High-Copy Transposons from a Pathogen Give Rise to a Conserved sRNA Family with a Novel Host Immunity Target.

Small RNAs (sRNAs) are involved in gene silencing in multiple ways, including through cross-kingdom transfers from parasites to their hosts. Little is known about the evolutionary mechanisms enabling eukaryotic microbes to evolve functional mimics of host small regulatory RNAs. Here, we describe the identification and functional characterization of , an sRNA family derived from highly abundant short interspersed nuclear element (SINE) retrotransposons in the genome of the wheat powdery mildew pathogen.

The Avirulence Factor AvrStb6 Accumulates in Hyphae Close to Stomata and Triggers a Wheat Defense Response Hindering Fungal Penetration.

, the causal agent of Septoria tritici blotch, is one of Europe's most damaging wheat pathogens, causing significant economic losses. Genetic resistance is a common strategy to control the disease, being a resistance gene used for more than 100 years in Europe. This study investigates the molecular mechanisms underlying Stb6-mediated resistance.

A survey of lineage-specific genes in reveals de novo gene evolution from genomic raw material.

Diploid plant genomes typically contain ~35,000 genes, almost all belonging to highly conserved gene families. Only a small fraction are lineage-specific, which are found in only one or few closely related species. Little is known about how genes arise de novo in plant genomes and how often this occurs; however, they are believed to be important for plants diversification and adaptation.

Ancient variation of the gene in powdery mildew limits the effectiveness of the introgressed rye resistance gene in wheat.

Introgressions of chromosomal segments from related species into wheat are important sources of resistance against fungal diseases. The durability and effectiveness of introgressed resistance genes upon agricultural deployment is highly variable-a phenomenon that remains poorly understood, as the corresponding fungal avirulence genes are largely unknown. Until its breakdown, the resistance gene introgressed from rye to wheat provided broad resistance against powdery mildew ().

Chromosome-scale genome assembly provides insights into rye biology, evolution and agronomic potential.

Rye (Secale cereale L.) is an exceptionally climate-resilient cereal crop, used extensively to produce improved wheat varieties via introgressive hybridization and possessing the entire repertoire of genes necessary to enable hybrid breeding. Rye is allogamous and only recently domesticated, thus giving cultivated ryes access to a diverse and exploitable wild gene pool.

Wheat Pm4 resistance to powdery mildew is controlled by alternative splice variants encoding chimeric proteins.

Crop breeding for resistance to pathogens largely relies on genes encoding receptors that confer race-specific immunity. Here, we report the identification of the wheat Pm4 race-specific resistance gene to powdery mildew. Pm4 encodes a putative chimeric protein of a serine/threonine kinase and multiple C2 domains and transmembrane regions, a unique domain architecture among known resistance proteins.

Identification of specificity-defining amino acids of the wheat immune receptor Pm2 and powdery mildew effector AvrPm2.

Plant nucleotide-binding leucine-rich repeat receptors (NLRs) act as intracellular sensors for pathogen-derived effector proteins and trigger an immune response, frequently resulting in the hypersensitive cell death response (HR) of the infected host cell. The wheat (Triticum aestivum) NLR Pm2 confers resistance against the fungal pathogen Blumeria graminis f. sp.

Domestication of High-Copy Transposons Underlays the Wheat Small RNA Response to an Obligate Pathogen.

Plant genomes have evolved several evolutionary mechanisms to tolerate and make use of transposable elements (TEs). Of these, transposon domestication into cis-regulatory and microRNA (miRNA) sequences is proposed to contribute to abiotic/biotic stress adaptation in plants. The wheat genome is derived at 85% from TEs, and contains thousands of miniature inverted-repeat transposable elements (MITEs), whose sequences are particularly prone for domestication into miRNA precursors.

The AvrPm3-Pm3 effector-NLR interactions control both race-specific resistance and host-specificity of cereal mildews on wheat.

The wheat Pm3 resistance gene against the powdery mildew pathogen occurs as an allelic series encoding functionally different immune receptors which induce resistance upon recognition of isolate-specific avirulence (AVR) effectors from the pathogen. Here, we describe the identification of five effector proteins from the mildew pathogens of wheat, rye, and the wild grass Dactylis glomerata, specifically recognized by the PM3B, PM3C and PM3D receptors. Together with the earlier identified AVRPM3, the recognized AVRs of PM3B/C, (AVRPM3), and PM3D (AVRPM3) belong to a large group of proteins with low sequence homology but predicted structural similarities.

A chromosome-scale genome assembly reveals a highly dynamic effector repertoire of wheat powdery mildew.

Blumeria graminis f. sp. tritici (B.

Fungal resistance mediated by maize wall-associated kinase ZmWAK-RLK1 correlates with reduced benzoxazinoid content.

Wall-associated kinases (WAKs) have recently been identified as major components of fungal and bacterial disease resistance in several cereal crop species. However, the molecular mechanisms of WAK-mediated resistance remain largely unknown. Here, we investigated the function of the maize gene ZmWAK-RLK1 (Htn1) that confers quantitative resistance to northern corn leaf blight (NCLB) caused by the hemibiotrophic fungal pathogen Exserohilum turcicum.

Cereal powdery mildew effectors: a complex toolbox for an obligate pathogen.

Cereal powdery mildews are major pathogens of cultivated monocot crops, and all are obligate biotrophic fungi that can only grow and reproduce on living hosts. This lifestyle is combined with extreme host specialization where every mildew subspecies (referred to as forma specialis) can only infect one plant species. Recently there has been much progress in our understanding of the possible roles effectors play in this complex host-pathogen interaction.

Distinct domains of the AVRPM3 avirulence protein from wheat powdery mildew are involved in immune receptor recognition and putative effector function.

Recognition of the AVRPM3 avirulence protein from powdery mildew by the wheat PM3A/F immune receptor induces a hypersensitive response after co-expression in Nicotiana benthamiana. The molecular determinants of this interaction and how they shape natural AvrPm3 allelic diversity are unknown. We sequenced the AvrPm3 gene in a worldwide collection of 272 mildew isolates.

Non-parent of Origin Expression of Numerous Effector Genes Indicates a Role of Gene Regulation in Host Adaption of the Hybrid Triticale Powdery Mildew Pathogen.

Powdery mildew is an important disease of cereals. It is caused by one species, , which is divided into each of which is highly specialized to one host. Recently, a new form capable of growing on triticale () has emerged through hybridization between wheat and rye mildews ( and , respectively).

Rapid turnover of effectors in grass powdery mildew (Blumeria graminis).

Background: Grass powdery mildew (Blumeria graminis, Ascomycota) is a major pathogen of cereal crops and has become a model organism for obligate biotrophic fungal pathogens of plants. The sequenced genomes of two formae speciales (ff.spp.

AvrPm2 encodes an RNase-like avirulence effector which is conserved in the two different specialized forms of wheat and rye powdery mildew fungus.

There is a large diversity of genetically defined resistance genes in bread wheat against the powdery mildew pathogen Blumeria graminis (B. g.) f.

Hybridization of powdery mildew strains gives rise to pathogens on novel agricultural crop species.

Throughout the history of agriculture, many new crop species (polyploids or artificial hybrids) have been introduced to diversify products or to increase yield. However, little is known about how these new crops influence the evolution of new pathogens and diseases. Triticale is an artificial hybrid of wheat and rye, and it was resistant to the fungal pathogen powdery mildew (Blumeria graminis) until 2001 (refs.