performance. Inbred lines (preferably doubled haploid - DH) are produced from heterozygous populations, genotyped and maintained. A group of lines is inter-pollinated randomly and their progeny examined. To identify elite F1 hybrids, these individual plants are selected by their superior phenotypic characteristics. Finally using paternity testing only of selected hybrids, the origin of paternal lines is revealed. To predict the number of F1 offspring needed in relation to the number of inbred lines being inter-pollinated, a mathematical formula was developed. For instance, using this formula for the inter-pollination of 60 distinct lines, the probability of obtaining all descendants of paternal-parent lines in a maternal-parent row represented at least once is achieved with 420 F1 plants in a row (p = 0.95). In a practical experiment with white cabbage, DH lines were produced using microspore culture; plants were grown to maturity and genotyped at eight polymorphic SSR loci. Two groups of lines (36 and 33 lines per group) were inter-pollinated by two methods, either using cage pollination with bumblebees or using open pollination in isolated field. A total of 9,858 F1 plants were planted and based on their phenotypic characteristics 213 were selected as elite phenotypes. 99 of them were genetically diverse and 5 of them were selected as super elite. Selected plants were analysed by the same SSR markers and the paternal origin of selected F1 plants was determined. Out of 213 selected elite plants 48 were reciprocals thus exhibiting power of selection based on single plant. We demonstrate that this new approach to hybrid development is efficient in white cabbage and we propose breeders to test it in various vegetable and crop species. Moreover, some other aspects of the proposed technique need to be tested and verified both for practical and economic criteria.
COBISS.SI-ID: 9287289
Viroids are small non-capsidated, single-stranded, covalently-closed circular noncoding RNA replicons of 239-401 nucleotides that exploit host factors for their replication, and some cause disease in several economically important crop plants, while others appear to be benign. The proposed mechanisms of viroid pathogenesis include direct interaction of the genomic viroid RNA with host factors and post-transcriptional or transcriptional gene silencing via viroid-derived small RNAs (vd-sRNAs) generated by the host defensive machinery. Humulus lupulus (hop) plants are hosts to several viroids among which Hop latent viroid (HLVd) and Citrus bark cracking viroid (CBCVd) are attractive model systems for the study of viroid-host interactions due to the symptomless infection of the former and severe symptoms induced by the latter in this indicator host. To better understand their interactions with hop plant, a comparative transcriptomic analysis based on RNA sequencing (RNA-seq) was performed to reveal the transcriptional alterations induced as a result of single HLVd and CBCVd infection in hop. Additionally, the effect of HLVd on the aggressiveness of CBCVd that underlies severe stunting in hop in a mixed infection was studied by transcriptomic analysis. Our analysis revealed that CBCVd infection resulted in dynamic changes in the activity of genes as compared to single HLVd infection and their mixed infection. The differentially expressed genes that are involved in defense, phytohormone signaling, photosynthesis and chloroplasts, RNA regulation, processing and binding; protein metabolism and modification; and other mechanisms were more modulated in the CBCVd infection of hop. Nevertheless, Gene Ontology (GO) classification and pathway enrichment analysis showed that the expression of genes involved in the proteolysis mechanism is more active in a mixed infection as compared to a single one, suggesting co-infecting viroids may result in interference with host factors more prominently. Collectively, our results provide a deep transcriptome of hop and insight into complex single HLVd, CBCVd, and their coinfection in hop-plant interactions.
COBISS.SI-ID: 9268089
The conserved RNA interference mechanism (RNAi) in the fungal kingdom has become a focus of intense scientific investigation. The three catalytic core components, Dicer-like (DCL), Argonaute (AGO), and RNA-dependent RNA polymerase (RdRP), and their associated small interfering RNA molecules (siRNAs) have been identified and characterised in several fungal species. Recent studies have proposed that RNAi is a major contributor to the virulence of fungal pathogens as a result of so-called trans-kingdom RNA silencing. In the present study, we report on the existence of three core RNAi proteins in the pathogenic plant fungus Verticillium nonalfalfae, which is a soilborne plant pathogen that causes severe wilting disease in hops (Humulus lupulus L.). Two DCL proteins, two AGO proteins, and two RdRP proteins were identified, and their conserved RNAi domains were characterised. Our phylogeny results confirm the existing taxonomic relationships in the Ascomycete fungal phylum and show that the fungi of the Hypocreomycetidae subclass of the Sordariomycetes class have high amino acid sequence similarity. The expression analysis revealed a potential role of RNAi in the pathogenicity of the fungi, since all the RNAi genes were highly upregulated in the highly virulent isolate T2 and were also differentially expressed in the V. nonalfalfae-susceptible Celeia and V. nonalfalfae-resistant Wye Target cultivars.
COBISS.SI-ID: 9242233
CRISPR/Cas9 is a versatile and highly efficient genome editing tool used in many different plant species. In the present study, we compared the two most commonly used transient expression methods for genome editing, protoplast transfection and infiltration of Agrobacterium tumefaciens, to develop a rapid and efficient validation protocol. Vectors designed to target four different sites in the cabbage genome (two of which were model target genes and two related to the centromere-specific histone H3 (CENH3) gene) were delivered to two red cabbage cultivars, ‘Huzaro F1’ and ‘Rebecca F1’. Targeted deep sequencing analysis showed that CRISPR/Cas9 vectors induced mutations in both cultivars at all target sites and revealed mutation rates of 1.27–11.95% for protoplast transfection and 0.07–14.42% for agroinfiltration. Our results demonstrate successful genome editing in cabbage with CRISPR/Cas9 by two different approaches for the rapid evaluation of genome editing efficiency. Results were presented at international conference (Brassica 2018: 21st Crucifer Genetics conference, St. Malo, France) and annual meetings of Genetics Society of Slovenia.
COBISS.SI-ID: 9287545