Biology subjects

Mojerlou, S.

Publications and source records attributed to Mojerlou, S..

3 recordsLinked to original sources

bioRxiv2026

The variable wheat stripe rust effector AvrYr7 evades Yr7 recognition through sequence and expression polymorphisms

Introductory paragraphWheat provides about 20% of total dietary calories worldside1. Wheat diseases, including wheat stripe (yellow) rust, cause billions of dollars in losses each year2. Wheat stripe (yellow) rust is caused by the fungal pathogen Puccinia striiformis f. sp. tritici (Pst) which is best controlled by fungicide application and disease resistant wheat cultivars3. To-date, there are over 80 catalogued and >10 cloned yellow rust resistance genes (Yr genes)4. Yet our knowledge of corresponding avirulence (Avr) genes lags far behind5-8. The absence of cloned Avrs reflects Psts complex genome and the lack of robust transformation and genetic systems3. Recent advances in generating high-quality genome assemblies and the development of wheat defense assays have addressed these challenges9-11. Here we clone AvrYr7 which is recognized by Yr712. We further identify six additional alleles of AvrYr7 that escape recognition due to non-synonymous genetic variations, transposable element activity, missense mutation, and expression polymorphism. These findings provide critical insights into virulence evolution in one of the worlds most important wheat pathogens.

plant biology↗

bioRxiv2026

Sexual recombination under tetrapolar mating can alter host-specialization boundaries between wheat- and barley-adapted stripe rust lineages

O_LIHost specialization is a major driver of genetic structure in fungal plant pathogens, but it remains unclear whether specialization on different cereal hosts prevents sexual recombination when mating-type compatibility is retained. We addressed this question in stripe rust, caused by Puccinia striiformis, by crossing wheat-adapted P. striiformis f. sp. tritici and barley-adapted P. striiformis f. sp. hordei, two divergent host-adapted forms that share common barberry (Berberis vulgaris) as a sexual host. C_LIO_LIControlled reciprocal crosses on barberry produced 18 aeciospore-derived progeny, demonstrating that wheat- and barley-adapted Puccinia striiformis can undergo sexual recombination despite strong host specialization during asexual infection. Chromosome-scale parental assemblies placed the homeodomain (HD) mating-type locus, containing bW-HD1 and bE-HD2, on chromosome 2 and the pheromone receptor (PR) mating-type locus, containing STE3 and mfa genes, on chromosome 6. HD restriction genotyping showed biparental inheritance in all progeny, with each progeny carrying one HD haplotype from each parent. Together with conservation of PR-associated coding sequences and amplification of STE3-associated markers in progeny, these results are consistent with retention of tetrapolar mating across the two host-adapted lineages. C_LIO_LIHost interaction phenotypes were assessed across wheat and barley differentials, near-isogenic lines and wild relatives. The parental isolates retained contrasting wheat- and barley-restricted profiles, whereas progeny did not reproduce either parental virulence profile, but instead showed recombinant infection patterns, including compatibility with both wheat and barley genotypes. C_LIO_LIThese findings indicate that host specialization in Puccinia striiformis does not necessarily prevent sexual compatibility on a shared alternate host. Together with retention of tetrapolar mating, alternate-host sexual reproduction may provide a route for genetic exchange between host-specialized pathogen populations, enabling recombination to generate new combinations of host-interaction traits when divergent pathogen lineages mate on a shared alternate host. C_LI

microbiology↗

bioRxiv2026

A chromosome-scale, haplotype-resolved genome assembly of the barley stripe rust pathogen Puccinia striiformis f. sp. hordei

Puccinia striiformis f. sp. hordei (Psh) causes barley stripe rust, an economically important disease affecting barley production across multiple temperate regions. Unlike its well-studied wheat-infecting relative P. striiformis f. sp. tritici, genomic resources for Psh remain limited, with no fully documented chromosome-scale, haplotype-resolved reference genomes publicly available. Here we present a high-quality, haplotype-resolved genome assembly of the dikaryotic Psh isolate NP85002, generated using Oxford Nanopore long-read sequencing combined with Hi-C chromatin conformation capture. The assembly comprises 18 chromosomes per haplotype (151.3 Mb total) including 33 telomere-to-telomere chromosomes, telomeric repeats at 69/72 chromosome ends, and six internal gaps. The assembly shows high consensus accuracy (QV >72) and strong haplotype separation (97.54% within-haplotype Hi-C contacts). Genome completeness reached 90.1% complete BUSCOs, and a combined lift-over plus ab initio annotation achieved 94.4% complete BUSCOs. Repeat annotation indicates 45% repetitive content. We additionally provide a 102,058 bp mitochondrial genome assembly with 40 annotated genes. This genome resource provides a chromosome-scale framework for comparative and population genomic analyses of barley stripe rust and related cereal rust pathogens.

microbiology↗