Lorenzo, Z. C. | bioRxiv Science

bioRxiv2026

Pseudomonas volatiles shape the root transcriptome and microbiome to promote plant growth under drought

O_LIVolatile organic compounds (VOCs) emitted by soil bacteria influence interactions with other soil microbes and with plant roots. While their potential as plant-growth promoters is well recognized, their role in promoting plant resilience to abiotic stress and the underlying molecular mechanisms remains poorly understood. Here, we investigate the role of Pseudomonas VOCs in enhancing plant resilience to drought stress. C_LIO_LIArabidopsis thaliana plants were exposed to VOCs emitted by Pseudomonas strains under both control and osmotic-stress conditions. VOC exposure generally enhanced plant growth, and this effect was even more pronounced under both drought and salt stress. Transcriptomic analysis revealed that VOC exposure modulates key stress-responsive pathways, including those related to abscisic acid biosynthesis and signalling, sugar transport, iron uptake, aliphatic glucosinolate biosynthesis, and plant defences. Using Arabidopsis mutants, we identified abscisic acid and aliphatic glucosinolates as important components in mediating the plant response to VOCs. SWEET11/12 sugar transporters and ABA signaling genes were downregulated by VOCs exposure, in order to allow for a positive regulation of lateral root numbers (in case of SWEET genes) and plant growth in general under drought stress. In summary, using metabolomics, transcriptomics and functional analysis, we showed a negative cross-talk between the effects of VOCs on plant growth and glucosinolate production, whereas a positive interaction was observed between the biosynthesis of coumarins and VOCs. C_LIO_LINotably, VOCs also improved drought tolerance in soil-grown Brassica oleracea plants. We showed that VOC treatment altered the root-associated microbiome under drought, leading to a community composition more similar to that of well-watered plants. C_LIO_LIOur results show that Pseudomonas emitted VOCs can promote plant growth under drought conditions, linked to root transcriptional reprogramming and direct or indirect microbiome modulation. C_LI

plant biology↗

bioRxiv2025

Comparative regulomics provides novel insight into the evolution of wood formation across dicot and conifer trees

Understanding the regulatory program underlying wood formation is key to improving biomass production and carbon sequestration in trees. However, how wood formation evolved and how these programs have been rewired across lineages remains unclear. Here, we present the first high-spatial-resolution evo-devo resource spanning the wood transcriptomes of six tree species - three dicots and three conifers - capturing 250 million years of evolutionary divergence. Using orthology-aware co-expression network analysis, we identified genes with conserved and lineage-specific expression patterns. By integrating chromatin accessibility data and transcription factor motif analysis, we further inferred regulatory networks for xylem differentiation and secondary cell wall formation. We demonstrate how this dataset can be used to answer long standing questions in wood biology related to differences in acetylation of cell wall polymers and master regulators of xylem specification across dicot and conifer tree species. The data offer a foundational resource for the tree biology and evo-devo communities, and are publicly available at PlantGenIE.org.

genomics↗