Phylogenomic challenges in polyploid-rich lineages: Insights from paralog processing and reticulation methods using the complex genus Packera (Asteraceae: Senecioneae)
Authors: Moore-Pollard, E. R., Ellestad, P., Mandel, J.
The study examined how polyploidy, hybridization, and incomplete lineage sorting affect phylogenetic reconstructions in the genus Packera, evaluating several published paralog‑processing pipelines. Results showed that the choice of orthology and paralog handling methods markedly altered tree topology, time‑calibrated phylogenies, biogeographic histories, and detection of ancient reticulation, underscoring the need for careful methodological selection alongside comprehensive taxon sampling.
Arabidopsis lines with modified ascorbate concentrations reveal a link between ascorbate and auxin biosynthesis
Authors: Fenech, M., Zulian, V., Moya-Cuevas, J., Arnaud, D., Morilla, I., Smirnoff, N., Botella, M. A., Stepanova, A. N., Alonso, J. M., Martin-Pizarro, C., Amorim-Silva, V.
The study used Arabidopsis thaliana mutants with low (vtc2, vtc4) and high (vtc2/OE-VTC2) ascorbate levels to examine how ascorbate concentration affects gene expression and cellular homeostasis. Transcriptomic analysis revealed that altered ascorbate levels modulate defense and stress pathways, and that TAA1/TAR2‑mediated auxin biosynthesis is required for coping with elevated ascorbate in a light‑dependent manner.
Rapid population flux in bacterial spot xanthomonads during a transition in dominance between two genotypes in consecutive tomato production seasons and identification of a new species Xanthomonas oklahomensis sp. nov.
Authors: Johnson, B., Subedi, A., Damicone, J., Goss, E., Jones, J. B., Jibrin, M. O.
The study examined Xanthomonas strains causing bacterial spot on tomato in Oklahoma fields during 2018‑2019, revealing a shift from X. euvesicatoria pv. euvesicatoria (Xee) to X. euvesicatoria pv. perforans (Xep) race T4, which also expanded to pepper. Phenotypic assays and whole‑genome sequencing highlighted differences in race composition, host range, copper sensitivity, and effector repertoires, and identified a novel species, Xanthomonas oklahomensis.