Background: The R2R3-MYB transcription factor is one of the largest gene families in plants and involved in the regulation of plant development, hormone signal transduction, biotic and abiotic stresses. Tobacco is one of the most important model plants. Therefore, it will be of great significance to investigate the R2R3-MYB gene family and their expression patterns under abiotic stress and senescence in tobacco. Results: A total of 174 R2R3-MYB genes were identified from tobacco (Nicotiana tabacum L.) genome and were divided into 24 subgroups based on phylogenetic analysis. Gene structure (exon/intron) and protein motifs were especially conserved among the NtR2R3-MYB genes, especially members within the same subgroup. The NtR2R3-MYB genes were distributed on 24 tobacco chromosomes. Analysis of gene duplication events obtained 3 pairs of tandem duplication genes and 62 pairs of segmental duplication genes, suggesting that segmental duplications is the major pattern for R2R3-MYB gene family expansion in tobacco. Cis-regulatory elements of the NtR2R3-MYB promoters were involved in cellular development, phytohormones, environmental stress and photoresponsive. Expression profile analysis showed that NtR2R3-MYB genes were widely expressed in different maturity tobacco leaves, and however, the expression patterns of different members appeared to be diverse. The qRT-PCR analysis of 15 NtR2R3-MYBs confirmed their differential expression under different abiotic stresses (cold, salt and drought), and notably, NtMYB46 was significantly up-regulated under three treatments. Conclusions: In summary, a genome-wide identification, evolutionary and expression analysis of R2R3-MYB gene family in tobacco were conducted. Our results provided a solid foundation for further biological functional study of NtR2R3-MYB genes in tobacco.

High-density genetic maps can significantly improve the resolution of QTL mapping. We constructed a high-density recombination bin-based genetic map of eggplant based on 200 F₂ plants from an interspecific cross (Solanum melongena × S. incanum) using the whole genome resequencing strategy. The map was 2022.8 cM long, covering near 99% of the eggplant genome. The map contained 3776 bins, with 3644 (96.5%) being effective (position non-redundant) ones, giving a nominal average distance of 0.54 cM and an effective average distance of 0.56 cM between adjacent bins, respectively. Using this map and 172 F_2:3 lines, a major QTL with pleiotropic effects on two anthocyanin pigmentation-related traits, leaf vein color (LVC) and fruit pericarp color (FPC), was steadily detected in a bin interval of 2.28 cM (or 1.68 Mb) on chromosome E10 in two cropping seasons, explaining ~65% and 55% of the phenotypic variation in LVC and FPC, respectively. Genome-wide association analysis in this population validated the QTL and demonstrated the correctness of mapping two bins of chromosome E02 onto E10. Bioinformatics analysis suggested that a WDR protein gene inside the bin interval with reliable effective variation between the two parents could be a possible candidate gene of the QTL.

Class III peroxidases (PRXs) are plant-specific enzymes and play important roles in plant growth, development and stress response. In this study, a total of 102 non-redundantPRXgene members (StPRXs) were identified in potato (Solanum tuberosumL.). They were divided into 9 subfamilies based on phylogenetic analysis. The members of each subfamily were found to contain similar organizations of the exon/intron structures and protein motifs. TheStPRXgenes were not equally distributed among chromosomes. There were 57 gene pairs of segmental duplication and 26 gene pairs of tandem duplication. Expression pattern analysis based on the RNA-seq data of potato from public databases indicated thatStPRXgenes were expressed differently in various tissues and responded specifically to heat, salt and drought stresses. Most of theStPRXgenes were expressed at significantly higher levels in root than in other tissues. In addition, real-time quantitative PCR (qRT-PCR) analysis for 7 selectedStPRXgenes indicated that these genes displayed various expression levels under abiotic stresses. Our results provide valuable information for better understanding the evolution ofStPRXgene family in potato and lay the vital foundation for further exploration ofPRXgene function in plants.

Tobacco (Nicotiana tabacum L.) is a globally crop due to its distinctive flavor and economic value. In this study, we systematically analyzed the dynamic changes in volatile substances, broad-spectrum metabolites, enzymes, and biochemical compounds in tobacco leaves during flue-curing process. Combining metabolomics with enzyme activity and biochemical analysis, we identified that 43℃ is a critical period for enzyme activity and metabolite transitions, while 45 ℃ requires stringent moisture control. During the T3 stages, phenolic acids, amino acids, and derivatives were notably enriched, with increases of 19.58-fold, 18.59-fold, and 17.33-fold in lmmn001643, MWS20633g, and Lmhn004756, respectively. These compounds may serve as candidate biomarkers for non-volatile compounds. Aroma dynamics primarily contributed to the green and sweet flavor of flue-cured tobacco leaves, and the key aroma components included D114, KMW1317, and KMW0466. Differential volatile and non-volatile metabolites were enriched in four pathways, including monoterpenoid biosynthesis, tyrosine metabolism, phenylalanine metabolism, and phenylpropanoid biosynthesis. These pathways are closely related to phenylalanine ammonia-lyase and the synthesis of chlorogenic acid and rutin, which influence the aroma quality, aroma intensity, irritation, and volatility of tobacco. Additionally, the contents of caffeic acid, ferulic acid, sinapic acid, and PAL activity in phenylpropanoid biosynthesis pathway, increased with the rising temperature, accelerating reactions with alcohols and leading to increase lignin formation. This study enhances our understanding of the dynamic changes in the aroma and metabolic substances of Cuibi 1(CB-1) at the critical stages of the curing process and offers valuable insights for process improvement.

Background: The dirigent (DIR) genes encode proteins that act as crucial regulators of plant lignin biosynthesis. In Solanaceae species, members of the DIR gene family are intricately related to plant growth and development, playing a key role in responding to various biotic and abiotic stresses. It will be of great application significance to analyze the DIR gene family and expression profile under various pathogen stresses in Solanaceae species. Results: A total of 57 tobacco NtDIRs and 33 potato StDIRs were identified based on their respective genome sequences. Phylogenetic analysis of DIR genes in tobacco, potato, eggplant and Arabidopsis thaliana revealed three distinct subgroups (DIR-a, DIR-b/d and DIR-e). Gene structure and conserved motif analysis showed that a high degree of conservation in both exon/intron organization and protein motifs among tobacco and potato DIR genes, especially within members of the same subfamily. Total 8 pairs of tandem duplication genes (3 pairs in tobacco, 5 pairs in potato) and 13 pairs of segmental duplication genes (6 pairs in tobacco, 7 pairs in potato) were identified based on the analysis of gene duplication events. Cis-regulatory elements of the DIR promoters participated in hormone response, stress responses, circadian control, endosperm expression, and meristem expression. Transcriptomic data analysis under biotic stress revealed diverse response patterns among DIR gene family members to pathogens, indicating their functional divergence. After 96 h post-inoculation with Ralstonia solanacearum L. (Ras), tobacco seedlings exhibited typical symptoms of tobacco bacterial wilt. The qRT-PCR analysis of 11 selected NtDIR genes displayed differential expression pattern in response to the bacterial pathogen Ras infection. Using line 392278 of potato as material, typical symptoms of potato late blight manifested on the seedling leaves under Phytophthora infestans infection. The qRT-PCR analysis of 5 selected StDIR genes showed up-regulation in response to pathogen infection. Notably, three clustered genes (NtDIR2, NtDIR4, StDIR3) exhibited a robust response to pathogen infection, highlighting their essential roles in disease resistance. Conclusion: The genome-wide identification, evolutionary analysis, and expression profiling of DIR genes in response to various pathogen infection in tobacco and potato have provided valuable insights into the roles of these genes under various stress conditions. Our results could provide a basis for further functional analysis of the DIR gene family under pathogen infection conditions.

Optimizing fermentation duration is critical for producing high-quality cigar tobacco leaves This study examines changes in microorganisms and metabolites during CTL fermentation at four time points: 0 days (T0), 25 days (T1), 50 days (T2), and 75 days (T3). We observed a decreasing trend in total soluble sugars, starch, total nitrogen, and nicotine levels as fermentation progressed. Notably, chemical components stabilized after T2 stages. The microbial community showed dynamic fluctuations, with alpha diversity indices (Shannon, ACE, Pielou’s evenness, and Chao-2) reaching equilibrium at T2 and maintaining stability thereafter. Dominant genera such as Staphylococcus , Aspergillus , Sphingomonas , and Penicillium persisted throughout the fermentation process. A total of 1801 metabolites were identified, with 584 showing differential expression across the fermentation periods. Notably, comparisons between T0 and T1, T2, and T3 revealed 218, 377, and 419 differentially expressed metabolites, respectively. KEGG enrichment analysis identified 28 co-existing metabolic pathways, seven of which are linked to cigar quality formation. Furthermore, 29 out of 47 differential metabolites significantly correlated with the eight dominant microbial genera. These findings indicate that the T2 stage achieves optimal balance between microbial activity and metabolite stabilization, providing a scientific basis for industrial process optimization.