EMBO Press is an editorially independent publishing platform for the development of EMBO scientific publications.

The plant phytohormone ethylene regulates numerous physiological processes and contributes to plant–microbe interactions. Plants induce ethylene production to ward off pathogens after recognition of conserved microbe-associated molecular patterns (MAMPs). However, plant immune responses against pathogens are essentially not different from those triggered by neutral and beneficial microbes. Recent studies indicate that ethylene is an important factor for beneficial plant–microbial association under abiotic stress such as salt and heat stress. The association of beneficial microbes with plants under abiotic stresses modulates ethylene levels which control the expression of ethylene-responsive genes (ERF), and ERFs further regulate the plant transcriptome, epi-transcriptome, Na⁺/K⁺ homeostasis and antioxidant defense mechanisms against reactive oxygen species (ROS). Understanding ethylene-dependent plant–microbe interactions is crucial for the development of new strategies aimed at enhancing plant tolerance to harsh environmental conditions. In this review, we underline the importance of ethylene in beneficial plant–microbe interaction under abiotic stresses.

Plant-microbiome interactions are crucial in shaping plant growth, stress resilience, and disease resistance. Among these, the seed microbiome plays a pivotal role in early plant development and ecological adaptation. However, little is known about the factors that determine the abundance and functions of the seed microbiome, as well as the role of the host genome in shaping the microbial diversity across different ecotypes. In this study, we investigated the diversity of the Arabidopsis seed microbiomes that originate from multiple geographical locations. High-throughput sequencing identified key bacterial taxa that govern Arabidopsis seed microbiota diversity. Distinct compositions of bacterial taxa were identified in Arabidopsis accessions sharing geographical location and similar soil features. Genome-wide association studies (GWAS) revealed that both the abundance of key taxa and common functional traits are associated with specific host genetic loci such as the RNA-binding protein RPB47B, mutants of which showed altered physiological properties related to soil properties and microbial diversity. Overall, our study establishes that geographical, soil and genetic host factors shape the Arabidopsis seed microbiome.

Oxalotrophy refers to the ability of bacteria to utilize oxalate as a carbon and energy source. This is a critical process with significant implications for the global carbon cycle. Oxalate-degrading bacteria play a key role in carbon sequestration through the oxalate-carbonate pathway (OCP), contributing to stable inorganic carbon pools. In this study, we identified and cataloged 20 enzymes associated with various facets of oxalate metabolism to characterize the oxalotrophic potential of bacteria. Within this group, sets of enzymes were grouped into two functional categories in the context of carbon sequestration: a biomineralization toolkit for converting oxalate to inorganic carbon and an assimilation toolkit for incorporating oxalate into metabolic pathways such as amino acid biosynthesis and energy production. Using bioinformatic approaches, we analyzed a collection of 536 bacterial genomes from desert and dryland strains spanning 81 genera to identify oxalotrophs. To validate our findings, we tested several bacterial strains for growth on media supplemented with exogenous oxalate. Notably, while multiple bacterial strains grew on oxalate media, two Pseudomonas species, namely JZ043 and JZ097, failed to grow despite genomic predictions suggesting otherwise. Further investigation of these strains revealed several non-conservative amino acid substitutions in the glyoxylate carboligase enzyme (EC 4.1.1.47), a key player in oxalate metabolism, suggesting a potential link between these mutations and their inability to metabolize oxalate. Our findings highlight the significance of our approach for identifying oxalotrophic bacteria (OxB) and offer valuable insights into the molecular basis of oxalate metabolism. Graphical

Heat stress severely affects plant growth, causing significant crop yield losses. To counteract this, plants employ adaptive strategies, including chromatin and transcriptional regulation of heat stress-related genes. However, the role of RNA methylation in heat stress response remains unclear. This study identifies m6A RNA methylation as a negative regulator of thermotolerance in Arabidopsis. Loss of m6A modification enhances resilience to heat stress by increasing transcript levels of heat-responsive genes and stabilizing their mRNAs. Upon heat shock, plants transiently reduce m6A levels by modulating key methylation machinery genes. This m6A deficiency enriches the H3K4me3 histone mark at heat-responsive gene loci, boosting their transcription. The combined effect of m6A-regulated chromatin changes and mRNA stability facilitates the accumulation of heat shock proteins essential for cellular protection and stress response. These findings reveal an interplay between m6A RNA methylation and histone modifications, forming a regulatory network that fine-tunes gene expression during heat stress. This novel mechanism highlights m6A as a critical regulator of plant thermotolerance, offering a promising target for improving heat stress resilience in crops.

Graphical Oxalotrophic bacteria from arid soils utilize oxalate via biomineralization (OCP) or assimilation pathways, influenced by key enzymes, shaping ecological roles and oxalate metabolism phenotypes in diverse genera.