Small object detection is one of the key challenges in the current computer vision field due to the low amount of information carried and the information loss caused by feature extraction. You Only ...Look Once v5 (YOLOv5) adopts the Path Aggregation Network to alleviate the problem of information loss, but it cannot restore the information that has been lost. To this end, an auxiliary information-enhanced YOLO is proposed to improve the sensitivity and detection performance of YOLOv5 to small objects. Firstly, a context enhancement module containing a receptive field size of 21×21 is proposed, which captures the global and local information of the image by fusing multi-scale receptive fields, and introduces an attention branch to enhance the expressive ability of key features and suppress background noise. To further enhance the feature expression ability of small objects, we introduce the high- and low-frequency information decomposed by wavelet transform into PANet to participate in multi-scale feature fusion, so as to solve the problem that the features of small objects gradually disappear after multiple downsampling and pooling operations. Experiments on the challenging dataset Tsinghua–Tencent 100 K show that the mean average precision of the proposed model is 9.5% higher than that of the original YOLOv5 while maintaining the real-time speed, which is better than the mainstream object detection models.
Display omitted
•Ultra-highly filled wood fiber/polyethylene composites (UH-WPCs) was successfully fabricated using maleic anhydride grafted polyethylene (MAPE) as matrix or compatibilizer.•Only 25% ...and 30% MAPE was grafted on wood fiber at 80 wt% loading using MAPE as matrix and compatibilizer, respectively.•Mechanical properties of the compatibilized UH-WPCs were not positively correlated with the absolute content of MAPE grafted on wood fiber.•The esterification is not the key determinant for the interfacial adhesion mechanisms using MAPE as compatibilizer in UH-WPCs.
To investigate whether the esterification reaction was the dominant factor that improved the interface compatibility of wood-plastic composites and accordingly their performances, ultra-highly filled wood fiber (WF)/polyethylene composites (UH-WPCs) was fabricated using maleic anhydride grafted polyethylene (MAPE) as compatibilizer or matrix with WF content of 60–85 wt%. The FTIR and TGA results confirm the absolute content of MAPE grafted on WF was 4.5% and 0.9% for the UH-WPCs with 80 wt% WF using MAPE as matrix and compatibilizer, respectively. The UH-WPCs using MAPE as matrix or compatibilizer exhibited considerable higher mechanical properties, better creep resistance, and lower water absorption compared to the uncompatibilized ones. Compared with the uncompatibilized composites with 80 wt% WF, the tensile and flexural strengths were increased by 187% and 186% for using MAPE as matrix, and 224% and 189% for using MAPE as compatibilizer, respectively. These results reveal that the mechanical properties of the UH-WPCs with MAPE were not positively correlated with the absolute content of MAPE grafted on WF. The above findings confirmed that the esterification was not the key determinant for interfacial adhesion mechanisms using MAPE as compatibilizer in UH-WPCs, and some other more important factors may exist.
The glandular secretory trichomes (GSTs) on Artemisia annua leaves have the capacity to secrete and store artemisinin, a compound which is the most effective treatment for uncomplicated malaria. An ...effective strategy to improve artemisinin content is therefore to increase the density of GSTs in A. annua. However, the formation mechanism of GSTs remains poorly understood.
To explore the mechanisms of GST initiation in A. annua, we screened myeloblastosis (MYB) transcription factor genes from a GST transcriptome database and identified a MIXTA transcription factor, AaMIXTA1, which is expressed predominantly in the basal cells of GST in A. annua. Overexpression and repression of AaMIXTA1 resulted in an increase and decrease, respectively, in the number of GSTs as well as the artemisinin content in transgenic plants.
Transcriptome analysis and cuticular lipid profiling showed that AaMIXTA1 is likely to be responsible for activating cuticle biosynthesis. In addition, dual-luciferase reporter assays further demonstrated that AaMIXTA1 could directly activate the expression of genes related to cuticle biosynthesis.
Taken together, AaMIXTA1 regulated cuticle biosynthesis and prompted GST initiation without any abnormal impact on the morphological structure of the GSTs and so provides a new way to improve artemisinin content in this important medicinal plant.
Artemisinin is a type of sesquiterpene lactone well known as an antimalarial drug, and is specifically produced in glandular trichomes of Artemisia annua. However, the regulatory network for the ...artemisinin biosynthetic pathway remains poorly understood. Exploration of trichome-specific transcription factors would facilitate the elucidation of regulatory mechanism of artemisinin biosynthesis.
The WRKY transcription factor GLANDULAR TRICHOME-SPECIFIC WRKY 1 (AaGSW1) was cloned and analysed in A. annua. AaGSW1 exhibited similar expression patterns to the trichome-specific genes of the artemisinin biosynthetic pathway and AP2/ERF transcription factor AaORA. A β-glucuronidase (GUS) staining assay further demonstrated that AaGSW1 is a glandular trichome-specific transcription factor.
AaGSW1 positively regulates CYP71AV1 and AaORA expression by directly binding to the W-box motifs in their promoters. Overexpression of AaGSW1 in A. annua significantly improves artemisinin and dihydroartemisinic acid contents; moreover, AaGSW1 can be directly regulated by AaMYC2 and AabZIP1, which are positive regulators of jasmonate (JA)-and abscisic acid (ABA)-mediated artemisinin biosynthetic pathways, respectively.
These results demonstrate that AaGSW1 is a glandular trichome-specific WRKY transcription factor and a positive regulator in the artemisinin biosynthetic pathway. Moreover, we propose that two trifurcate feed-forward pathways involving AaGSW1, CYP71AV1 and AaMYC2/AabZIP1 function in the JA/ABA response in A. annua.
Tanshinone is a group of active diterpenes, which are widely used in the treatment of cardiovascular disease. In this study, methyl jasmonate (MJ) and salicylic acid (SA) were used to investigate ...their effects on tanshinone accumulation and biosynthetic gene expression in the hairy roots of geranylgeranyl diphosphate synthase (SmGGPPS) overexpression line (G50) in Salvia miltiorrhiza. High‐performance liquid chromatography analysis showed that total tanshinone content in G50 was obviously increased by 3.10‐fold (11.33 mg/g) with MJ at 36 H and 1.63 times (5.95 mg/g) after SA treatment for 36 H in comparison with their mimic treatment control. Furthermore, quantitative reverse‐transcription PCR analysis showed that the expression of isopentenyl‐diphosphate delta‐isomerase (SmIPPI), SmGGPPS, copalyl diphosphate synthase (SmCPS), and kaurene synthase‐like (SmKSL) increased significantly with MJ treatment. However, the expression of SmIPPI reached the highest level at 144 H, whereas those of SmGGPPS, SmCPS, and SmKSL only increased slightly with SA treatment. The two elicitor treatments suggested that tanshinone accumulation positively correlated to the expression of key genes such as SmGGPPS, SmCPS, and SmKSL. Meanwhile, the study also indicated that it was a feasible strategy to combine elicitor treatment with transgenic technology for the enhancement of tanshinone, which paved the way for further metabolic engineering of tanshinone biosynthesis.
Tanshinones, one group of bioactive diterpenes, were widely used in the treatment of cardiovascular diseases. WRKYs play important roles in plant metabolism, but their regulation mechanism in
remains ...elusive. In this study, one
transcription factor
was isolated and functionally characterized from
. Multiple sequence alignment and phylogenetic tree analysis showed SmWRKY1 shared high homology with other plant WRKYs such as CrWRKY1.
was found predominantly expressed in leaves and stems, and was responsive to salicylic acid (SA), methyl jasmonate (MeJA), and nitric oxide (NO) treatment. Subcellular localization analysis found that SmWRKY1 was localized in the nucleus. Over-expression of
significantly elevated the transcripts of genes coding for enzymes in the MEP pathway especially 1-deoxy-D-xylulose-5-phosphate synthase (
) and 1-deoxy-D-xylulose-5-phosphate reductoisomerase (
), resulted in over fivefold increase in tanshinones production in transgenic lines (up to 13.7 mg/g DW) compared with the control lines. A dual-luciferase (Dual-LUC) assay showed that SmWRKY1 can positively regulate
expression by binding to its promoter. Our work revealed that SmWRKY1 participated in the regulation of tanshinones biosynthesis and acted as a positive regulator through activating
in the MEP pathway, thus provided a new insight to further explore the regulation mechanism of tanshinones biosynthesis.
The utilization of four types of biomass particles, including hardwood (poplar), softwood (radiata pine), crop (wheat straw) and bamboo (moso bamboo), as reinforcing fillers in preparing high density ...polyethylene (HDPE) based composites was studied. To improve interfacial compatibility, maleic anhydride grafted polyethylene (MAPE) was applied as the coupling agent. The effects of the biomass species on the mechanical and water absorption properties of the resulting composites were evaluated based on chemical composition analysis. A creep-recovery test was conducted in single cantilever mode using a dynamic mechanical analyzer. Results show that the four types of biomass particles had similar chemical compositions but different composition contents. Poplar particles with high cellulose content loading in the HDPE matrix exhibited higher tensile and flexure properties and creep resistance. Fracture morphology analysis indicated a weak particle-matrix interface in wheat straw based composites. Given the high crystallinity and minimum hemicellulose content, the moso bamboo reinforced composite showed high impact strength and better water resistance.
Display omitted
•SmMYB98 was predominantly expressed in the lateral roots of Salvia miltiorrhiza.•Tanshinones and salvianolic acids were improved in the SmMYB98-OE hairy roots.•Tanshinone and ...salvianolic acid contents in SmMYB98-KO lines were reduced.•SmMYB98 regulates the expression of tanshinones and salvianolic acids biosynthetic genes.•SmMYB98 negatively regulates the biosynthesis of gibberellins in S. miltiorrhiza.
Salvia miltiorrhiza Bunge is an herb rich in bioactive tanshinone and salvianolic acid compounds. It is primarily used as an effective medicine for treating cardiovascular and cerebrovascular diseases. Liposoluble tanshinones and water-soluble phenolic acids are a series of terpenoids and phenolic compounds, respectively. However, the regulation mechanism for the simultaneous promotion of tanshinone and salvianolic acid biosynthesis remains unclear. This study identified a R2R3-MYB subgroup 20 transcription factor (TF), SmMYB98, which was predominantly expressed in S. miltiorrhiza lateral roots. The accumulation of major bioactive metabolites, tanshinones, and salvianolic acids, was improved in SmMYB98 overexpression (OE) hairy root lines, but reduced in SmMYB98 knockout (KO) lines. The qRT-PCR analysis revealed that the transcriptional expression levels of tanshinone and salvianolic acid biosynthesis genes were upregulated by SmMYB98-OE and downregulated by SmMYB98-KO. Dual-Luciferase (Dual-LUC) assays demonstrated that SmMYB98 significantly activated the transcription of SmGGPPS1, SmPAL1, and SmRAS1. These results suggest that SmMYB98-OE can promote tanshinone and salvianolic acid production. The present findings illustrate the exploitation of R2R3-MYB in terpenoid and phenolic biosynthesis, as well as provide a feasible strategy for improving tanshinone and salvianolic acid contents by MYB proteins in S. miltiorrhiza.
Abstract
The limited bioavailability of plant-derived natural products with anticancer activity poses major challenges to the pharmaceutical industry. An example of this is camptothecin, a ...monoterpene indole alkaloid with potent anticancer activity that is extracted at very low concentrations from woody plants. Recently, camptothecin biosynthesis has been shown to become biotechnologically amenable in hairy-root systems of the natural producer
Ophiorrhiza pumila
. Here, time-course expression and metabolite analyses were performed to identify novel transcriptional regulators of camptothecin biosynthesis in
O. pumila
. It is shown here that camptothecin production increased over cultivation time and that the expression pattern of the WRKY transcription factor encoding gene
OpWRKY2
is closely correlated with camptothecin accumulation. Overexpression of
OpWRKY2
led to a more than three-fold increase in camptothecin levels. Accordingly, silencing of
OpWRKY2
correlated with decreased camptothecin levels in the plant. Further detailed molecular characterization by electrophoretic mobility shift, yeast one-hybrid and dual-luciferase assays showed that OpWRKY2 directly binds and activates the central camptothecin pathway gene
OpTDC
. Taken together, the results of this study demonstrate that OpWRKY2 acts as a direct positive regulator of camptothecin biosynthesis. As such, a feasible strategy for the over-accumulation of camptothecin in a biotechnologically amenable system is presented.
The anticancer drug camptothecin (CPT), first isolated from Camptotheca acuminata, was subsequently discovered in unrelated plants, including Ophiorrhiza pumila. Unlike known monoterpene indole ...alkaloids, CPT in C. acuminata is biosynthesized via the key intermediate strictosidinic acid, but how O. pumila synthesizes CPT has not been determined.
In this study, we used nontargeted metabolite profiling to show that 3α-(S)-strictosidine and 3-(S), 21-(S)-strictosidinic acid coexist in O. pumila. After identifying the enzymes OpLAMT, OpSLS, and OpSTR as participants in CPT biosynthesis, we compared these enzymes to their homologues from two other representative CPT-producing plants, C. acuminata and Nothapodytes nimmoniana, to elucidate their phylogenetic relationship. Finally, using labelled intermediates to resolve the CPT biosynthesis pathway in O. pumila, we showed that 3α-(S)-strictosidine, not 3-(S), 21-(S)-strictosidinic acid, is the exclusive intermediate in CPT biosynthesis.
In our study, we found that O. pumila, another representative CPT-producing plant, exhibits metabolite diversity in its central intermediates consisting of both 3-(S), 21-(S)-strictosidinic acid and 3α-(S)-strictosidine and utilizes 3α-(S)-strictosidine as the exclusive intermediate in the CPT biosynthetic pathway, which differs from C. acuminata. Our results show that enzymes likely to be involved in CPT biosynthesis in O. pumila, C. acuminata, and N. nimmoniana have evolved divergently. Overall, our new data regarding CPT biosynthesis in O. pumila suggest evolutionary divergence in CPT-producing plants. These results shed new light on CPT biosynthesis and pave the way towards its industrial production through enzymatic or metabolic engineering approaches.
PDF
