Plant disease resistance

About: Plant disease resistance is a research topic. Over the lifetime, 12952 publications have been published within this topic receiving 381820 citations. The topic is also known as: plant innate immunity.

Fusarium graminearum exploits ethylene signalling to colonize dicotyledonous and monocotyledonous plants

Abstract: Summary • Ethylene signalling affects the resistance of dicotyledonous plant species to diverse pathogens but almost nothing is known about the role of this pathway in monocotyledonous crop species. Fusarium graminearum causes Fusarium head blight (FHB) of cereals, contaminating grain with mycotoxins such as deoxynivalenol (DON). Very little is known about the mechanisms of resistance/susceptibility to this disease. • Genetic and chemical genetic studies were used to examine the influence of ethylene (ET) signalling and perception on infection of dicotyledonous (Arabidopsis) and monocotyledonous (wheat and barley) species by F. graminearum. • Arabidopsis mutants with reduced ET signalling or perception were more resistant to F. graminearum than wild-type, while mutants with enhanced ET production were more susceptible. These findings were confirmed by chemical genetic studies of Arabidopsis, wheat and barley. Attenuation of expression of EIN2 in wheat, a gene encoding a core component of ethylene signalling, reduced both disease symptoms and DON contamination of grain. • Fusarium graminearum appears to exploit ethylene signalling in both monocotyledonous and dicotyledonous species. This demonstration of translation from model to crop species provides a foundation for improving resistance of cereal crops to FHB through identification of allelic variation for components of the ethylene-signalling pathway.

Wheat Stripe Rust Resistance Protein WKS1 Reduces the Ability of the Thylakoid-Associated Ascorbate Peroxidase to Detoxify Reactive Oxygen Species.

Abstract: Stripe rust is a devastating fungal disease of wheat caused by Puccinia striiformis f sp tritici (Pst) The WHEAT KINASE START1 (WKS1) resistance gene has an unusual combination of serine/threonine kinase and START lipid binding domains and confers partial resistance to Pst Here, we show that wheat (Triticum aestivum) plants transformed with the complete WKS1 (variant WKS11) are resistant to Pst, whereas those transformed with an alternative splice variant with a truncated START domain (WKS12) are susceptible WKS11 and WKS12 preferentially bind to the same lipids (phosphatidic acid and phosphatidylinositol phosphates) but differ in their protein-protein interactions WKS11 is targeted to the chloroplast where it phosphorylates the thylakoid-associated ascorbate peroxidase (tAPX) and reduces its ability to detoxify peroxides Increased expression of WKS11 in transgenic wheat accelerates leaf senescence in the absence of Pst Based on these results, we propose that the phosphorylation of tAPX by WKS11 reduces the ability of the cells to detoxify reactive oxygen species and contributes to cell death This response takes several days longer than typical hypersensitive cell death responses, thus allowing the limited pathogen growth and restricted sporulation that is characteristic of the WKS1 partial resistance response to Pst

QTL mapping of fire blight resistance in apple

Abstract: Fire blight caused by the bacterium Erwinia amylovora is a severe threat to apple and pear orchards worldwide. Apple varieties exhibit a wide range of relative susceptibility/tolerance to fire blight. Although, no monogenic resistance against fire blight has been identified yet, recent evidence indicates the existence of quantitative resistance. Potential sources of fire blight resistance include several wild Malus species and some apple cultivars. F1 progenies of ‘Fiesta’בDiscovery’ were inoculated with the Swiss strain Ea 610 and studied under controlled conditions to identify quantitative trait loci (QTLs) for fire blight resistance. Disease was evaluated at four time points after inoculation. Shoot lesion length and the area under disease progress curve (AUDPC) values were used for QTL analysis. One significant (LOD score of 7.5–8.1, p<0.001) QTL was identified on the linkage group 7 of ‘Fiesta’ (F7). The F7 QTL explained about 37.5–38.6% of the phenotypic variation.

Functions of rice NAC transcriptional factors, ONAC122 and ONAC131, in defense responses against Magnaporthe grisea

Abstract: NAC (NAM/ATAF/CUC) transcription factors have important functions in regulating plant growth, development, and abiotic and biotic stress responses. Here, we characterized two rice pathogen-responsive NAC transcription factors, ONAC122 and ONAC131. We determined that these proteins localized to the nucleus when expressed ectopically and had transcriptional activation activities. ONAC122 and ONAC131 expression was induced after infection by Magnaporthe grisea, the causal agent of rice blast disease, and the M. grisea-induced expression of both genes was faster and higher in the incompatible interaction compared with the compatible interaction during early stages of infection. ONAC122 and ONAC131 were also induced by treatment with salicylic acid, methyl jasmonate or 1-aminocyclopropane-1-carboxylic acid (a precursor of ethylene). Silencing ONAC122 or ONAC131 expression using a newly modified Brome mosaic virus (BMV)-based silencing vector resulted in an enhanced susceptibility to M. grisea. Furthermore, expression levels of several other defense- and signaling-related genes (i.e. OsLOX, OsPR1a, OsWRKY45 and OsNH1) were down-regulated in plants silenced for ONAC122 or ONAC131 expression via the BMV-based silencing system. Our results suggest that both ONAC122 and ONAC131 have important roles in rice disease resistance responses through the regulated expression of other defense- and signaling-related genes.

Cytogenetically monitored transfer of powdery mildew resistance from rye into wheat.

Abstract: Powdery mildew, caused by the fungus Erysiphe graminis DC. ex Merat f. sp. tritici Em. Marchal, is a serious disease of cultivated bread wheat, Triticum aestivum L. em Thell. About 10 powdery mildew resistance genes are known in wheat and most of them are used in cultivar improvement. However, many of these genes were overcome by the fungus and are no longer effective and therefore, new sources of resistance are continuously being sought. Recently, we reported a new source of powdery mildew resistance, preliminarily designated MIP6L, that was derived from the long arm of chromosome 6R of Secale cereale L. cv. Prolific. The aim of this study was to transfer MIP6L to a cytologically stable wheat-rye chromosome translocation [...]