Stretchable Optical Diffuser Constructed by Alternate Procedure of Interfacial Complexation and Thermal Crosslinking.

Stretchable optical diffuser is an indispensable photon management element in wearable display devices. Herein, a novel optical diffuser constructed by interfacial hydrogen bonding complexation of methylcellulose (MC), poly(ethylene oxide) (PEO), and polymer complex nanoparticles (PCNP) on transparent polydimethylsiloxane (PDMS) substrate is proposed. The introduction of PEO can toughen the complex film and endow the coating with stretchability. With proper thermal treatment, the polymer complex can be crosslinked through esterification which shows an improved optical diffusion performance and durability. The optimized film exhibits 92% of transmittance (T), 93% of haze (H), and 73% of elongation. It also presents a desirable optical diffusion effect about 88% of T and 93% of H in the stretching state. Moreover, the resulting complex film shows excellent anti-fatigue capacity which maintains 90% of T and 90% of H after 10 000 stretching cycles. The reported polymer complex film broadens the application of interfacial complexation and demonstrates potential to apply in the integrated wearable optical devices.

The formation and accumulation of protein-networks by physical interactions in the rapid occlusion of laticifer cells in rubber tree undergoing successive mechanical wounding.

BACKGROUND: Although the wound response of plants has been extensively studied, little is known of the rapid occlusion of wounded cell itself. The laticifer in rubber tree is a specific type of tissue for natural rubber biosynthesis and storage. In natural rubber production, tapping is used to harvest the latex which flows out from the severed laticifer in the bark. Therefore, study of the rapid wound-occlusion of severed laticifer cells is important for understanding the rubber tree being protected from the continuously mechanical wounding. RESULTS: Using cytological and biochemical techniques, we revealed a biochemical mechanism for the rapid occlusion of severed laticifer cells. A protein-network appeared rapidly after tapping and accumulated gradually along with the latex loss at the severed site of laticifer cells. Triple immunofluorescence histochemical localization showed that the primary components of the protein-network were chitinase, ß-1,3-glucanase and hevein together with pro-hevein (ProH) and its carboxyl-terminal part. Molecular sieve chromatography showed that the physical interactions among these proteins occurred under the condition of neutral pH. The interaction of ß-1,3-glucanase respectively with hevein, chitinase and ProH was testified by surface plasmon resonance (SPR). The interaction between actin and ß-1,3-glucanase out of the protein inclusions of lutoids was revealed by pull-down. This interaction was pharmacologically verified by cytochalasin B-caused significant prolongation of the duration of latex flow in the field. CONCLUSIONS: The formation of protein-network by interactions of the proteins with anti-pathogen activity released from lutoids and accumulation of protein-network by binding to the cytoskeleton are crucial for the rapid occlusion of laticifer cells in rubber tree. The protein-network at the wounded site of laticifer cells provides not only a physical barrier but also a biochemical barrier to protect the wounded laticifer cells from pathogen invasion.

Jasmonate signalling in the regulation of rubber biosynthesis in laticifer cells of rubber tree, Hevea brasiliensis.

Rubber trees are the world's major source of natural rubber. Rubber-containing latex is obtained from the laticifer cells of the rubber tree (Hevea brasiliensis) via regular tapping. Rubber biosynthesis is a typical isoprenoid metabolic process in the laticifer cells; however, little is known about the positive feedback regulation caused by the loss of latex that occurs through tapping. In this study, we demonstrate the crucial role of jasmonate signalling in this feedback regulation. The endogenous levels of jasmonate, the expression levels of rubber biosynthesis-related genes, and the efficiency of in vitro rubber biosynthesis were found to be significantly higher in laticifer cells of regularly tapped trees than those of virgin (i.e. untapped) trees. Application of methyl jasmonate had similar effects to latex harvesting in up-regulating the rubber biosynthesis-related genes and enhancing rubber biosynthesis. The specific jasmonate signalling module in laticifer cells was identified as COI1-JAZ3-MYC2. Its activation was associated with enhanced rubber biosynthesis via up-regulation of the expression of a farnesyl pyrophosphate synthase gene and a small rubber particle protein gene. The increase in the corresponding proteins, especially that of farnesyl pyrophosphate synthase, probably contributes to the increased efficiency of rubber biosynthesis. To our knowledge, this is the first study to reveal a jasmonate signalling pathway in the regulation of rubber biosynthesis in laticifer cells. The identification of the specific jasmonate signalling module in the laticifer cells of the rubber tree may provide a basis for genetic improvement of rubber yield potential.

pH-Responsive Janus Film Constructed with Hydrogen-Bonding Assembly and Dopamine Chemistry.

Poly(acrylic acid) (PAA) was partially grafted with dopamine (PAA-dopa), and then layer-by-layer assembled with poly(vinylpyrrolidone) (PVPON) to prepare hydrogen-bonded (PVPON/PAA-dopa) n film. Polydopamine (PDA) was deposited on (PVPON/PAA-dopa) n film in the presence of oxidant, and hence the whole (PVPON/PAA-dopa) nPDA film was cross-linked. (PVPON/PAA-dopa) nPDA could be utilized as a platform to produce the free-standing Janus film because of the easy detaching process and various chemical reactivity of PDA layer. Ag nanoparticles were formed on (PVPON/PAA-dopa) nPDA film by electroless metallization. 1 H,1 H,2 H,2 H-Perfluorodecanethiol (PFDT) was used to further modify the film through Michael addition. After detaching from the substrate, (PVPON/PAA-dopa)20PDA/Ag/PFDT exhibits reversible swelling-shrinking behavior as the pH value changes. This free-standing film shows Janus character, one side is hydrophobic, whereas the other side is hydrophilic. In addition, the hydrophobic surface exhibits a surface-enhanced Raman scattering effect, whereas the hydrophilic side does not.

Reversible swelling-shrinking behavior of hydrogen-bonded free-standing thin film stabilized by catechol reaction.

Dopamine-modified poly(acrylic acid) (PAA-dopa) and poly(vinylpyrrolidone) (PVPON) was layer-by-layer (LbL) assembled to prepare thin film based on hydrogen bonding. The carboxylic group of acrylic acid and the phenolic hydroxyl group of dopamine can both act as hydrogen bond donors. The critical assembly and the critical disintegration pH values of PVPON/PAA-dopa film are enhanced compared with PVPON/PAA film. The hydrogen-bonded PVPON/PAA-dopa thin film can be cross-linked via catechol chemistry of dopamine. After cross-linking, the film can be exfoliated from the substrate in alkaline solution to get a free-standing film. Moreover, by tuning the pH value, deprotonation and protonation of PAA will make the hydrogen bond in the film break and reconstruct, which induces that the free-standing film has a reversible swelling-shrinking behavior.

Polymer Complex Multilayers for Drug Delivery and Medical Devices.

Polymer complex multilayers (PCMs) can be engineered into various structures with tunable properties via layer-by-layer (LBL) assembly driven by noncovalent forces. Due to their ease of preparation, capability of integrating multiple functional components, and excellent substrate compliance, biocompatible PCMs as coating materials or individual entities have attracted extensive attention in biomedical applications. This Spotlight on Applications presents recent progress on PCMs applied for drug delivery and medical devices. We provide several examples to address the importance of using PCM platforms to achieve controlled drug delivery including stimuli-triggered release, sustained release, and spatiotemporal sequential release. The effects of PCM coatings on the bioresponse regulation and performance enhancement of implantable devices are also highlighted. Moreover, the design and fabrication of flexible electrical and optical elements modified with LBL PCMs have been discussed, which demonstrates the great potential to advance emerging wearable devices for disease monitoring and health management.

Genomic insight into domestication of rubber tree.

Understanding the genetic basis of rubber tree (Hevea brasiliensis) domestication is crucial for further improving natural rubber production to meet its increasing demand worldwide. Here we provide a high-quality H. brasiliensis genome assembly (1.58 Gb, contig N50 of 11.21 megabases), present a map of genome variations by resequencing 335 accessions and reveal domestication-related molecular signals and a major domestication trait, the higher number of laticifer rings. We further show that HbPSK5, encoding the small-peptide hormone phytosulfokine (PSK), is a key domestication gene and closely correlated with the major domestication trait. The transcriptional activation of HbPSK5 by myelocytomatosis (MYC) members links PSK signaling to jasmonates in regulating the laticifer differentiation in rubber tree. Heterologous overexpression of HbPSK5 in Russian dandelion (Taraxacum kok-saghyz) can increase rubber content by promoting laticifer formation. Our results provide an insight into target genes for improving rubber tree and accelerating the domestication of other rubber-producing plants.

Optical diffuser constructed by assembly of cellulose ether and polymer complex particles.

Using sustainable cellulose and its derivatives to prepare optical diffuser is an economic and green approach. Herein, we report a novel optical diffuser constructed by interfacial assembly of cellulose ether (CE) and polymer complex particles (PCP) on flexible and transparent poly(ethylene terephthalate) (PET) substrate. Owning to the rich hydroxyl groups of CEs, the complex thin film can be further crosslinked by thermal treatment which greatly improves the optical diffusion performance and durability. Without crosslinking, haze (H) of the cellulose complex film is about 81 %, and the film will dissolve in high pH value solution. While after the proper crosslinking, H of the film increases to 95 %, and the film can resist the erosion of high pH solution. Moreover, CE/PCP complex film shows improved anti-bending capacity compared with commercially available optical diffuser for liquid crystal display.

Stability improvement of carboxymethyl cellulose/chitosan complex beads by thermal treatment.

Carboxymethyl cellulose (CMC) and chitosan (CHI) are two well-known natural polymer derivatives, as such the CMC@CHI complex beads fulfill many requirements for bio-related and safety-required applications. However, poor mechanical properties of CMC@CHI beads hinder their applications. We managed to improve the beads stability by a simple thermal treatment during the bead preparation. The effects of temperature, changing from 25 °C to 75 °C, on the stability of the formed beads were investigated. The morphology, diameter, shell thickness and structure of the beads treated at different temperature were analyzed using SEM, XPS and FTIR. The mechanical test and swelling experiments showed that the thermal treatment enhanced the bead's ability to withstand pressure and swelling. The beads treated at 75 °C showed the best pressure resistance, while the beads treated at 55 °C exhibited the highest swelling capability without losing integrity. This method is convenient to implement, not only improves the stability, but also controls the swelling capacity and mechanical properties of the beads, which are important for their potential applications in adsorption and controlled release. More importantly, this work offered insights on the effects of thermal treatment on the complexation process of the two polysaccharide molecular chains.

Skeletal Muscle Fibers Inspired Polymeric Actuator by Assembly of Triblock Polymers.

Inspired by the striated structure of skeletal muscle fibers, a polymeric actuator by assembling two symmetric triblock copolymers, namely, polystyrene-b-poly(acrylic acid)-b-polystyrene (SAS) and polystyrene-b-poly(ethylene oxide)-b-polystyrene (SES) is developed. Owing to the microphase separation of the triblock copolymers and hydrogen-bonding complexation of their middle segments, the SAS/SES assembly forms a lamellar structure with alternating vitrified S and hydrogen-bonded A/E association layers. The SAS/SES strip can be actuated and operate in response to environmental pH. The contraction ratio and working density of the SAS/SES actuator are approximately 50% and 90 kJ m-3 , respectively; these values are higher than those of skeletal muscle fibers. In addition, the SAS/SES actuator shows a "catch-state", that is, it can maintain force without energy consumption, which is a feature of mollusc muscle but not skeletal muscle. This study provides a biomimetic approach for the development of artificial polymeric actuators with outstanding performance.

Genome-wide identification and expression analysis of the phosphatase 2A family in rubber tree (Hevea brasiliensis).

The protein phosphatase 2As (PP2As) play a key role in manipulating protein phosphorylation. Although a number of proteins in the latex of laticifers are phosphorylated during latex regeneration in rubber tree, information about the PP2A family is limited. In the present study, 36 members of the HbPP2A family were genome-wide identified. They were clustered into five subgroups: the subgroup HbPP2AA (4), HbPP2AB' (14), HbPP2AB'' (6), HbPP2AB55 (4), and HbPP2AC (8). The members within the same subgroup shared highly conserved gene structures and protein motifs. Most of HbPP2As possessed ethylene- and wounding-responsive cis-acting elements. The transcripts of 29 genes could be detected in latex by using published high-throughput sequencing data. Of the 29 genes, seventeen genes were significantly down-regulated while HbPP2AA1-1 and HbPP2AB55α/Bα-1were up-regulated by tapping. Of the 17 genes, 14 genes were further significantly down-regulated by ethrel application. The down-regulated expression of a large number of HbPP2As may attribute to the enhanced phosphorylation of the proteins in latex from the tapped trees and the trees treated with ethrel application.

The change from hydrophilicity to hydrophobicity of HEC/PAA complex membrane for water-in-oil emulsion separation: Thermal versus chemical treatment.

Recently, the growing environmental concerns and economic demands drive the need to develop effective solutions for the treatment of oily wastewater, especially for oil/water emulsions. In this work, hydroxyethyl cellulose (HEC) and poly(acrylic acid) (PAA) are selected to form a complex membrane on the surface of poly(ethylene terephthalate) (PET) nonwoven via layer-by-layer assembly for separation of water-in-oil emulsions. In order to obtain a hydrophobic surface, two post-treatment methods, thermally and chemically induced cross-linking, are applied to modify the hydrogen-bonded HEC/PAA complex membrane. The properties of the two treated HEC/PAA-PET membranes, including surface morphology, chemical structure, chemical composition, thermal stability, mechanical property, and membrane wettability are systematically studied and compared to each other. When the membranes are applied as oil filters to treat water-in-oil emulsions with different concentrations, both of the modified membranes show excellent separation efficiencies with a more than 99.4% rejection for all tested water-in-oil emulsions.

Enhanced biocompatibility of poly(l­lactide­co­epsilon­caprolactone) electrospun vascular grafts via self-assembly modification.

Thousands of coronary artery bypass surgeries are performed in the world every year. But there is still no alternative to autologous vessel transplantation yet. In the present study, we optimized the weight ratio of chitosan/poly(l­lactide­co­epsilon­caprolactone) (CS/PLCL) of the electrospun scaffolds, which lead to suitable mechanical properties, such as tensile strength, ultimate strain, elastic modulus and burst pressure. Besides, the scaffolds possessed the structure that mimics the native extracellular matrix. To improve the anticoagulant property of vascular grafts and avoid the use of toxic reagents, dextran sulfate was used to modify the scaffold by self-assembly method. The result of attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) demonstrated the successful modification of dextran sulfate on the scaffold. Simultaneously, modification with dextran sulfate enhanced the hydrophilicity of the scaffold. Then the degradation property of the scaffolds was evaluated by the pH value of the phosphate buffer solution (PBS) soaking solutions and mass loss of the scaffolds. Hemocompatibility test was then performed to determine the enhanced anticoagulation and antihemolysis properties of the modified scaffold. The in vitro cell viability results showed that the modified scaffold possessed favorable cell viability to the human vascular cells. Furthermore, the scaffolds were subcutaneously implanted in mice for 4 weeks. Compared to the unmodified and pure PLCL tubular scaffolds, the histological analysis indicated that the modified tubular scaffolds possessed low inflammatory response and more infiltrated cells in the scaffold. Therefore, our studies showed that dextran sulfate modified scaffold might pave the way to fabricate small-diameter vascular grafts for clinical application.

Merging metal organic framework with hollow organosilica nanoparticles as a versatile nanoplatform for cancer theranostics.

With great potential in nanomedicine, the integration of a metal organic framework (MOF) with a nanocarrier for smart and versatile cancer theranostics still seeks to expand. In this study, MOF was successfully merged with hollow mesoporous organosilica nanoparticles (HMONs) with a polydopamine (PDA) interlayer to form molecularly organic/inorganic hybridized nanocomposites (HMONs-PMOF). The well-defined nanostructure and favorable biocompatibility of HMONs-PMOF were demonstrated first. Doxorubicin hydrochloride (DOX) and indocyanine green (ICG) were separately loaded into the interior cavity of HMONs and the outer porous shell of MOF with high loading efficacy, respectively. The obtained dual drug-loaded nanocomposites (DI@HMONs-PMOF) displayed favorable photothermal properties and pH/NIR-triggered DOX release manner. Furthermore, in vitro cell experiments validated that HMONs-PMOF can efficiently deliver DOX into cancer cells. Upon entry into cancer cells, the photothermal effect of DI@HMONs-PMOF can induce the lysosome rupture, thereby facilitating the "lysosome escape" process and accelerating the DOX diffusion in the cytoplasm. Benefiting from the iron ion coordinated on PDA and ICG confined in MOF, magnetic resonance (MR) and photoacoustic (PA) dual-modality imaging were performed to verify the effective accumulation of DI@HMONs-PMOF at the tumor site. Interestingly, the results also suggested that the existence of ICG can cooperatively enhance the MR imaging capability of prepared nanocomposites. In addition, the significantly improved synergistic therapeutic efficacy was confirmed both in vitro and in vivo. Thus, our results indicated that the merged nanostructure of HMONs and MOF is promising for versatile cancer theranostics. STATEMENT OF SIGNIFICANCE: Metal organic framework (MOF) has recently emerged as a class of fascinating nanocarriers. The integration of MOF with other nanostructures can endow the new nanoformulation with collective functionality and synergistic performance that are not accessed from single-component nanostructure. Herein, we reported the successful merging of MOF and hollow mesoporous organosilica nanoparticles (HMONs) to form a hollow nanocontainer with a well-defined nanostructure. The large cavity of HMONs and highly porous network of MOF enable high drug loading efficacy. Moreover, the dual-modality magnetic resonance and photoacoustic imaging can be realized, which is also benefited from the merged nanostructure. Overall, we expected this paradigm could pave way for integrating MOF with other nanocarriers to achieve more diverse applications.

Fluorescence-enhanced bio-detection platforms obtained through controlled "step-by-step" clustering of silver nanoparticles.

Metal nanoparticle coatings are widely employed as fluorescence-enhanced platforms for high-throughput biological detection; however, complex manufacturing technologies and stringent fabrication procedures hinder their development for use in bioassays. Here, we present the preparation of fluorescence-based bioassay platforms using spray-assisted step-by-step assembly of silver nanoparticles (Ag NPs) and poly(diallyldimethylammonium chloride) (PDDA). This approach allowed us to control the density and the degree of aggregation of Ag NPs on large surfaces which are prerequisites for the development of bioassay platforms with a substantial fluorescence enhancement. After one assembly cycle (1-Ag platform) the adsorbed particles are not forming aggregates or ones composed of very few particles which, as expected, led to poor fluorescence enhancement (1.1) for cyanine 5. Further assembly steps induce the clustering of Ag NPs by multiple electrostatic interactions between PDDA and Ag NPs and thus increase the number of nanoparticles per aggregate in a controlled way. We observed that the nanoparticle island growth takes place first mainly in the plane (2D) and then in the plane and in the third dimension and that the aggregate morphology (2D versus 3D) strongly affects the plasmonic fluorescence enhancement of the fluorescent dye. A substantial fluorescence enhancement (12.3) was measured for a Ag NP platform obtained after twelve assembly cycles. This result is within the ballpark of values reported in the literature for bioassay platforms using metal nanoparticles and opens the route towards the preparation of fluorescence-based bioassay platforms on the large scale.

A unique behavior of water drops induced by low-density polyethylene surface with a sharp wettability transition.

A low-density polyethylene (LDPE) surface with a sharp wettability gradient and high hysteresis was prepared, on which a unique behavior of water drops was found. The water contact angle of one water drop on the less hydrophobic region was larger than that on the more hydrophobic end, which was much different from the general phenomenon. The unique behavior is believed to be induced by the high hysteresis of the LDPE surface and the sharp change in wettability. The driving and hysteresis forces acting on the water drops were calculated and analyzed in detail. The reasons resulting to such a unique phenomenon were further explained.

Flexible fibers wet-spun from formic acid modified chitosan.

The rigidity and low strain of chitosan fibers hindered their broader utility for biomedical applications. In present work, formic acid was employed as an efficient modifier for chitosan to prepare flexible fibers wet-spun from the formic acid modified chitosan solution. The formation of amide linkages between chitosan and formic acid was confirmed by FTIR, (13)C NMR, (1)H NMR and XRD measurements. The degree of formylation evaluated by (1)H NMR spectra was varied from 14.1% to 37.2% as a function of the reaction temperature. The results of the mechanical properties showed that the as-spun fibers exhibited an enhanced ductility with a maximum elongation at break of 21.7% compared with that spun from the chitosan dissolved in diluted acetic acid. The novel flexible chitosan fibers were anticipated to be used as comfortable wound dressing and bandages in biomedical fields.

Mechanical wounding-induced laticifer differentiation in rubber tree: An indicative role of dehydration, hydrogen peroxide, and jasmonates.

The secondary laticifer in the secondary phloem of rubber tree are a specific tissue differentiating from vascular cambia. The number of the secondary laticifers is closely related to the rubber productivity of Hevea. Factors involved in the mechanical wounding-induced laticifer differentiation were analyzed by using paraffin section, gas chromatography-mass spectrometry (GC-MS), and Northern-blot techniques. Dehydration of the wounded bark tissues triggered a burst of hydrogen peroxide, abscisic acid, and jasmonates and up-regulated the expression of HbAOSa, which was associated with the secondary laticifer differentiation strictly limited to the wounded area. Application of exogenous hydrogen peroxide, methyl jasmonate, and polyethylene glycol 6000 (PEG6000) could induce the secondary laticifer differentiation, respectively. Moreover, 6-Benzylaminopurine, a synthetic cytokinin, enhanced the methyl jasmonate-induced secondary laticifer differentiation. However, the dehydration-induced secondary laticifer differentiation was inhibited by exogenous abscisic acid. Diphenyleneiodonium chloride (DPI), a specific inhibitor of NADPH oxidase, was effective in inhibiting the accumulation of hydrogen peroxide as well as of jasmonates upon dehydration. It blocked the dehydration-induced but not the methyl jasmonate-induced secondary laticifer differentiation. The results suggested a stress signal pathway mediating the wound-induced secondary laticifer differentiation in rubber tree.

Molecular and biochemical characterization of a cyanogenic ß-glucosidase in the inner bark tissues of rubber tree (Hevea brasiliensis Muell. Arg.).

Tapping causes the loss of large amounts of latex from laticifers and subsequently enhances latex regeneration, a high carbon- and nitrogen-cost activity in rubber tree. It is suggested that a 67 kDa protein associated with protein-storing cells in the inner bark tissues of rubber tree plays an important role in meeting the nitrogen demand for latex regeneration. Here, the 67 kDa protein was further characterized by a combination of cell biological, molecular biological and biochemical techniques. Immunogold labeling showed that the 67 kDa protein was specifically localized in the central vacuole of protein-storing cells. A full-length cDNA, referred to as HbVSP1, was cloned. The HbVSP1 contained a 1584 bp open reading frame encoding a protein of 527 amino acids. The putative protein HbVSP1 shared high identity with the P66 protein from rubber tree and proteins of the linamarase, and bg1A from cassava (Manihot esculenta). HbVSP1 contained the active site sequences of ß-glucosidase, TFNEP and I/VTENG. In vitro analysis showed that the 67 kDa protein exhibited the activity of both ß-glucosidase and linamarase and was thus characterized as a cyanogenic ß-glucosidase. Proteins immuno-related to the 67 kDa protein were present in leaves and lutoids of laticifers. Tapping down-regulated the expression of HbVSP1, but up-regulated the expression of genes encoding the key enzymes for rubber biosynthesis, while the effect of resting from tapping was the reverse. Taken together, the results suggest that the 67 kDa protein is a vacuole-localized cyanogenic ß-glucosidase encoded by HbVSP1 and may have a role in nitrogen storage in inner bark tissues of trunk during the leafless periods when rubber tree is rested from tapping.

MYC genes with differential responses to tapping, mechanical wounding, ethrel and methyl jasmonate in laticifers of rubber tree (Hevea brasiliensis Muell. Arg.).

MYC2 transcription factor is a key component of the core module COI1-JAZ-MYC2 of jasmonate signaling in Arabidopsis, but the MYC transcription factor (s) associated with jasmonate signaling in jasmonate-responsive laticifer cells remains to be identified. Two full-length cDNAs, designated HblMYC1 and HblMYC2, were isolated from laticifer cells in Hevea brasiliensis by the method of RACE. HblMYC1 contained 1431bp ORF encoding a putative protein of 476 amino acids while HblMYC2 contained 1428bp ORF encoding a putative protein of 475 amino acids. Bioinformatic analysis showed that the putative proteins, HblMYC1 and HblMYC2, possessed a bHLH domain and were most related to the MYC2 among the selected 27 MYC members with identified functions in Arabidopsis. In addition to the presence of cis-regulatory elements involving jasmonate responsiveness in the promoter regions of HblMYC1 and HblMYC2, the abscisic acid-, salicylic acid- and gibberellin-responsive elements were found in the promoter region of HblMYC1. Transcripts of HblMYC1 and HblMYC2 were most abundant in latex, relatively low in male flowers and nearly undetected in bark tissues and roots by real-time RT-PCR analysis. Regular tapping, mechanical wounding, and ethrel remarkably up-regulated HblMYC1 expression, but had little effect on the expression of HblMYC2 in laticifer cells. Successive tapping, however, significantly down-regulated the expression of HblMYC2 while up-regulating the expression of HblMYC1. The HblMYC2 expression took a mutual ebb and flow relationship with the HblMYC1 expression upon treatment with methyl jasmonate. Characterization of HblMYC1 and HblMYC2 will contribute to the understanding of jasmonate signaling in laticifiers, a kind of specialized tissue for natural rubber biosynthesis in Hevea brasiliensis.