Brassinosteroid-related genes are involved in regulating plant growth and stress responses. However, systematic analysis is limited to Gramineae species, and their roles in plant architecture and salt stress remain unclear. In this study, we identified brassinosteroid-related genes in wheat, barley, maize, and sorghum and investigated their evolutionary relationships, conserved domains, transmembrane topologies, promoter sequences, syntenic relationships, and gene/protein structures. Gene and genome duplications led to considerable differences in gene numbers. Specific domains were revealed in several genes (i.e., HvSPY, HvSMOS1, and ZmLIC), indicating diverse functions. Protein-protein interactions suggested their synergistic functions. Their expression profiles were investigated in wheat and maize, which indicated involvement in adaptation to stress and regulation of plant architecture. Several candidate genes for plant architecture (ZmBZR1 and TaGSK1/2/3/4-3D) and salinity resistance (TaMADS22/47/55-4B, TaGRAS19-4B, and TaBRD1-2A.1) were identified. This study is the first to comprehensively investigate brassinosteroid-related plant architecture genes in four Gramineae species and should help elucidate the biological roles of brassinosteroid-related genes in crops.

B-box (BBX) genes play important roles in plant growth regulation and responses to abiotic stresses. The plant growth and yield production of allotetraploid rapeseed is usually hindered by diverse nutrient stresses. However, no systematic analysis of Brassicaceae BBXs and the roles of BBXs in the regulation of nutrient stress responses have not been identified and characterized previously. In this study, a total of 536 BBXs were identified from nine brassicaceae species, including 32 AtBBXs, 66 BnaBBXs, 41 BoBBXs, 43 BrBBXs, 26 CrBBXs, 81 CsBBXs, 52 BnBBXs, 93 BjBBXs, and 102 BcBBXs. Syntenic analysis showed that great differences in the gene number of Brassicaceae BBXs might be caused by genome duplication. The BBXs were respectively divided into five subclasses according to their phylogenetic relationships and conserved domains, indicating their diversified functions. Promoter cis-element analysis showed that BBXs probably participated in diverse stress responses. Protein-protein interactions between BnaBBXs indicated their functions in flower induction. The expression profiles of BnaBBXs were investigated in rapeseed plants under boron deficiency, boron toxicity, nitrate limitation, phosphate shortage, potassium starvation, ammonium excess, cadmium toxicity, and salt stress conditions using RNA-seq data. The results showed that different BnaBBXs showed differential transcriptional responses to nutrient stresses, and some of them were simultaneously responsive to diverse nutrient stresses. Taken together, the findings investigated in this study provided rich resources for studying Brassicaceae BBX gene family and enriched potential clues in the genetic improvement of crop stress resistance.

Background: Histone modification is an important epigenetic regulatory mechanism and essential for stress adaptation in plants. However, systematic analysis of histone modification genes (HMs) in Brassicaceae species is lacking, and their roles in response to abiotic stress have not yet been identified. Results: In this study, we identified 102 AtHMs, 280 BnaHMs, 251 BcHMs, 251 BjHMs, 144 BnHMs, 155 BoHMs, 137 BrHMs, 122 CrHMs, and 356 CsHMs in nine Brassicaceae species, respectively. Their chromosomal locations, protein/gene structures, phylogenetic trees, and syntenies were determined. Specific domains were identified in several Brassicaceae HMs, indicating an association with diverse functions. Syntenic analysis showed that the expansion of Brassicaceae HMs may be due to segmental and whole-genome duplications. Nine key BnaHMs in allotetraploid rapeseed may be responsible for ammonium, salt, boron, cadmium, nitrate, and potassium stress based on co-expression network analysis. According to weighted gene co-expression network analysis (WGCNA), 12 BnaHMs were associated with stress adaptation. Among the above genes, BnaPRMT11 simultaneously responded to four different stresses based on differential expression analysis, while BnaSDG46, BnaHDT10, and BnaHDA1 participated in five stresses. BnaSDG46 was also involved in four different stresses based on WGCNA, while BnaSDG10 and BnaJMJ58 were differentially expressed in response to six different stresses. In summary, six candidate genes for stress resistance (BnaPRMT11, BnaSDG46, BnaSDG10, BnaJMJ58, BnaHDT10, and BnaHDA1) were identified. Conclusions: Taken together, these findings help clarify the biological roles of Brassicaceae HMs. The identified candidate genes provide an important reference for the potential development of stress-tolerant oilseed plants.

Phytohormone-related transcription factors (TFs) are involved in regulating stress responses and plant growth. However, systematic analysis of these TFs in Brassicaceae is limited, and their functions in stress adaptation and plant height (PH) regulation remain unclear. In this study, 2115 hormone-related TFs were identified in nine Brassicaceae species. Specific domains were found in several Brassicaceae hormone-related TFs, which may be associated with diverse functions. Syntenic analysis indicated that expansion of these genes was mainly caused by segmental duplication, with whole-genome duplication occurring in some species. Differential expression analysis and gene co-expression network analysis identified seven phytohormone-related TFs (BnaWRKY7, 21, 32, 38, 52, BnaGL3-4, and BnaAREB2-5) as possible key genes for cadmium (Cd) toxicity, salinity stress, and potassium (K) and nitrogen (N) deficiencies. Furthermore, BnaWRKY42 and BnaARR21 may play essential roles in plant height. Weighted gene co-expression network analysis (WGCNA) identified 15 phytohormone-related TFs and their potential target genes regulating stress adaptation and plant height. Among the above genes, BnaWRKY56 and BnaWRKY60 responded to four different stresses simultaneously, and BnaWRKY42 was identified in two dwarf rapeseeds. In summary, several candidate genes for stress resistance (BnaWRKY56 and BnaWRKY60) and plant height (BnaWRKY42) were identified. These findings should help elucidate the biological roles of Brassicaceae hormone-related TFs, and the identified candidate genes should provide a genetic resource for the potential development of stress-tolerant and dwarf oilseed plants.

Introduction: Plant-associated microbiota critically modulates host growth and environmental adaptation, yet assembly mechanisms, niche differentiation, and ecological strategies of bacterial communities inhabiting tobacco microhabitats remain poorly elucidated across geographical gradients. Methods: Here, we systematically characterized bacterial microbiome assembly across five tobacco-associated niches (bulk soil, rhizosphere soil, root, stem, and leaf) from seven typical tobacco-planting regions using 16S rRNA amplicon sequencing, genome annotation, and niche breadth analysis. The independent and interactive effects of geographical location and host compartment on community structure, and further compared genomic traits, functional profiles, and life-history strategies between specialist and generalist bacterial populations were quantified. Results: The results revealed a deterministic soil–plant continuum stratification of bacterial communities and diversity, with progressively simplified communities and decreasing alpha diversity from bulk soil to above-ground tissues, accompanied by progressive dominance of Proteobacteria . Geographical factors predominantly structured soil microbial communities via divergent edaphic properties, while host filtering acted as a universal dominant driver shaping endophytic microbiome assembly. Niche differentiation analysis demonstrated that niche-specialized bacterial ASVs overwhelmingly dominated all microhabitats and geographical sites, whereas generalist taxa only constituted auxiliary populations. Although specialist and generalist microbes exhibited highly conserved core genomic architectures and overall functional repertoires, they displayed distinct niche-specific functional divergence in metabolic pathways, stress resistance, and secondary metabolism across host compartments. Life-history strategy analysis further revealed that Y-strategist represented the core adaptive bacterial population, especially enriched in above-ground tobacco tissues. Discussion: Our study establishes a hierarchical dual-filtering assembly model for tobacco microbiota, clarifies the ecological differentiation and functional adaptation of specialist and generalist bacteria, and provides fundamental insights into the assembly rules and adaptive mechanisms of crop-associated microbiomes for future microbial resource utilization and agricultural microbiome regulation.