JANUS, a spliceosome-associated protein, promotes miRNA biogenesis in Arabidopsis.

MicroRNAs (miRNAs) are important regulators of genes expression. Their levels are precisely controlled through modulating the activity of the microprocesser complex (MC). Here, we report that JANUS, a homology of the conserved U2 snRNP assembly factor in yeast and human, is required for miRNA accumulation. JANUS associates with MC components Dicer-like 1 (DCL1) and SERRATE (SE) and directly binds the stem-loop of pri-miRNAs. In a hypomorphic janus mutant, the activity of DCL1, the numbers of MC, and the interaction of primary miRNA transcript (pri-miRNAs) with MC are reduced. These data suggest that JANUS promotes the assembly and activity of MC through its interaction with MC and/or pri-miRNAs. In addition, JANUS modulates the transcription of some pri-miRNAs as it binds the promoter of pri-miRNAs and facilitates Pol II occupancy of at their promoters. Moreover, global splicing defects are detected in janus. Taken together, our study reveals a novel role of a conserved splicing factor in miRNA biogenesis.

A DE1 BINDING FACTOR 1-GLABRA2 module regulates rhamnogalacturonan I biosynthesis in Arabidopsis seed coat mucilage.

The mucilage surrounding hydrated Arabidopsis thaliana seeds is a specialized extracellular matrix composed mainly of the pectic polysaccharide rhamnogalacturonan I (RG-I). Although, several genes responsible for RG-I biosynthesis have been identified, the transcriptional regulatory mechanisms controlling RG-I production remain largely unknown. Here we report that the trihelix transcription factor DE1 BINDING FACTOR 1 (DF1) is a key regulator of mucilage RG-I biosynthesis. RG-I biosynthesis is significantly reduced in loss-of-function mutants of DF1. DF1 physically interacts with GLABRA2 (GL2) and both proteins transcriptionally regulate the expression of the RG-I biosynthesis genes MUCILAGE MODIFIED 4 (MUM4) and GALACTURONOSYLTRANSFERASE-LIKE5 (GATL5). Through chromatin immunoprecipitation-quantitative PCR and transcriptional activation assays, we uncover a cooperative mechanism of the DF1-GL2 module in activating MUM4 and GATL5 expression, in which DF1 binds to the promoters of MUM4 and GATL5 through interacting with GL2 and facilitates the transcriptional activity of GL2. The expression of DF1 and GL2 is directly regulated by TRANSPARENT TESTA GLABRA2 (TTG2) and, in turn, DF1 directly represses the expression of TTG2. Taken together, our data reveal that the transcriptional regulation of mucilage RG-I biosynthesis involves a regulatory module, comprising DF1, GL2, and TTG2.

Ubiquitinated DA1 negatively regulates vascular cambium activity through modulating the stability of WOX4 in Populus.

Activity of the vascular cambium gives rise to secondary xylem for wood formation in trees. The transcription factor WUSCHEL-related HOMEOBOX4 (WOX4) is a central regulator downstream of the hormone and peptide signaling pathways that maintain cambial activity. However, the genetic regulatory network underlying WOX4-mediated wood formation at the post-transcriptional level remains to be elucidated. In this study, we identified the ubiquitin receptor PagDA1 in hybrid poplar (Populus alba × Populus glandulosa clone 84K) as a negative regulator of wood formation, which restricts cambial activity during secondary growth. Overexpression of PagDA1 in poplar resulted in a relatively reduced xylem due to decreased cambial cell division. By contrast, mutation of PagDA1 by CRISPR/Cas9 resulted in an increased cambial cell activity and promoted xylem formation. Genetic analysis demonstrated that PagDA1 functions antagonistically in a common pathway as PagWOX4 to regulate cambial activity. We propose that PagDA1 physically associates with PagWOX4 and modulates the degradation of PagWOX4 by the 26S proteasome. Moreover, genetic analysis revealed that PagDA1 exerts its negative effect on cambial development by modulating the stability of PagWOX4 in a ubiquitin-dependent manner mediated by the E3 ubiquitin ligase PagDA2. In sum, we have identified a cambial regulatory protein complex, PagDA1-PagWOX4, as a potential target for wood biomass improvement.

Two-Dimensional Transition Metal Phosphides As Cathode Additive in Robust Lithium-Sulfur Batteries.

The development of advanced cathode materials able to promote the sluggish redox kinetics of polysulfides is crucial to bringing lithium-sulfur batteries to the market. Herein, two electrode materials: namely, Zr2PS2 and Zr2PTe2, are identified through screening several hundred thousand compositions in the Inorganic Crystal Structure Database. First-principles calculations are performed on these two materials. These structures are similar to that of the classical MXenes. Concurrently, calculations show that Zr2PS2 and Zr2PTe2 possess high electrical conductivity, promote Li ion diffusion, and have excellent electrocatalytic activity for the Li-S reaction and particularly for the Li2S decomposition. Besides, the mechanisms behind the excellent predicted performance of Zr2PS2 and Zr2PTe2 are elucidated through electron localization function, charge density difference, and localized orbital locator. This work not only identifies two candidate sulfur cathode additives but may also serve as a reference for the identification of additional electrode materials in new generations of batteries, particularly in sulfur cathodes.

RNA-binding protein MAC5A interacts with the 26S proteasome to regulate DNA damage response in Arabidopsis.

DNA damage response (DDR) in eukaryotes is essential for the maintenance of genome integrity in challenging environments. The regulatory mechanisms of DDR have been well-established in yeast and humans. However, increasing evidence supports the idea that plants seem to employ different signaling pathways that remain largely unknown. Here, we report the role of MODIFIER OF SNC1, 4-ASSOCIATED COMPLEX SUBUNIT 5A (MAC5A) in DDR in Arabidopsis (Arabidopsis thaliana). Lack of MAC5A in mac5a mutants causes hypersensitive phenotypes to methyl methanesulfonate (MMS), a DNA damage inducer. Consistent with this observation, MAC5A can regulate alternative splicing of DDR genes to maintain the proper response to genotoxic stress. Interestingly, MAC5A interacts with the 26S proteasome (26SP) and is required for its proteasome activity. MAC core subunits are also involved in MMS-induced DDR. Moreover, we find that MAC5A, the MAC core subunits, and 26SP may act collaboratively to mediate high-boron-induced growth repression through DDR. Collectively, our findings uncover the crucial role of MAC in MMS-induced DDR in orchestrating growth and stress adaptation in plants.

Highly efficient and stable near-infrared photodetectors enabled from passivated tin-lead hybrid perovskites.

Tin-lead perovskite-based photodetectors have a wide light-absorption wavelength range, which spans 1000 nm. However, the preparation of the mixed tin-lead perovskite films faces two great obstacles, namely easy oxidation of Sn2+to Sn4+and fast crystallization from tin-lead perovskite precursor solutions, thus further resulting in poor morphology and high density of defects in tin-lead perovskite films. In this study, we demonstrated a high-performance of near-infrared photodetectors prepared from a stable low-bandgap (MAPbI3)0.5(FASnI3)0.5film modified with 2-fluorophenethylammonium iodide (2-F-PEAI). The addition engineering can efficiently improve the crystallization of (MAPbI3)0.5(FASnI3)0.5films through the coordination binding between Pb2+and N atom in 2-F-PEAI, and resulting in a uniform and dense (MAPbI3)0.5(FASnI3)0.5film. Moreover, 2-F-PEAI suppressed Sn2+oxidation and effectively passivated defects in the (MAPbI3)0.5(FASnI3)0.5film, thereby significantly reducing the dark current in the PDs. Consequently, the near-infrared photodetectors showed a high responsivity with a specific detectivity of over 1012Jones at 800 to near-1000 nm. Additionally, the stability of PDs incorporated with 2-F-PEAI has been significantly improved under air conditions, and the device with the 2-F-PEAI ratio of 400:1 retained 80% of its initial efficiency after 450 h storage in air without encapsulation. Finally, 5 × 5 cm2photodetector arrays were fabricated to demonstrate the potential utility of the Sn-Pb perovskite photodetector in optical imaging and optoelectronic applications.

MAC5, an RNA-binding protein, protects pri-miRNAs from SERRATE-dependent exoribonuclease activities.

MAC5 is a component of the conserved MOS4-associated complex. It plays critical roles in development and immunity. Here we report that MAC5 is required for microRNA (miRNA) biogenesis. MAC5 interacts with Serrate (SE), which is a core component of the microprocessor that processes primary miRNA transcripts (pri-miRNAs) into miRNAs and binds the stem-loop region of pri-miRNAs. MAC5 is essential for both the efficient processing and the stability of pri-miRNAs. Interestingly, the reduction of pri-miRNA levels in mac5 is partially caused by XRN2/XRN3, the nuclear-localized 5'-to-3' exoribonucleases, and depends on SE. These results reveal that MAC5 plays a dual role in promoting pri-miRNA processing and stability through its interaction with SE and/or pri-miRNAs. This study also uncovers that pri-miRNAs need to be protected from nuclear RNA decay machinery, which is connected to the microprocessor.

Free Nitrous Acid Inhibits Atenolol Removal during the Sidestream Partial Nitritation Process through Regulating Microbial-Induced Metabolic Types.

Limited studies have attempted to evaluate pharmaceutical removal during the sidestream partial nitritation (PN) process. In this work, atenolol biodegradation by PN cultures was investigated by maintaining ammonium and pH at different levels. For the first time, free nitrous acid (FNA), other than ammonium, pH, and free ammonia, was demonstrated to inhibit atenolol removal, with biodegradation efficiencies of ∼98, ∼67, and ∼28% within 6 days at average FNA levels of 0, 0.03, and 0.19 mg-N L-1, respectively. Ammonia-oxidizing bacteria (AOB)-induced metabolism was predominant despite varying FNA concentrations. In the absence of ammonium/FNA, atenolol was mostly biodegraded via AOB-induced metabolism (65%) and heterotroph-induced metabolism (33%). AOB-induced metabolism was largely inhibited (down to 29%) at 0.03 mg-N L-1 FNA, while ∼27 and ∼11% were degraded via heterotroph-induced metabolism and AOB-induced cometabolism, respectively. Higher FNA (0.19 mg-N L-1) substantially reduced atenolol biodegradation via heterotroph-induced metabolism (4%), AOB-induced metabolism (16%), and AOB-induced cometabolism (8%). Newly identified products and pathways were related to metabolic types and FNA levels: (i) deamination and decarbonylation (AOB-induced cometabolism, 0.03 mg-N L-1 FNA); (ii) deamination from atenolol acid (heterotrophic biodegradation); and (iii) nitro-substitution (reaction with nitrite). This suggests limiting FNA to realize simultaneous nitrogen and pharmaceutical removal during the sidestream process.

Genome-Wide Characterization and Expression Profiling of the GRAS Gene Family in Salt and Alkali Stresses in Miscanthus sinensis.

The GRAS family genes encode plant-specific transcription factors that play important roles in a diverse range of developmental processes and abiotic stress responses. However, the information of GRAS gene family in the bioenergy crop Miscanthus has not been available. Here, we report the genome-wide identification of GRAS gene family in Micanthus sinensis. A total of 123 MsGRAS genes were identified, which were divided into ten subfamilies based on the phylogenetic analysis. The co-linearity analysis revealed that 59 MsGRAS genes experienced segmental duplication, forming 35 paralogous pairs. The expression of six MsGRAS genes in responding to salt, alkali, and mixed salt-alkali stresses was analyzed by transcriptome and real-time quantitative PCR (RT-qPCR) assays. Furthermore, the role of MsGRAS60 in salt and alkali stress response was characterized in transgenic Arabidopsis. The MsGRAS60 overexpression lines exhibited hyposensitivity to abscisic acid (ABA) treatment and resulted in compromised tolerance to salt and alkali stresses, suggesting that MsGRAS60 is a negative regulator of salt and alkali tolerance via an ABA-dependent signaling pathway. The salt and alkali stress-inducible MsGRAS genes identified serve as candidates for the improvement of abiotic stress tolerance in Miscanthus.

Cometabolic biodegradation of antibiotics by ammonia oxidizing microorganisms during wastewater treatment processes.

Studies on antibiotic removal during wastewater treatment processes are crucial since their release into the environment could bring potential threats to human health and ecosystem. Cometabolic biodegradation of antibiotics by ammonia oxidizing microorganisms (AOMs) has received special attentions due to the enhanced removal of antibiotics during nitrification processes. However, the interactions between antibiotics and AOMs are less well-elucidated. In this review, the recent research proceedings on cometabolic biodegradation of antibiotics by AOMs were summarized. Ammonia oxidizing bacteria (AOB), ammonia oxidizing archaea (AOA) and complete ammonia oxidizers (comammox) played significant roles in both nitrification and cometabolic biodegradation of antibiotics. Antibiotics at varying concentrations might pose inhibiting or stimulating effect on AOMs, influencing the microbial activity, community abundance and ammonia monooxygenase subunit A gene expression level. AOMs-induced cometabolic biodegradation products were analyzed as well as the corresponding pathways for each type of antibiotics. The effects of ammonium availability, initial antibiotic concentration, sludge retention time and temperature were assessed on the cometabolic biodegradation efficiencies of antibiotics. This work might provide further insights into the fate and removal of antibiotics during nitrification processes.

TLNPMD: Prediction of miRNA-Disease Associations Based on miRNA-Drug-Disease Three-Layer Heterogeneous Network.

Many microRNAs (miRNAs) have been confirmed to be associated with the generation of human diseases. Capturing miRNA-disease associations (M-DAs) provides an effective way to understand the etiology of diseases. Many models for predicting M-DAs have been constructed; nevertheless, there are still several limitations, such as generally considering direct information between miRNAs and diseases, usually ignoring potential knowledge hidden in isolated miRNAs or diseases. To overcome these limitations, in this study a novel method for predicting M-DAs was developed named TLNPMD, highlights of which are the introduction of drug heuristic information and a bipartite network reconstruction strategy. Specifically, three bipartite networks, including drug-miRNA, drug-disease, and miRNA-disease, were reconstructed as weighted ones using such reconstruction strategy. Based on these weighted bipartite networks, as well as three corresponding similarity networks of drugs, miRNAs and diseases, the miRNA-drug-disease three-layer heterogeneous network was constructed. Then, this heterogeneous network was converted into three two-layer heterogeneous networks, for each of which the network path computational model was employed to predict association scores. Finally, both direct and indirect miRNA-disease paths were used to predict M-DAs. Comparative experiments of TLNPMD and other four models were performed and evaluated by five-fold and global leave-one-out cross validations, results of which show that TLNPMD has the highest AUC values among those of compared methods. In addition, case studies of two common diseases were carried out to validate the effectiveness of the TLNPMD. These experiments demonstrate that the TLNPMD may serve as a promising alternative to existing methods for predicting M-DAs.

Enhanced biodegradation of ciprofloxacin by enriched nitrifying sludge: assessment of removal pathways and microbial responses.

Antibiotics are mostly collected by sewage systems, but not completely removed within wastewater treatment plants. Their release to aquatic environment poses a great threat to public health. This study evaluated the removal of a widely used fluoroquinolone antibiotic, ciprofloxacin, in enriched nitrifying culture through a series of experiments by controlling ammonium concentrations and inhibiting functional microorganisms. The removal efficiency of ciprofloxacin at an initial concentration of 50 µg L-1 reached 81.86 ± 3.21% in the presence of ammonium, while only 22.83 ± 8.22% of ciprofloxacin was removed in its absence. A positive linear correlation was found between the ammonia oxidation rate (AOR) and ciprofloxacin biodegradation rate. These jointly confirmed the importance of the AOB-induced cometabolism in ciprofloxacin biodegradation, with adsorption and metabolic degradation pathways playing minor roles. The continuous exposure of AOB to ciprofloxacin led to decreases of ammonia monooxygenase (AMO) activities and AOR. The antibacterial effects of ciprofloxacin and its biodegradation products were further evaluated and the results revealed that biodegradation products of ciprofloxacin exhibited less toxicity compared to the parent compound, implying the potential application of cometabolism in alleviation of antimicrobial activity. The findings provided new insights into the AOB-induced cometabolic biodegradation of fluoroquinolone antibiotics.

Serrate-Associated Protein 1, a splicing-related protein, promotes miRNA biogenesis in Arabidopsis.

MicroRNAs (miRNAs) are essential regulators of gene expression in metazoans and plants. In plants, most miRNAs are generated from primary miRNA transcripts (pri-miRNAs), which are processed by the Dicer-like 1 (DCL1) complex along with accessory proteins. Serrate-Associated Protein 1 (SEAP1), a conserved splicing-related protein, has been studied in human and yeast. However, the functions of SEAP1 in plants remain elusive. Lack of SEAP1 results in embryo lethality and knockdown of SEAP1 by an artificial miRNA (amiRSEAP1 ) causes pleiotropic developmental defects and reduction in miRNA accumulation. SEAP1 associates with the DCL1 complex, and may promote the interaction of the DCL1 complexes with pri-miRNAs. SEAP1 also enhances pri-miRNA accumulation, but does not affect pri-miRNA transcription, suggesting it may indirectly or directly stabilize pri-miRNAs. In addition, SEAP1 affects the splicing of some pri-miRNAs and intron retention of messenger RNAs at global levels. Our findings uncover both conserved and novel functions of SEAP1 in plants. Besides the role as a splicing factor, SEPA1 may promote miRNA biogenesis by positively modulating pri-miRNA splicing, processing and/or stability.

MAC3A and MAC3B, Two Core Subunits of the MOS4-Associated Complex, Positively Influence miRNA Biogenesis.

MAC3A and MAC3B are conserved U-box-containing proteins in eukaryotes. They are subunits of the MOS4-associated complex (MAC) that plays essential roles in plant immunity and development in Arabidopsis thaliana However, their functional mechanisms remain elusive. Here, we show that Arabidopsis MAC3A and MAC3B act redundantly in microRNA (miRNA) biogenesis. Lack of both MAC3A and MAC3B in the mac3b mac3b double mutant reduces the accumulation of miRNAs, causing elevated transcript levels of miRNA targets. mac3a mac3b also decreases the levels of primary miRNA transcripts (pri-miRNAs). However, MAC3A and MAC3B do not affect the promoter activity of genes encoding miRNAs (MIR genes), suggesting that they may not affect MIR transcription. This result, together with the fact that MAC3A associates with pri-miRNAs in vivo, indicates that MAC3A and MAC3B may stabilize pri-miRNAs. Furthermore, we find that MAC3A and MAC3B interact with the DCL1 complex that catalyzes miRNA maturation, promote DCL1 activity, and are required for the localization of HYL1, a component of the DCL1 complex. Besides MAC3A and MAC3B, two other MAC subunits, CDC5 and PRL1, also function in miRNA biogenesis. Based on these results, we propose that MAC functions as a complex to control miRNA levels through modulating pri-miRNA transcription, processing, and stability.

Aromatic Aza-Claisen Rearrangement of Arylpropargylammonium Salts Generated in situ from Arynes and Tertiary Propargylamines.

The charge-accelerated aza-Claisen rearrangement of ammonium salts serves as a key step in the construction of complex nitrogen-containing molecules. However, much less attention has been paid to the aromatic aza-Claisen rearrangement than to the aliphatic one. Herein, we report an unprecedented aromatic aza-Claisen rearrangement of arylpropargylammonium salts, generated in situ from arynes and tertiary propargylamines, delivering structurally diverse 2-propargylanilines in moderate to good yields with high regioselectivity. This rearrangement proceeds in the absence of strong bases or transition metals, is compatible with moisture and air, tolerates a wide variety of functional groups, and is amenable to forming 11- to 13-membered heterocycles with a triple bond. The 2-propargylaniline products were treated with aluminum chloride in ethanol to afford multisubstituted indoles in moderate to excellent yields. Finally, a series of deuterium-labeling experiments was performed to elucidate the reaction mechanism.

Controllable coupling between an ultra-high-Q microtoroid cavity and a graphene monolayer for optical filtering and switching applications.

Whispering-gallery-mode optical microresonators have found impactful applications in various areas due to their remarkable properties such as ultra-high quality factor (Q-factor), small mode volume, and strong evanescent field. Among these applications, controllable tuning of the optical Q-factor is vital for on-chip optical modulation and various opto-electronic devices. Here, we report an experimental demonstration with a hybrid structure formed by an ultra-high-Q microtoroid cavity and a graphene monolayer. Thanks to the strong interaction of the evanescent wave with the graphene, the structure allows the Q-factor to be controllably varied in the range of 3.9 × 105 ∼ 6.2 × 107 by engineering optical absorption via changing the gap distance in between. At the same time, a resonant wavelength shift of 32 pm was also observed. Besides, the scheme enables us to approach the critical coupling with a coupling depth of 99.6%. As potential applications in integrated opto-electronic devices, we further use the system to realize a tunable optical filter with tunable bandwidth from 116.5 MHz to 2.2 GHz as well as an optical switch with a maximal extinction ratio of 31 dB and response time of 21 ms.

The Arabidopsis MOS4-Associated Complex Promotes MicroRNA Biogenesis and Precursor Messenger RNA Splicing.

In Arabidopsis thaliana, the MOS4-ASSOCIATED COMPLEX (MAC) is required for defense and development. The evolutionarily conserved, putative RNA helicase MAC7 is a component of the Arabidopsis MAC, and the human MAC7 homolog, Aquarius, is implicated in pre-mRNA splicing. Here, we show that mac7-1, a partial loss-of-function mutant in MAC7, and two other MAC subunit mutants, mac3a mac3b and prl1 prl2 (pleiotropic regulatory locus), exhibit reduced microRNA (miRNA) levels, indicating that MAC promotes miRNA biogenesis. The mac7-1 mutant shows reduced primary miRNA (pri-miRNA) levels without affecting miRNA gene (MIR) promoter activity or the half-life of pri-miRNA transcripts. As a nuclear protein, MAC7 is not concentrated in dicing bodies, but it affects the localization of HYPONASTIC LEAVES1 (HYL1), a key protein in pri-miRNA processing, to dicing bodies. Immunoprecipitation of HYL1 retrieved 11 known MAC subunits, including MAC7, indicating association between HYL1 and MAC. We propose that MAC7 links MIR transcription to pri-miRNA processing. RNA-seq analysis showed that downregulated genes in MAC subunit mutants are mostly involved in plant defense and stimulus responses, confirming a role of MAC in biotic and abiotic stress responses. We also discovered global intron retention defects in mutants in three subunits of MAC, thus linking MAC function to splicing in Arabidopsis.

SMA1, a homolog of the splicing factor Prp28, has a multifaceted role in miRNA biogenesis in Arabidopsis.

MicroRNAs (miRNAs) are a class of small non-coding RNAs that repress gene expression. In plants, the RNase III enzyme Dicer-like (DCL1) processes primary miRNAs (pri-miRNAs) into miRNAs. Here, we show that SMALL1 (SMA1), a homolog of the DEAD-box pre-mRNA splicing factor Prp28, plays essential roles in miRNA biogenesis in Arabidopsis. A hypomorphic sma1-1 mutation causes growth defects and reduces miRNA accumulation correlated with increased target transcript levels. SMA1 interacts with the DCL1 complex and positively influences pri-miRNA processing. Moreover, SMA1 binds the promoter region of genes encoding pri-miRNAs (MIRs) and is required for MIR transcription. Furthermore, SMA1 also enhances the abundance of the DCL1 protein levels through promoting the splicing of the DCL1 pre-mRNAs. Collectively, our data provide new insights into the function of SMA1/Prp28 in regulating miRNA abundance in plants.

STV1, a ribosomal protein, binds primary microRNA transcripts to promote their interaction with the processing complex in Arabidopsis.

MicroRNAs (miRNAs) are key regulators of gene expression. They are processed from primary miRNA transcripts (pri-miRNAs), most of which are transcribed by DNA-dependent polymerase II (Pol II). miRNA levels are precisely controlled to maintain various biological processes. Here, we report that SHORT VALVE 1 (STV1), a conserved ribosomal protein, acts in miRNA biogenesis in Arabidopsis A portion of STV1 localizes in the nucleus and binds pri-miRNAs. Using pri-miR172b as a reporter, we show that STV1 binds the stem-loop flanked by a short 5' arm within pri-miRNAs. Lack of STV1 reduces the association of pri-miRNAs with their processing complex. These data suggest that STV1 promotes miRNA biogenesis through facilitating the recruitment of pri-miRNAs to their processing complex. Furthermore, we show that STV1 indirectly involves in the occupancy of Pol II at the promoters of miRNA coding genes (MIR) and influences MIR promoter activities. Based on these results, we propose that STV1 refines the accumulation of miRNAs through its combined effects on pri-miRNA processing and transcription. This study uncovers an extraribosomal function of STV1.

DAWDLE Interacts with DICER-LIKE Proteins to Mediate Small RNA Biogenesis.

DAWDLE (DDL) is a conserved forkhead-associated (FHA) domain-containing protein with essential roles in plant development and immunity. It acts in the biogenesis of microRNAs (miRNAs) and endogenous small interfering RNAs (siRNAs), which regulate gene expression at the transcriptional and/or posttranscriptional levels. However, the functional mechanism of DDL and its impact on exogenous siRNAs remain elusive. Here, we report that DDL is required for the biogenesis of siRNAs derived from sense transgenes and inverted-repeat transgenes. Furthermore, we show that a mutation in the FHA domain of DDL disrupts the interaction of DDL with DICER-LIKE1 (DCL1), which is the enzyme that catalyzes miRNA maturation from primary miRNA transcripts (pri-miRNAs), resulting in impaired pri-miRNA processing. Moreover, we demonstrate that DDL interacts with DCL3, which is a DCL1 homolog responsible for siRNA production, and this interaction is crucial for optimal DCL3 activity. These results reveal that the interaction of DDL with DCLs is required for the biogenesis of miRNAs and siRNAs in Arabidopsis (Arabidopsis thaliana).