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Salt tolerance is an important mechanism by which plants can adapt to a saline environment. To understand the process of salt tolerance, we performed global analyses of mRNA alternative polyadenylation (APA), an important regulatory mechanism during eukaryotic gene expression, in Arabidopsis thaliana and its halophytic relative Eutrema salsugineum with regard to their responses to salt stress. Analyses showed that while APA occurs commonly in both Arabidopsis and Eutrema , Eutrema possesses fewer APA genes than Arabidopsis (47% vs. 54%). However, the proportion of APA genes was significantly increased in Arabidopsis under salt stress but not in Eutrema . This indicated that Arabidopsis is more sensitive to salt stress and that Eutrema exhibits an innate response to such conditions. Both species utilized distal poly(A) sites under salt stress; however, only eight genes were found to overlap when their 3′ untranslated region (UTR) lengthen genes were compared, thus revealing their distinct responses to salt stress. In Arabidopsis , genes that use distal poly(A) sites were enriched in response to salt stress. However, in Eutrema , the use of poly(A) sites was less affected and fewer genes were enriched. The transcripts with upregulated poly(A) sites in Arabidopsis showed enriched pathways in plant hormone signal transduction, starch and sucrose metabolism, and fatty acid elongation; in Eutrema , biosynthetic pathways (stilbenoid, diarylheptanoid, and gingerol) and metabolic pathways (arginine and proline) showed enrichment. APA was associated with 42% and 29% of the differentially expressed genes (DE genes) in Arabidopsis and Eutrema experiencing salt stress, respectively. Salt specific poly(A) sites and salt-inducible APA events were identified in both species; notably, some salt tolerance-related genes and transcription factor genes exhibited differential APA patterns, such as CIPK21 and LEA4-5 . Our results suggest that adapted species exhibit more orderly response at the RNA maturation step under salt stress, while more salt-specific poly(A) sites were activated in Arabidopsis to cope with salinity conditions. Collectively, our findings not only highlight the importance of APA in the regulation of gene expression in response to salt stress, but also provide a new perspective on how salt-sensitive and salt-tolerant species perform differently under stress conditions through transcriptome diversity.

Background  Paris polyphylla Sm. is a precious medicinal plant rich in various active ingredients. In addition to the well-known saponins, the flavonoids it contains have unique pharmacological potential in antioxidant, neuroprotective, and metabolic regulation. However, the flavonoids in Paris polyphylla Sm. have not been fully researched and developed yet. In this work, we conducted a comprehensive metabolomics and transcriptomics analysis to reveal the metabolic differences and biosynthetic mechanisms of flavonoids in the leaves, stems, and roots of Paris polyphylla Sm. Results Non-targeted metabolomics analysis detected a total of 332 metabolites in Paris polyphylla Sm., among which flavonoids accounted for 19.49%. The diversity and abundance of flavonoids in leaves are the highest, followed by stems and roots. By comparing the metabolites of the roots, stems, and leaves in Paris polyphylla Sm., it was found that there were 45 differential metabolites (DMs) between the leaves and roots, of which flavonoids accounted for 35%. There are 38 DMs between leaves and stems, of which flavonoids account for 45.45%. And there are 52 DMs in stems and roots, among which flavonoids account for 25.53%. A total of 62,766 genes were detected by transcriptomics, and pairwise comparison showed that there were tens of thousands of differentially expressed genes (DEGs) between each group. Afterwards, we selected 39 flavonoids and related metabolites (e.g., kaempferol-3-O-glucoside, quercetin 3-β-D-glucoside, rutin) for targeted metabolomics validation and performed RT-qPCR validation on 29 key flavonoid synthesis genes (e.g., C4H, CHS, FLS, F3’H) to verify the reliability of non-targeted metabolomics and transcriptomics. Conclusions This work indicated that leaves are the main site for the biosynthesis of flavonoids in Paris polyphylla Sm. Among them, kaempferol-3-O-glucoside, quercetin 3-β-D-glucoside, rutin, and other flavonoids are present in higher contents in leaves ( P  < 0.05). Further research on its biosynthetic mechanism indicates that naringenin chalcone is converted to naringenin by chalcone isomerase (CHI). Among them, CHI may be the rate-limiting enzyme in the biosynthesis of flavonoids in Paris polyphylla Sm. The expression of FLS is higher in leaves ( P  < 0.05) and tends to promote the synthesis of flavonols. This work promotes the utilization of non-medicinal parts of Paris polyphylla Sm. and enhances the sustainable development of this precious traditional Chinese medicine resource.

In strawberries, fruit set is considered as the transition from the quiescent ovary to a rapidly growing fruit. Auxin, which is produced from the fertilized ovule in the achenes, plays a key role in promoting the enlargement of receptacles. However, detailed regulatory mechanisms for fruit set and the mutual regulation between achenes and receptacles are largely unknown. In this study, we found that pollination promoted fruit development (both achene and receptacle), which could be stimulated by exogenous auxin treatment. Interestingly, auxin was highly accumulated in achenes, but not in receptacles, after pollination. Further transcriptome analysis showed that only a small portion of the differentially expressed genes induced by pollination overlapped with those by exogenous auxin treatment. Auxin, but not pollination, was able to activate the expression of growth-related genes, especially in receptacles, which resulted in fast growth. Meanwhile, those genes involved in the pathways of other hormones, such as GA and cytokinin, were also regulated by exogenous auxin treatment, but not pollination. This suggested that pollination was not able to activate auxin responses in receptacles but produced auxin in fertilized achenes, and then auxin might be able to transport or transduce from achenes to receptacles and promote fast fruit growth at the early stage of fruit initiation. Our work revealed a potential coordination between achenes and receptacles during fruit set, and auxin might be a key coordinator.

Paralogous transcription factors (TFs) frequently recognize highly similar DNA motifs. Homodimerization can help distinguish them according to their different dimeric configurations. Here, by studying R2R3‐MYB TFs, we show that homodimerization can also directly change the recognized DNA motifs to distinguish between similar TFs. By high‐throughput SELEX, we profiled the specificity landscape for 40 R2R3‐MYBs of subfamily VIII and curated 833 motif models. The dimeric models show that homodimeric binding has evoked specificity changes for AtMYBs. Focusing on AtMYB2 as an example, we show that homodimerization has modified its specificity and allowed it to recognize additional cis‐regulatory sequences that are different from the closely related CCWAA‐box AtMYBs and are unique among all AtMYBs. Genomic sites described by the modified dimeric specificities of AtMYB2 are conserved in evolution and involved in AtMYB2‐specific transcriptional activation. Collectively, this study provides rich data on sequence preferences of VIII R2R3‐MYBs and suggests an alternative mechanism that guides closely related TFs to respective cis‐regulatory sites. Closely related transcription factor (TF) paralogs are facing the “specificity paradox”—they share similar binding motifs, but their cis‐regulatory targets and physiological roles can be different. By applying high‐throughput SELEX to 40 R2R3‐MYB TFs, this study currently generates the largest data set illustrating the homodimeric specificities of plant TFs, while also reveals a yet unrecognized mechanism to solve the “specificity paradox”—a TF's binding specificity can change drastically upon homodimerization, and become unique across the whole family. Highlights A homodimerization‐based mechanism enables eukaryotes to distinguish paralogous transcription factors. The largest plant SELEX data set illustrates the sequence preferences of 40 VIII R2R3‐MYBs. The high specificity AtMYBs were discovered and named CCWAA‐box.

Auxin is a crucial hormone that regulates various aspects of plant growth and development. It exerts its effects through multiple signaling pathways, including the TIR1/AFB-based transcriptional regulation in the nucleus. However, the specific role of auxin receptors in determining developmental features in the strawberry (Fragaria vesca) remains unclear. Our research has identified FveAFB5, a potential auxin receptor, as a key player in the development and auxin responses of woodland strawberry diploid variety Hawaii 4. FveAFB5 positively influences lateral root development, plant height, and fruit development, while negatively regulating shoot branching. Moreover, the mutation of FveAFB5 confers strong resistance to the auxinic herbicide picloram, compared to dicamba and quinclorac. Transcriptome analysis suggests that FveAFB5 may initiate auxin and abscisic acid signaling to inhibit growth in response to picloram. Therefore, FveAFB5 likely acts as an auxin receptor involved in regulating multiple processes related to strawberry growth and development.

A crucial step for mRNA polyadenylation is poly(A) signal recognition by trans-acting factors. The mammalian cleavage and polyadenylation specificity factor (CPSF) complex components CPSF30 and WD repeat-containing protein33 (WDR33) recognize the canonical AAUAAA for polyadenylation. In Arabidopsis (Arabidopsis thaliana), the flowering time regulator FY is the homolog of WDR33. However, its role in mRNA polyadenylation is poorly understood. Using poly(A) tag sequencing, we found that >50% of alternative polyadenylation (APA) events are altered in fy single mutants or double mutants with oxt6 (a null mutant of AtCPSF30), but mutation of the FY WD40-repeat has a stronger effect than deletion of the plant-unique Pro-Pro-Leu-Pro-Pro (PPLPP) domain. fy mutations disrupt AAUAAA or AAUAAA-like poly(A) signal recognition. Notably, A-rich signal usage is suppressed in the WD40-repeat mutation but promoted in PPLPP-domain deficiency. However, fy mutations do not aggravate the altered signal usage in oxt6. Furthermore, the WD40-repeat mutation shows a preference for 3′ untranslated region shortening, but the PPLPP-domain deficiency shows a preference for lengthening. Interestingly, the WD40-repeat mutant exhibits shortened primary roots and late flowering with alteration of APA of related genes. Importantly, the long transcripts of two APA genes affected in fy are related to abiotic stress responses. These results reveal a conserved and specific role of FY in mRNA polyadenylation.

Dimethylated histone H3 Lys9 (H3K9me2) is a conserved heterochromatic mark catalyzed by SUPPRESSOR OF VARIEGATION 3-9 HOMOLOG (SUVH) methyltransferases in plants. However, the mechanism underlying the locus specificity of SUVH enzymes has long been elusive. Here, we show that a conserved N-terminal motif is essential for SUVH6-mediated H3K9me2 deposition in planta. The SUVH6 N-terminal peptide can be recognized by the bromo-adjacent homology (BAH) domain of the RNA- and chromatin-binding protein ANTI-SILENCING 1 (ASI1), which has been shown to function in a complex to confer gene expression regulation. Structural data indicate that a classic aromatic cage of ASI1-BAH domain specifically recognizes an arginine residue of SUVH6 through extensive hydrogen bonding interactions. A classic aromatic cage of ASI1 specifically recognizes an arginine residue of SUVH6 through extensive cation-π interactions, playing a key role in recognition. The SUVH6-ASI1 module confers locus-specific H3K9me2 deposition at most SUVH6 target loci and gives rise to distinct regulation of gene expression depending on the target loci, either conferring transcriptional silencing or posttranscriptional processing of mRNA. More importantly, such mechanism is conserved in multiple plant species, indicating a coordinated evolutionary process between SUVH6 and ASI1. In summary, our findings uncover a conserved mechanism for the locus specificity of H3K9 methylation in planta. These findings provide mechanistic insights into the delicate regulation of H3K9 methylation homeostasis in plants.

In recent years, plant-derived exosome-like nanoparticles (PELNs) have attracted extensive attention. Among them, Ginger-derived exosome-like nanoparticles (GELNs) represent the most extensively studied category, demonstrating a wide spectrum of pharmacological activities. However, their specific efficacy against lung cancer remains largely unexplored and warrants further investigation. The appropriate isolation of GELNs is fundamental to all related research, yet a systematic comparison of different extraction methods is currently lacking. This study aimed to evaluate the differences among GELNs extracted by various methods and to investigate their anti-lung cancer pharmacological activities. The study employed four common isolation methods-ultracentrifugation (UC), sucrose gradient UC (sgUC), membrane filtration, and polyethylene glycol-based precipitation (PEG-based precipitation) - to isolate GELNs. The GELNs were characterized by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and zeta potential measurements. Stability was evaluated under various conditions, including saline, serum, and different storage temperatures. The compositional profiles of GELNs extracted by four methods were explored using non-targeted metabolomics. A549 cells and PC-9 cells were used to assess the cellular uptake and anti-lung cancer efficacy of the four GELNs types. Network pharmacology, molecular docking, and molecular dynamics simulations were integrated to elucidate the potential mechanisms underlying their anti-lung cancer effects. The four methods successfully isolated GELNs with distinct profiles: UC achieved the highest protein yield (1.630 ± 0.022 g/kg), membrane filtration yielded the highest particle concentration (46.9 ± 6.71×10 particles/mL) but the lowest protein yield (0.059 ± 0.002 g/kg). Stability studies indicated that the highest stability of GELNs was observed for those isolated by UC and sgUC in both 0.9% and 10% NaCl. Furthermore, GELNs prepared by UC and membrane filtration showed excellent stability in serum. It was also demonstrated that -80°C provided the optimal storage condition for GELNs. Non-targeted metabolomics revealed the presence of 649 shared metabolites among the GELNs extracted by the four methods, along with method-specific unique metabolites. GELNs extracted by all four methods were internalized by both A549 and PC-9 cells. Among them, UC-isolated GELNs demonstrated the most potent anti-proliferative activity against the lung cancer cells. Through network pharmacology, 21 key targets of UC-isolated GELNs against lung cancer were identified. Molecular docking and molecular dynamics simulations further verified that 10-Gingerol, Hexahydrocurcumin, and [6]-Dehydrogingerdione from GELNs could stably bind to key targets, including Glycogen Synthase Kinase-3β (GSK3B), Progesterone Receptor (PGR), and SRC Proto-Oncogene, Non-Receptor Tyrosine Kinase (SRC). This study demonstrates that although all four methods can isolate GELNs, UC is recommended for fundamental research due to its high protein yield, excellent stability, and potent in vitro anti-lung cancer activity. Furthermore, the anti-lung cancer activity of GELNs may be attributed to the regulation of GSK3B, PGR, and SRC by 10-Gingerol, Hexahydrocurcumin, and [6]-Dehydrogingerdione.

• Despite a much higher proportion of intragenic heterochromatin-containing genes in crop genomes, the importance of intragenic heterochromatin in crop development remains unclear. Intragenic heterochromatin can be recognised by a protein complex, ASI1–AIPP1–EDM2 (AAE) complex, to regulate alternative polyadenylation. • Here, we investigated the impact of rice ASI1 on global poly(A) site usage through poly(A) sequencing and ASI1-dependent regulation on rice development. • We found that OsASI1 is essential for rice pollen development and flowering. OsASI1 dysfunction has an important impact on global poly(A) site usage, which is closely related to heterochromatin marks. Intriguingly, OsASI1 interacts with the intronic heterochromatin of OsXRNL, a nuclear XRN family exonuclease gene involved in the processing of an miRNA precursor, to promote the processing of full-length OsXRNL and regulate miRNA abundance. We found that OsASI1-mediated regulation of pollen development partially depends on OsXRNL. Finally, we characterised the rice AAE complex and its involvement in alternative polyadenylation and pollen development. • Our findings help to elucidate an epigenetic mechanism governing miRNA abundance and rice development, and provide a valuable resource for studying the epigenetic mechanisms of many important processes in crops.

A crucial step for mRNA polyadenylation is poly(A) signal recognition by trans-acting factors. The mammalian cleavage and polyadenylation specificity factor (CPSF) complex components CPSF30 and WD repeat-containing protein33 (WDR33) recognize the canonical AAUAAA for polyadenylation. In Arabidopsis (Arabidopsis thaliana), the flowering time regulator FY is the homolog of WDR33. However, its role in mRNA polyadenylation is poorly understood. Using poly(A) tag sequencing, we found that >50% of alternative polyadenylation (APA) events are altered in fy single mutants or double mutants with oxt6 (a null mutant of AtCPSF30), but mutation of the FY WD40-repeat has a stronger effect than deletion of the plant-unique Pro-Pro-Leu-Pro-Pro (PPLPP) domain. fy mutations disrupt AAUAAA or AAUAAA-like poly(A) signal recognition. Notably, A-rich signal usage is suppressed in the WD40-repeat mutation but promoted in PPLPP-domain deficiency. However, fy mutations do not aggravate the altered signal usage in oxt6. Furthermore, the WD40-repeat mutation shows a preference for 3' untranslated region shortening, but the PPLPP-domain deficiency shows a preference for lengthening. Interestingly, the WD40-repeat mutant exhibits shortened primary roots and late flowering with alteration of APA of related genes. Importantly, the long transcripts of two APA genes affected in fy are related to abiotic stress responses. These results reveal a conserved and specific role of FY in mRNA polyadenylation.