Указ президента України “Про проведення Всеукраїнської молодіжної акції “Пам’ятати. Відродити. Зберегти”

Genetic dissection of disease susceptibility in Arabidopsis to powdery and downy mildew has identified multiple susceptibility (S) genes whose impairment results in disease resistance. Although several of these S-genes have been cloned and characterized in more detail it is unknown to which degree their function in disease susceptibility is conserved among different plant species. Moreover, it is unclear whether impairment of such genes has potential in disease resistance breeding due to possible fitness costs associated with impaired alleles. Here we show that the Arabidopsis PMR4 and DMR1, genes encoding a callose synthase and homoserine kinase respectively, have functional orthologs in tomato with respect to their S-gene function. Silencing of both genes using RNAi resulted in resistance to the tomato powdery mildew fungus Oidium neolycopersici. Resistance to O. neolycopersici by SlDMR1 silencing was associated with severely reduced plant growth whereas SlPMR4 silencing was not. SlPMR4 is therefore a suitable candidate gene as target for mutagenesis to obtain alleles that can be deployed in disease resistance breeding of tomato

ZED1-related kinase 13 is required for resistance against Pseudoidium neolycopersici in Arabidopsis accession Bla-6

To explore specific components of resistance against the tomato-adapted powdery mildew pathogen Pseudoidium neolycopersici (On) in the model plant Arabidopsis, we performed a disease assay in 123 accessions. When testing the resistance in the F1 from crossings between resistant accessions with susceptible Col-0 or Sha, only the progeny of the cross between accession Bla-6 and Col-0 displayed a completely resistant phenotype. The resistance in Bla-6 is known to be specific for Pseudoidium neolycopersici. QTL analysis and fine-mapping through several rounds of recombinant screenings allowed us to locate a major resistance QTL in an interval on chromosome 1, containing two candidate genes and an intergenic insertion. Via CRISPR/Cas9 targeted mutagenesis, we could show that knocking out the ZED-1 RELATED KINASE 13 (ZRK13) gene compromised the On resistance in Bla-6. Several polymorphisms are observed in the ZRK13 allelic variant of Bla-6 when compared to the Col-0 protein

Balanced Nuclear and Cytoplasmic Activities of EDS1 Are Required for a Complete Plant Innate Immune Response

An important layer of plant innate immunity to host-adapted pathogens is conferred by intracellular nucleotide-binding/ oligomerization domain-leucine rich repeat (NB-LRR) receptors recognizing specific microbial effectors. Signaling from activated receptors of the TIR (Toll/Interleukin-1 Receptor)-NB-LRR class converges on the nucleo-cytoplasmic immune regulator EDS1 (Enhanced Disease Susceptibility1). In this report we show that a receptor-stimulated increase in accumulation of nuclear EDS1 precedes or coincides with the EDS1-dependent induction and repression of defense-related genes. EDS1 is capable of nuclear transport receptor-mediated shuttling between the cytoplasm and nucleus. By enhancing EDS1 export from inside nuclei (through attachment of an additional nuclear export sequence (NES)) or conditionally releasing EDS1 to the nucleus (by fusion to a glucocorticoid receptor (GR)) in transgenic Arabidopsis we establish that the EDS1 nuclear pool is essential for resistance to biotrophic and hemi-biotrophic pathogens and for transcriptional reprogramming. Evidence points to post-transcriptional processes regulating receptor-triggered accumulation of EDS1 in nuclei. Changes in nuclear EDS1 levels become equilibrated with the cytoplasmic EDS1 pool and cytoplasmic EDS1 is needed for complete resistance and restriction of host cell death at infection sites. We propose that coordinated nuclear and cytoplasmic activities of EDS1 enable the plant to mount an appropriately balanced immune response to pathoge

Arabidopsis <i>DMR1</i> is a S-gene for the tomato powdery mildew <i>Oidium neolycopersici</i>.

<p>(<b>A–F</b>), Photograph of L<i>er eds1-2</i> (A), <i>dmr1-3</i> (B), <i>dmr1-6</i> (C), <i>dmr1-1</i> (D), <i>dmr1-2</i> (E) and <i>dmr1-5</i> (F) at 14 days post inoculations (dpi) with <i>O. neolycopersici</i>. (<b>G</b>), Quantification of <i>O. neolycopersici</i> growth at 14 dpi by Disease Index (DI) score (see M&M). (<b>H</b>), Fresh weight of 5 weeks old L<i>er eds1-2</i> and <i>dmr1</i> mutant plants. Fresh weights are given as percentage of the parental line L<i>er eds1-2</i>. For <b>G</b> and <b>H</b>. Data indicate the mean of 3 or more biological replicates with error bars representing the standard error. Number of asterisks indicate degree of significance (***p<0.001).</p

Powdery mildew resistance by impairment of <i>PMR4</i> is conserved between Arabidopsis and tomato.

<p>(<b>A and B</b>), Leaf of T2 plant 4–5 (A) carrying a <i>RNAi::SlPMR4</i> silencing construct (+) and of T2 plant 4–4 (B) without silencing construct (−) at the age of 5 weeks and 8 days post <i>O. neolycopersici</i> inoculation. (<b>C</b>), Relative <i>SlPMR4</i> transcript levels in untransformed Moneymaker (MM) plants and progeny of 3 independent T1 plants transformed with a silencing construct specifically targeting <i>SlPMR4</i> (family 2, 3 and 4). T2 progenies harbouring a silencing construct (RNAi::<i>SlPMR4</i> (+)) showed significantly lower transcript levels compared to untransformed Moneymaker plants and progenies not harbouring a silencing construct (−) as indicated by asterisks. (<b>D</b>), Quantification of fungal growth of lines mentioned in (C). <i>SlPMR4</i> silenced plants show significantly less fungal growth compared to non-silenced plants as indicated by asterisks, demonstrating that <i>SlPMR4</i> is a functional ortholog of <i>PMR4</i>. (<b>E and F</b>), Relative plant height and stem diameter of 12 week old plants respectively. A slight reduction (although significant as indicated by asterisks) in plant height was observed for progenies carrying a <i>RNAi::SlPMR4</i> construct of families 2 and 3, but not 4. Stem diameters were somewhat lower among T1 progenies of all 3 families, but differences were not statistically significant. For <b>C</b>, <b>D</b>, <b>E</b> and <b>F</b>, data indicate the mean of 3 or more biological replicates with error bars representing the standard error. Number of asterisks indicate degree of significance (**p<0.01; ***p<0.001).</p

Tomato <i>SlDMR1</i> is a S-gene for the tomato powdery mildew <i>Oidium neolycopersici</i>.

<p>(<b>A</b>), relative transcript abundance of <i>SlDMR1</i> in multiple independent cuttings of untransformed Moneymaker (MM) plants or T1 transformants harbouring an RNAi::<i>SlDMR1</i> construct (Line2, 3 and 5). (<b>B</b>), Quantification of fungal growth at 8 days post inoculation (dpi). <i>SlDMR1</i> silenced plants support significantly less fungal growth compared to untransformed plants. (<b>C</b>), Leaves of an untransformed MM and <i>SlDMR1</i> silenced plant at 8 dpi. Silencing of <i>SlDMR1</i> results in reduced leaf size and yellowish colour. For <b>A</b> and <b>B</b>. Data indicate the mean of 3 or more biological replicates with error bars representing the standard error. Number of asterisks indicate degree of significance (***p<0.001).</p

Exogenous application of L-homoserine induced <i>Oidium neolycopersici</i> resistance and necrosis in tomato.

<p>(<b>A</b>), Quantification of fungal growth, 8 days post inoculations of Moneymaker (MM) plants sprayed with different amino-acid solutions prior to pathogen inoculations. Spray application of L-homoserine reduces fungal growth significantly compared to spray application of H₂O or isoleucine, leucine, threonine or valine. Data indicate the mean of 3 or more biological replicates with error bars representing the standard error. Number of asterisks indicate degree of significance (***p<0.001). (<b>B–C</b>), Spray application of L-homoserine induces cell death in MM plants whereas the H₂O control does not.</p

Impairment of <i>PMR4</i> in Arabidopsis results in resistance to tomato powdery mildew <i>Oidium neolycopersici</i>.

<p>(<b>A and B</b>), Col-0 and <i>pmr4</i> mutant plants photographed 14 days post inoculation with <i>Oidium neolycopersici</i>. Fungal sporulation is visible as whitish powder on multiple leaves of Col-0 but not on <i>pmr4</i> mutants, showing that Arabidopsis <i>PMR4</i> is a susceptibility (<i>S</i>) gene for <i>O. neolycopersici</i>. (<b>C</b>), Phylogenetic tree of Arabidopsis PMR4 family members plus tomato PMR4 family orthologs. The protein SlPMR4_h1 encoded by the tomato gene <i>Solyc07g053980</i> is considered to be the tomato ortholog of AtPMR4.</p