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1. A haplotype‐resolved reference genome of Quercus alba sheds light on the evolutionary history of oaks

   https://doi.org/10.1111/nph.20463  

   Larson, Drew A; Staton, Margaret E; Kapoor, Beant; Islam‐Faridi, Nurul; Zhebentyayeva, Tetyana; Fan, Shenghua; Stork, Jozsef; Thomas, Austin; Ahmed, Alaa S; Stanton, Elizabeth C; et al (April 2025, New Phytologist)

   Summary White oak (Quercus alba) is an abundant forest tree species across eastern North America that is ecologically, culturally, and economically important.We report the first haplotype‐resolved chromosome‐scale genome assembly ofQ. albaand conduct comparative analyses of genome structure and gene content against other published Fagaceae genomes. We investigate the genetic diversity of this widespread species and the phylogenetic relationships among oaks using whole genome data.Despite strongly conserved chromosome synteny and genome size acrossQuercus, certain gene families have undergone rapid changes in size, including defense genes. Unbiased annotation of resistance (R) genes across oaks revealed that the overall number of R genes is similar across species – as are the chromosomal locations of R gene clusters – but, gene number within clusters is more labile. We found thatQ. albahas high genetic diversity, much of which predates its divergence from other oaks and likely impacts divergence time estimations. Our phylogenetic results highlight widespread phylogenetic discordance across the genus.The white oak genome represents a major new resource for studying genome diversity and evolution inQuercus. Additionally, we show that unbiased gene annotation is key to accurately assessing R gene evolution inQuercus. 

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2. Herbarium Specimens Provide Evidence for the Early Introduction of Erysiphe quercicola Into the United States and Document New Hosts

   https://doi.org/10.1111/efp.70072  

   Bradshaw, Michael; Paul, Andrew; Rennie, Elizabeth; Gilbert, Gregory S; Robeson, Senna; Donnelly, Ryan; Crouch, Uma; Mitchell, James; Braun, Uwe (April 2026, Forest Pathology)

   ABSTRACT The powdery mildew fungusErysiphe quercicola(Erysiphaceae) has a complex taxonomic history that has long complicated assessments of its geographic distribution and host associations. Although knowledge of the global host range of this species has expanded substantially over the past two decades, sequencing‐confirmed records from North America remain scarce, and despite its recognition as an introduced pathogen, the timing of introduction and the geographic extent and host range ofE. quercicolain the United States are poorly understood. In this study, herbarium specimens ofE. quercicolafrom North America, spanning both historical and contemporary collections, were examined using molecular phylogenetic approaches. Specimens collected from multipleQuercusspecies across several regions of the United States, as well as from related hosts within theFagaceae, were evaluated. Sequence data confirm the presence ofE. quercicolain North America onQuercusspecies based on herbarium specimens collected as early as 1944, as well as on mango (Mangifera indica;Anacardiaceae) in Florida from material collected in 1935. These records raise the possibility of historical introduction pathways associated with cultivated hosts, potentially from the horticulturally important mango tree (M. indica); however, additional multilocus phylogenetic analyses and host range inoculation experiments will be required to determine whether powdery mildew populations infecting mango andQuercusin North America represent the same lineage. Additional sequencing‐confirmed records document the species on multiple native oak species representing different sections ofQuercusincludingQ. bicolor,Q. gambelii,Q. garryana,Q. geminata,Q. kelloggii,Quercus × jolonensisandQ. macrocarpaas well as onNotholithocarpus densiflorus. Together, these findings clarify the long‐term presence ofE. quercicolain the United States, expand knowledge of its North American host range, and demonstrate the value of herbaria for reconstructing the invasion history of forest pathogens. 

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3. Quantum Q -Systems and Fermionic Sums—The Non-Simply Laced Case

   https://doi.org/10.1093/imrn/rnaa198  

   Simon Lin, Mingyan (August 2020, International Mathematics Research Notices)

   null (Ed.)

   Abstract In this paper, we seek to prove the equality of the $$q$$-graded fermionic sums conjectured by Hatayama et al. [ 14] in its full generality, by extending the results of Di Francesco and Kedem [ 9] to the non-simply laced case. To this end, we will derive explicit expressions for the quantum $$Q$$-system relations, which are quantum cluster mutations that correspond to the classical $$Q$$-system relations, and write the identity of the $$q$$-graded fermionic sums as a constant term identity. As an application, we will show that these quantum $$Q$$-system relations are consistent with the short exact sequence of the Feigin–Loktev fusion product of Kirillov–Reshetikhin modules obtained by Chari and Venkatesh [ 5]. 

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4. High overlap in the richness and composition of ectomycorrhizal fungal communities associated with Corylus shrubs and co-occurring Quercus and Pinus trees

   https://doi.org/10.1080/00275514.2024.2445110  

   Kennedy, Peter G; Nieves, Dyonishia J; Walther, Kelcie Paige; Matney, Soren; Ronold, Eivind K (March 2025, Mycologia)

   Despite being present in many North American forest understories, the ectomycorrhizal (ECM) fungal communities associated with Corylus shrubs have received no prior study. To address this knowledge gap, we characterized the ECM fungal communities on roots of Corylus shrubs as well as co-occurring Quercus and Pinus trees in Minnesota, USA. ECM-colonized root tips from pairs of Corylus shrubs and four ECM tree species, Quercus macrocarpa, Quercus ellipsoidalis, Pinus strobus, and Pinus resinosa, growing in close proximity (<1 m), were sampled at the Cedar Creek Ecosystem Science Reserve. ECM fungal communities were assessed using high-throughput sequencing of the ITS2 region. ECM fungal operational taxonomic unit (OTU) richness was equivalent among the two Quercus species and their associated Corylus shrubs, but significantly higher on P. strobus–associated Corylus shrubs compared with P. strobus, P. resinosa, and P. resinosa–associated Corylus shrubs. ECM fungal community composition on Corylus shrubs largely mirrored that on each of the Quercus and Pinus species, although the two Pinus commu- nities were significantly different from each other. Further, the same ECM fungal OTUs were commonly encountered on paired Corylus–tree host samples, suggesting a high potential for co- colonization by the same fungal individuals. Collectively, these results support the growing consensus that woody understory plants often associate with similar ECM fungal communities as co-occurring tree hosts regardless of phylogenetic relatedness 

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5. On quasi-reducibility for c.e. sets Part I. The structure of the Q -degrees and the sQ -degrees

   https://doi.org/10.1093/logcom/exaf076  

   Ben-Shahar, Sapir; Downey, Rodney G; Soskova, Mariya (January 2026, Journal of Logic and Computation)

   Abstract We study the structure of the c.e. $$Q$$- and $sQ$-degrees. For both structures, we show that there are join irreducible degrees but no Ahmad pairs. We show that the structures are not distributive, and that the lattice $$N_{5}$$ embeds in both structures. On the other hand the lattice $$M_{5}$$ cannot be embedded in the c.e. $sQ$-degrees, but a critical triple can be embedded. Finally, we show that no initial segment of the c.e. $sQ$-degrees or the c.e. $$Q$$-degrees is a lattice. 

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