Biology subjects

Rodriguez-Algaba, J.

Publications and source records attributed to Rodriguez-Algaba, J..

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↗

bioRxiv2023

New races with wider virulence indicate local evolution of Puccinia striiformis f. sp. tritici in South America

Wheat yellow (stripe) rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most devastating diseases of wheat worldwide. Pst populations are composed of multiple genetic groups, each carrying one or more races characterized by different avirulence/virulence combinations. Since the severe epidemics in 2017, yellow rust has become the most economically important wheat foliar disease in Uruguay. Evolution of virulence was investigated based on genotyping and race typing of a representative set of 27 Pst isolates collected from wheat fields in Uruguay between 2017 and 2021. Three genetic groups were identified, i.e., PstS7, PstS10 and PstS13, the latter being the most prevalent. Two races previously reported in Europe, Warrior (PstS7) and Benchmark (PstS10), were detected in four and two isolates, respectively. A third race known as Triticale2015 (PstS13), first detected in Europe in 2015 and in Argentina in 2017, was detected at several locations. Additional virulence to Yr3, Yr17, Yr25, Yr27 or Yr32 was detected in three new race variants within PstS13. The identification of these new races, which have not been reported outside South America, provides strong evidence of the local evolution of virulence in Pst during the recent epidemic years.

pathology↗