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The TGA transcription factors are known to modulate the biosynthesis of secondary metabolites in plants. However, their regulatory function in natural rubber (NR) biosynthesis was not revealed in the rubber tree (Hevea brasiliensis). Here, 14 genes encoding TGA transcription factors (name HbTGA1-HbTGA14) were identified in the rubber tree. HbTGAs were differentially expressed in different tissues. HbTGA1 was expressed at its highest level in latex. We found specific in vitro and in vivo binding of the HbTGA1 protein with promoters of multiple NR biosynthesis genes (HbHMGS2, HbHMGR2, HbCPT6, HbCPT8, and HbSRPP2). The activation of the promoters of HbHMGS2 and HbCPT6 was significantly suppressed by HbTGA1, while the activities of promoters of HbHMGR2, HbCPT8, and HbSRPP2 were increased by HbTGA1. The promoter activities of HbHMGS2, HbHMGR2, HbCPT6, HbCPT8, and HbSRPP2 were significantly increased by HbTGA1 under jasmonate stress, while the promoter activities of HbHMGS2, HbHMGR2, HbCPT6, HbCPT8, and HbSRPP2 were also significantly increased by HbTGA1 under salicylic acid stress. The present study provides insights into the role of TGA transcription factors in regulating the expression of NR biosynthesis genes from H. brasiliensis [ABSTRACT FROM AUTHOR]

The bending performance of wood is important for its application in furniture, and it is one of the criteria used to assess the suitability of a particular wood species for furniture. In this context, the steam-bending and surface roughness characteristics of four forest plantation wood species were evaluated. One batch of wood specimens were subjected to both surface roughness experiments using the stylus and toluene spread methods, while another batch of the wood specimens were subjected to steaming, clamped, and bent using a circular shape mold. The instantaneous spring-back was measured after 10 days, while the springback over time was measured from days 15 to 65. The surface roughness experiments showed that the Hevea brasiliensis had the lowest surface roughness, followed by the Eucalyptus pellita, Acacia mangium, and finally Revotropix paulownia. In terms of the bending performance, it was found that only the H. brasiliensis achieved the threshold 95% satisfactory level based on visual ranking. Furthermore, the wood species also recorded the lowest spring-back, both instantaneous and over-time, to register the best bending performance. On the other hand, R. paulownia had the worst bending performance, primarily due to its low density. [ABSTRACT FROM AUTHOR]

Hevea brasiliensis wood becomes residue at plantations in Malaysia. In this study, these residues were reinforced into silicone rubber to produce a new soft biocomposite (Hevea brasiliensis-silicone biocomposite). The newly introduced soft biocomposite has potential for use in cushioning and sealing applications. The specimens were prepared with five different compositions (0 wt%, 4 wt%, 8 wt%, 12 wt%, and 16 wt% fiber content). Tensile tests were conducted according to ASTM D412 (2008) to assess the mechanical properties. Morphological characteristics were analyzed from the fractured surface of specimens. Stress-stretch data was used to quantify the non-linear tensile behavior, which was based on Neo-Hookean, Mooney-Rivlin, and Ogden hyperelastic constitutive equations. An increase in fiber content improved the modulus of silicone rubber. However, it reduced the flexibility and elastic properties of the silicone rubber biocomposite. The increasing material constant values supported these findings. The hyperelastic models accurately represented the behavior of the Hevea brasiliensis-silicone biocomposite. This study contributes knowledge towards a better understanding of the mechanical behavior of Hevea brasiliensis-silicone biocomposites. [ABSTRACT FROM AUTHOR]

Biomass models are key tools for estimating carbon in agroecosystems. This research was conducted in Caquetá, Colombia, in plantations and agroforestry systems. A total of 41 trees of Hevea brasiliensis and 40 of Theobroma grandiflorum were sampled to estimate the above-ground biomass (Ab); and 19 and 12 trees, respectively, were excavated to estimate the below-ground biomass (Bb). The models were adjusted based on the determination coefficient (R2), the adjusted R2, and Akaike's and the Bayesian information criteria. The recommended models for Ab in H. brasiliensis and T. grandiflorum were Ln(Ab)=-2.99+2.72*Ln(DBH) and Ln(Ab)=-2.59+2.48*Ln(D30), respectively (Ab: kg.tree-1; DBH: diameter at breast height in cm; D30: trunk diameter at a 30 cm height). Additionally, models based on diameter and height were developed, as well as others based on the crown area. These models constitute an advancement in improving estimations of biomass and carbon, thus reaching Tier 2 in research and mitigation projects. [ABSTRACT FROM AUTHOR]

Natural rubber latex (NRL) is a polymer (blend) extracted from the milky sap of para rubber trees. Due to being a natural biopolymer, NRL contains various proteins that may be allergenic to humans when in skin contact. Attempts have been made to use deproteinized natural rubber (DPNR) instead of impure NRL, and the final properties of these two types of rubber tend to differ. Thus, the correlations between their chemistry and properties are of focal interest in this work. DPNR was prepared by incubating NRL with urea, followed by aqueous washing/centrifugation. The physical, mechanical, and dynamic properties of incubated NRL before and after washing/centrifugation were examined to distinguish its influences from those of incubation with urea. According to the findings, the proteins, phospholipids, and chain entanglements were responsible for natural polymer networks formed in the NR. Although the proteins were largely removed from the latex by incubation, the properties of high ammonia natural rubber (HANR) were still maintained in its DPNR form, showing that other network linkages dominated over those contributed by the proteins. In the incubated latex, the naturally occurring linkages were consistently reduced with the number of wash cycles. [ABSTRACT FROM AUTHOR]

Budding master stock of an elite clone- RRIT251 (a high latex yield clone) of para rubber (Hevea brasiliensis), and root stock of RRIM600 (a drought tolerant clone) were selected as initial plant materials. Arbuscular mycorrhizal fungi (AMF) were chosen for inoculation (+AMF). Both +AMF and non-inoculated (‒AMF) soils were kept for 30 d, and subsequently subjected to water deficit (WD) conditions through water withholding for 14 d (11.45% soil water content). Root colonization and frequency percentage of AMF were observed only in the AMF-inoculated plants. AMF colonization was reflected through increased total phosphorous content in the leaves (0.52 mg g−1 DW) and it correlated positively with number of roots (r = 0.95). Under drought stress, enrichment in free proline (45.14 µmol g−1 FW) and total soluble sugar content (211.7 mg g−1 DW) in AMF-inoculated plants functioned as major osmolytes for the maintenance of cellular osmotic potential. This led to retention of the photosynthetic pigments, chlorophyll a fluorescence (Fv/Fm and ΦPSII), net photosynthetic rate (Pn), and stomatal closure. In summary, physiological and biochemical changes in AMF inoculated plants under WD conditions act as an adaptive strategy for the maintenance of overall growth performances in terms of root fresh weight, root dry weight, shoot height, number of leaves, shoot fresh weight and shoot dry weight. The study concludes that AMF inoculation in para rubber improves its adaptation to the natural ecosystem, especially in the dry season. Thus, AMF inoculated master stocks of para rubber should further be tested in the multi-location field trials to validate the hypothesis of rapid adaptation to the natural ecosystem, especially in the rainfed regions. [ABSTRACT FROM AUTHOR]

The dimensional instability of rubberwood [Hevea brasiliensis (Willd. ex A. Juss.) Müll. Arg.] is one of the major drawbacks that limits its utilization. Therefore, treatment is needed to improve these properties. Hydrothermal treatment in different buffered media is one of the techniques that improve its dimensional stability. The physical properties of hydrothermally treated rubberwood in different buffered media (pH 4, 6, 8, 10) and tap water (pH 7.43) with different temperatures (160 °C, 180 °C and 200 °C) were studied. In this study, physical properties such as equilibrium moisture content (EMC), density (ρ), mass loss (ML), water absorption (WA), volumetric swelling coefficient (VSC), thickness swelling (TS) and anti-swelling efficiency (ASE) were investigated for both treated and untreated specimens. Both the buffered media and temperature significantly affected the physical properties. The results indicated that the EMC (%), ρ (kg/m3), ML (%), VSC (%), TS (%) of treated rubberwood samples reduced as the treatment temperature increased. With the exception of WA (%), as WA increased when the treatment temperature increased from 160 °C to 180 °C but started to decrease when the temperature was further increased to 200 °C. The research study also exhibited that hydrothermal treatment using buffered media at different temperatures enhanced the dimensional stability of the treated samples. Alkaline media gave the best results on the physical properties compared to other treatment medias. [ABSTRACT FROM AUTHOR]

Waste rubber bark abundant in phenolics can be used to produce an adsorbent for the enrichment and determination of tetracycline. Fe 3 O 4 magnetic nanoparticles (Fe 3 O 4 MNPs) coated with naturally extracted phenolics from waste rubber bark were synthesized for the first time by ultrasound combined with a continuous flow approach. The production of Fe 3 O 4 MNPs with effective contact surface areas (45.3 m2 g−1) was employed as a novel attractive sorbent in magnetic solid phase extraction (MSPE) to selectively preconcentrate oxytetracycline, tetracycline, chlortetracycline, and doxycycline before HPLC-UV analysis. This MSPE-HPLC exhibited wide linear ranges (14.0–260.0 μg kg−1), with low limits of detection (10.0 μg kg−1) and quantitation (14.0–20.0 μg kg−1), and was successfully applied to quantify tetracycline residues in honey samples, with recoveries ranging from 81.3 % to 117.9 %. This method offers a potential alternative for determining tetracycline in food with a high enrichment factor, high precision, and more effective accuracy, selectivity, and sensitivity. [Display omitted] • Natural reagents from waste rubber bark enhanced the adsorption capacity of Fe 3 O 4. • Synergism of ultrasound-assisted continuous flow provided uniform Fe 3 O 4 MNPs. • Natural phenolic-coated Fe 3 O 4 MNPs selectively adsorbed tetracycline. • MSPE using novel Fe 3 O 4 MNPs demonstrated high tetracycline extraction efficiency. • MSPE-HPLC exhibited lower LOD and LOQ values than tetracycline MRLs in honey. [ABSTRACT FROM AUTHOR]

Natural rubber originates from the coagulation of rubber particles (RP) from Hevea brasiliensis latex. The size distribution of Hevea RP is bimodal with the presence of small rubber particles (SRP) and large rubber particles (LRP). This study aims at getting a better understanding of the early coagulation steps of Hevea RP taking into account the particle size. SRP and LRP were obtained by centrifugation of freshly tapped ammonia-free latex from RRIM600 clone. Size and zeta potential measurements showed that both RP fractions were efficiently separated and stable in basic buffer. SRP and LRP dispersions were placed in a Langmuir trough and RP were let to adsorb at the air-liquid interface to form interfacial films. Surface tension and ellipsometry indicate that the formation kinetics and the stabilization of the film at the air-liquid interface are faster for SRP than LRP. Moreover, the arrangement of RP at the interface differs between SRP and LRP, as shown by Brewster angle microscopy, atomic force microscopy and confocal laser scanning microscopy. First, the RP membrane and cis -1,4-polyisoprene core spread at the air-liquid interface before clustering. Then, while the SRP fuse, the LRP keep their structure in individual particles in floating aggregate. The role of the non-isoprene molecules on the different organization of SRP and LRP films is discussed, the one of the two major RP proteins, SRPP1 (Small Rubber Particle Protein) and Rubber Elongation Factor (REF1) in the early coagulation steps. • Formation kinetics and stabilization of fluid films are faster for SRP than LRP. • Rubber particle size influences the film organization at BAM and AFM scales. • LRP membrane is partially destabilized in fluid film but LRP topology is preserved. • Interface air/liquid destructures SRP and promotes first step of coagulation. • CLSM highlights the repartition of lipids of the rubber particle membrane. [ABSTRACT FROM AUTHOR]

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The cultivation of elite latex-timber clones that exhibit both enhanced NR and wood production has become a key objective in current Hevea brasiliensis breeding programs. The girth and dry rubber yield (DRY) are two crucial indicators for evaluating the latex-timber characteristics of Hevea trees. However, the quantitative trait locus (QTL) and candidate genes identified for these traits are still limited. Here, a genome-wide association study (GWAS) was performed in a Whickham germplasm offspring to identify genetic variants associated with girth and DRY. Girth and DRY phenotypes were measured for three consecutive years. Meanwhile, a total of 7835,736 high-confidence SNPs were identified from 218 Hevea accessions. Remarkably, the population exhibited a high level of genetic diversity, coupled with a rapid decline in linkage disequilibrium, and was roughly grouped into three subgroups by population structure analysis. A total of 17 and 76 SNPs, respectively, correlated significantly with girth DRY, and corresponded to 31 and 284candidate genes for girth and DRY. To further assess the candidates, gene expression analyses were performed separately on four types of Hevea tree tissues and two distinct groups exhibiting notable girth or DRY phenotypic differences. Eventually, a cullin protein and an iridoid oxidase protein were identified as prospective girth regulators, whereas two chloroplast thylakoid membrane proteins and an auxin-repressed protein were implicated in shaping the performance of DRY. These findings contribute to a deeper understanding of the genetic foundations of girth and DRY, as well as molecular-assisted breeding of latex-timber rubber clones. [Display omitted] • Genome-wide association study on 218 offspring accessions of Hevea Wickham germplasm to identify girth and rubber yield QTLs. • Substantial genetic diversity observed in this progeny population. • 17 and 76 significant SNPs associated with girth and rubber yield, respectively. • The cullin and iridoid oxidase identified as promising candidates for regulating girth development. • The chloroplast thylakoid membrane and auxin-repressed proteins identified as candidates affecting rubber yield. [ABSTRACT FROM AUTHOR]

Taraxacum kok - saghyz (TKS) has been investigated as an alternative rubber crop due to its comparability in rubber quality to the Para rubber tree, Hevea brasiliensis. However, the yield of natural rubber from TKS is relatively low, necessitating the development of effective strategies to enhance its production. In this study, we report that the rubber production of TKS was increased by about 40% through foliar application of a natural lipid, lyso-PE. To better understand the effect of lyso-PE on the biosynthesis of natural rubber, we performed transcriptome analysis in TKS latex. We identified 1258 differentially expressed genes in TKS latex after lyso-PE treatment, and through multiple analyses, we found that lyso-PE mediates genetic modulations in various metabolic pathways related to resistance response and secondary metabolite metabolisms. Among the natural rubber biosynthesis pathways, the mevalonate pathway leading to the production of a monomer (isopentenyl pyrophosphate) and the biosynthesis pathway of the initiators (geranyl pyrophosphate and farnesyl pyrophosphate) of rubber polymerization, as well as the expression of SRPP genes, were stimulated by lyso-PE treatment. This study with TKS root latex provides a novel and relatively straightforward method to enhance the yield of natural rubber through the exogenous application of a natural lipid, as well as fundamental knowledge for future research on improving natural rubber biosynthesis in TKS. • Foliar application of LPE enhanced natural rubber yield in Taraxacum kok - saghyz. • LPE causes metabolic adjustment and genetic modulations in rubber biosynthesis. • Transcriptome analysis identified 1258 DEGs in TKS latex treated with LPE. • This study provides a new strategy to increase natural rubber yield with a natural lipid. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (AuNPs) have shown interesting properties and specific biofunctions, providing benefits and new opportunities for controlled release systems. In this research, we demonstrated the use of natural rubber latex (NRL) from Hevea brasiliensis as a carrier of AuNPs and the antibiotic metronidazole (MET). We prepared AuNP-MET-NRL and characterized by physicochemical, biological and in vitro release assays. The effect of AuNPs on MET release was evaluated using UV–Vis and Laser-Induced Breakdown Spectroscopy (LIBS) techniques. AuNPs synthesized by Turkevich and Frens method resulted in a spherical shape with diameters of 34.8 ± 5.5 nm. We verified that there was no emergence or disappearance of new vibrational bands. Qualitatively and quantitatively, we showed that the MET crystals dispersed throughout the NRL. The Young's modulus and elongation values at dressing rupture were in the range appropriate for human skin application. 64.70% of the AuNP-MET complex was released within 100 h, exhibiting a second-order exponential release profile. The LIBS technique allowed monitoring of the AuNP release, indicating the Au emission peak reduction at 267.57 nm over time. Moreover, the dressing displayed an excellent hemocompatibility and fibroblast cell viability. These results demonstrated that the AuNP-MET-NRL wound dressing is a promising approach for dermal applications. • A wound dressing was developed using AuNPs and metronidazole loaded into NRL. • The reduction of the Au signal verified by LIBS proved to be an efficient approach in the identification of AuNP released • 64.7% of the AuNPs-metronidazole complex was released by the polymeric matrix • Wound dressing was biocompatible in hemolytic tests, beyond to contributing to the fibroblasts proliferation. [ABSTRACT FROM AUTHOR]

The WUSCHEL-related homeobox (WOX) proteins are widely distributed in plants and play important regulatory roles in growth and development processes such as embryonic development and organ development. Here, series of bioinformatics methods were utilized to unravel the structural basis and genetic hierarchy of WOX genes, followed by regulation of the WOX genes in four Euphorbiaceae species. A genome-wide survey identified 59 WOX genes in Hevea brasiliensis (H. brasiliensis : 20 genes), Jatropha curcas (J. curcas : 10 genes), Manihot esculenta (M. esculenta : 18 genes), and Ricinus communis (R. communis : 11 genes). The phylogenetic analysis revealed that these WOX members could be clustered into three close proximal clades, such as namely ancient, intermediate and modern/WUS clades. In addition, gene structures and conserved motif analyses further validated that the WOX genes were conserved within each phylogenetic clade. These results suggested the relationships among WOX members in the four Euphorbiaceae species. We found that WOX genes in H. brasiliensis and M. esculenta exhibit close genetic relationship with J. curcas and R. communis. Additionally, the presence of various cis -acting regulatory elements in the promoter of J. curcas WOX genes (JcWOXs) reflected distinct functions. These speculations were further validated with the differential expression profiles of various JcWOXs in seeds, reflecting the importance of two JcWOX genes (JcWOX6 and JcWOX13) during plant growth and development. Our quantitative real-time PCR (qRT-PCR) analysis demonstrated that the JcWOX11 gene plays an indispensable role in regulating plant callus. Taken together, the present study reports the comprehensive characteristics and relationships of WOX genes in four Euphorbiaceae species, providing new insights into their characterization. [ABSTRACT FROM AUTHOR]

Guayule (Parthenium argentatum Gray) is a perennial desert shrub currently under investigation as a viable commercial alternative to the Pará rubber tree (Hevea brasiliensis), the traditional source of natural rubber. Previous studies on guayule have shown a close association between morphological traits or biomass and rubber content. We collected multispectral and RGB-derived Structure-from-motion (SfM) data using an unmanned aircraft system (UAS; drone) to determine if incorporating both high-resolution normalized difference vegetation index (NDVI; an indicator of plant health) and canopy height (CH) information could support model predictions of crop productivity. Ground-truth resource allocation in guayule was measured at four elevations (i.e., tiers) along the crop's vertical profile using both traditional biomass measurement techniques and a novel volumetric measurement technique. Multiple linear regression models estimating fresh weight (FW), dry weight (DW), fresh volume (FV), fresh-weight-density (FWD), and dry-weight-density (DWD) were developed and their performance compared. Of the crop productivity measures considered, a model predicting FWD (i.e., the fresh weight of plant material adjusted by its freshly harvested volume) and incorporating NDVI, CH, NDVI:CH interaction, and tier parameters reported the lowest mean absolute percentage error (MAPE) between field measurements and predictions, ranging from 9 to 13%. A reduced FWD model incorporating only NDVI and tier parameters was developed to explore the scalability of model predictions to medium spatial resolutions with Sentinel-2 satellite data. Across all UAS surveys and corresponding satellite imagery compared, MAPE between FWD model predictions for UAS and satellite data were below 3% irrespective of soil pixel influence. [ABSTRACT FROM AUTHOR]

Background: Rigidoporus microporus causes white root disease, which is one of the most harmful diseases in rubber trees in Thailand. The objectives of this study were to determine the efficacy of T. asperellum NST-009 and its antifungal metabolite in inhibiting R. microporus mycelial development and efficacy of T. asperellum NST-009 in controlling white root disease of rubber trees in an open-field house experiment. Methods: Four native strains of T. asperellum from Nakhon Si Thammarat Province and a commercial strain of Thailand were used in this study. This study was conducted at Agricultural Microbial Production and Service Center, Walailak University, Nakhon Si Thammarat, Thailand, during the period 2017-2020. Result: T. asperellum NST-009 significantly inhibited R. microporus mycelial growth by 77.07% in vitro and its antifungal metabolite from the culture filtrate of T. asperellum NST-009 inhibited mycelial growth by 92.31%. T. asperellum NST-009 reduced the disease severity index by 76.38% in the open-field house experiment compared to the inoculated control. Furthermore, T. asperellum NST-009 was found to survive in rhizosphere soil at 4.50105 CFU/g soil and colonized the roots at 100.00%. [ABSTRACT FROM AUTHOR]

Hevea brasiliensis is an economically important tree species that provides the only commercial source of natural rubber. The replacement of the CaMV35S promoter by endogenous polyubiquitin promoters may be a viable way to improve the genetic transformation of this species. However, no endogenous polyubiquitin promoters in Hevea have been reported yet. Here, we identified three Hevea polyubiquitin genes HbUBI10.1, HbUBI10.2 and HbUBI10.3, which encode ubiquitin monomers having nearly identical amino acid sequences to that of AtUBQ10. The genomic fragments upstream of these HbUBI genes, including the signature leading introns, were amplified as putative HbUBI promoters. In silico analysis showed that a number of cis-acting elements which are conserved within strong constitutive polyubiquitin promoters were presented in these HbUBI promoters. Transcriptomic data revealed that HbUBI10.1 and HbUBI10.2 had a constitutive expression in Hevea plants. Semi-quantitative RT-PCR showed that these three HbUBI genes were expressed higher than the GUS gene driven by CaMV35S in transgenic Hevea leaves. All three HbUBI promoters exhibited the capability to direct GFP expression in both transient and stable transformation assays, although they produced lower protoplast transformation efficiencies than the CaMV35S promoter. These HbUBI promoters will expand the availability of promoters for driving the transgene expression in Hevea genetic engineering. [ABSTRACT FROM AUTHOR]

Rapidly developing droughts, including flash droughts, have occurred frequently in recent years, causing significant damage to agroforestry ecosystems, and they are expected to increase in the future due to global warming. The artificial forest area in China is the largest in the world, and its carbon budget is crucial to the global carbon sink. As the most prominent plantation plant in the tropics, the rubber (Hevea brasiliensis (Willd. ex A. Juss.) Muell. Arg.) ecosystem not only has important economic significance, but also has the potential to be a major natural carbon sink in hot areas. Frequent drought events have a significant impact on rubber ecosystem productivity, yet there have been few reports on the vulnerability of rubber productivity to drought. The objective of this study is to evaluate the vulnerability of rubber ecosystem gross primary production (GPP) to short-term flash drought (STFD) in Hainan Island, utilizing the localized EC-LUE model (eddy covariance–light use efficiency) validated by flux tower observations as the research tool to conduct the scenario simulations which defined by standard relative humidity index (SRHI), in a total of 96 scenarios (timing × intensity). The results show that, in terms of time, the rubber ecosystem in Hainan Island has the highest vulnerability to STFD during the early rainy season and the lowest at the end of the rainy season. From the dry season to the rainy season, the impact of STFD gradually extends to the northeast. Spatially, the vulnerability of the northern island is higher than that of the southern island and that of the western part is higher than that of eastern Hainan Island. With the increase in STFD intensity, the spatial distribution center of the vulnerability of rubber ecosystem GPP in Hainan Island gradually moves southward. The spatiotemporal pattern of the vulnerability of the rubber ecosystem GPP to STFD over Hainan Island plotted by this study is expected to provide decision makers with more accurate information on the prevention and control of drought disaster risk in rubber ecosystems. [ABSTRACT FROM AUTHOR]

Members of the AT-hook motif nuclear localized (AHL) family contain diverse but poorly understood biological functions. We identified 371 AHLs in 20 land plants, varying from the early diverging lycophyte Selagineila moellendorfi to a variety of higher plants. The AHLs were divided into two clades (Clade-A and Clade-B) with three different types (Type-I, Type-II, and Type-III AHLs). The divergence between Clade-A and Clade-B likely occurred before the separation of S. moellendorfi from the vascular plant lineages. Members of the AHLs family expanded with the specific whole-genome duplication (WGD)/segmental duplication in some genomes, such as Hevea brasiliensis. The ortholog (Vf00G1914/Amo018442) exhibited opposite expression patterns between two Vernicia species (V. fordii and V. montana), indicating that it was implicated in resistance to Fusarium wilt disease. The expression of Vf09G2138 exhibited a negative correlation with lipid biosynthesis in V. fordii seeds during different stages of development, suggesting that this gene might repress the seed oil accumulation. The core AT-hook motif and PPC domain were responsible for guiding the localization of AHL in the nucleus. This study helps us to understand the evolution of AHLs in multiple plants, further highlight their functions during V. fordii seed development and response to Fusarium wilt disease. [ABSTRACT FROM AUTHOR]

Rubber tree plantations (Hevea brasiliensis) cover large areas in the tropics. In historical producing regions like South Thailand, rubber has been planted by smallholders for three successive rotations lasting a total of 75 years. Despite possible consequences on topsoil, the long‐term impacts of repeated rubber plantations on soil quality remain unknown. This study aims to better understand how various factors linked to long‐term rubber land use and land use change affect topsoil physico‐chemical properties and soil organic carbon (SOC) thermal stability. We focus on the effects of three factors: i. deforestation (change from forest to first rubber plantation); ii. the age of the rubber stand (immature vs. mature); and iii. long‐term rubber cultivation (first, second or third successive rotation) over a chronosequence in farmers plots. Our results show that soil was deeply degraded after deforestation to a rubber plantation. Long‐term rubber cultivation is also detrimental for the soil and has a more negative impact on soil physico‐chemical properties and carbon dynamics, than the age of the rubber stand (e.g., on average, decrease of 50% of SOC content between forest and third rotation). At the third rotation, after 50 years of rubber cultivation, the quality of the 0–10 cm soil layer was very low, with an increase in SOC thermal stability. At this stage, logging practices upset the sustainability of the system. These impacts could be limited by less destructive practices during planting. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the production and properties of mixed pellets made from rubberwood (Hevea brasiliensis Muell. Arg) and refuse-derived fuel (RDF) waste with no added binder. Three different conditions of mixed pellets were developed to compare their chemical and physical properties to rubberwood pellets. The produced samples were subjected to both ultimate and proximate analyses. The contents of C, H, N, S, and Cl significantly increased with the increasing amount of refuse-derived fuel in the samples, resulting in reduction of the volatile matter. The mechanical durability of the pellet samples ranged between an average value of 98 and 99%. Mixed pellets containing 50% of rubberwood and 50% of refuse-derived fuel have improved heating values by 22.21% compared to rubberwood pellets. Moreover, mixed pellets having 50% of wood and 50% of refuse-derived fuel had the highest density and the highest energy compared to the other samples. Based on the findings of this study, it appears that the manufactured mixed pellets have the potential to be used as high-energy fuel. [ABSTRACT FROM AUTHOR]

Calcium (Ca2+) signaling is one of the earliest factors to coordinate plant adaptive responses. As direct sensors and activators of Ca2+ signals, calcium-dependent protein kinases (CDPKs) were reported to be widely involved in regulating different biotic and abiotic stress stimuli. In this study, 32 Hevea brasiliensis CDPK (HbCDPK) genes were predicted and classified into four subgroups. Among them, the full-length coding sequences of 28 HbCDPK genes were confirmed by RT-PCR and verified by sequencing. Putative cis-elements assay in the promoters of HbCDPKs showed that most of the HbCDPK genes contained gibberellic acid-responsive element (GARE), abscisic acid-responsive element (ABRE), salicylic acid-responsive element (SARE), defense and stress responsive element (TC-rich repeats) and low-temperature response element (LTR), which could be activated by different biotic and abiotic stresses. Real-time PCR analysis indicated that 28 HbCDPK genes respond to infection of pathogenic fungi and a variety of phytohormones. Subcellular localization was observed with most HbCDPKs located in cell membrane, cytoplasm or organelles. Some HbCDPKs were confirmed to cause reactive oxygen species (ROS) production and accumulation in rubber tree mesophyll protoplast directly. HbCDPK 5 was strongly induced by the inoculation with Colletotrichum gloeosporioides and was chosen for further analysis. HbCDPK5 localized to the cell membrane and cytoplasm, and obviously regulated the accumulation of ROS in rubber tree mesophyll protoplast. Overexpression of HbCDPK5 in Arabidopsis enhanced the resistance to Botrytis cinerea. These results indicate that rubber tree CDPK genes play important roles in plant disease resistance. [ABSTRACT FROM AUTHOR]

[Objective]The genetic characteristics and genetic analysis of parents and hybrids were analyzed in terms of phenotypic traits and molecular markers, which provided reference for the selection of parental combinations and the difference analysis of hybrids. [Method] The genetic characteristics and genetic diversity of 3 5 Hevea hybrid progeny populations were studied using phenotypic traits and SSR molecular markers. [Result] The coefficient of variation of 32 phenotypic traits was 32. 59%, the maximum variation coeffi cient of the pulvinus largening was 60. 90%, and the minimum variation coefficient of the petiolule groove was 0. The diversity index ranged from 3. 22 to 3. 53, with an average of 3. 49. Heterosis analysis showed that F1 hybrids had strong heterosis in girth, annual average increase and yield, which were 101. 2%, 117. 2% and 95. 38%, respectively. Among the 35 F1 hybrids, the material of A38 had the highest yield and A9 had the lowest yield. In each of the four years from 2017 to 2020, the material of A22 was the largest hybrid in girth. The annual increase of 35 F 1 hybrids ranged from 5. 6 to 10. 4 cm, and the annual average girth increment ranged from 6. 7 to 8. 8 cm. According to the results of molecular marker analysis, 15 pairs of primers with good amplification effect were screened out from 104 pairs of primers. By using the genetic diversity analysis of 15 pairs of SSR marker parents and progeny populations, a total of 15 alleles were amplified with polymorphism information content (PIC) of 0. 2710 -0. 6827. Shannon's information index (I), the observed heterozygosity (H0) and expected heterozygosity (H,) were 0. 5004-1. 3459, 0. 1714-1. 0000 and 0. 3246-0. 7400, respectively. Cluster analysis using UPGMA showed that the hybrids could be divided into three groups. [Conclusion] The genetic variation and genetic diversity of hybrid progeny were analyzed to provide material and theoretical support for hybrid breeding and parental selection. [ABSTRACT FROM AUTHOR]

Brassinolide (BR) plays an important role in plant growth, development, and the adaptation adversity process. Moreover, BRI1-EMS-SUPPRESSOR 1 (BES1) genes are crucial transcription factors (TFs) in the BR signaling pathway. To realize the function of HbBES1 family is helpful to improve genetic resources for rubber tree breeding. Based on the rubber tree database, we used bioinformatics to characterize physicochemical properties, gene structure, cis-elements, and expression patterns. These results indicated that there were nine BES1 members in rubber tree, which we named HbBES1-1 to HbBES1-9 and divided into two groups (I and II) based on their genetic relationships. HbBES1 genes in the same group shared similar gene structures and motifs. Cis-acting element analysis showed that the promoter sequences of HbBES1 genes contained many regulator elements that were related to hormone and stress, indicating that HbBES1 genes might be involved in the regulation of hormone and stress signal pathways. Our analysis of tissue specificity revealed that all of the nine HbBES1 members expressed highly in branches. Gene expression profiles under different hormone treatments showed that the HbBES1 gene family was induced to varying degrees under different hormones, HbBES1-3 and HbBES1-9 were extremely induced by ethylene (ETH). These results lay the foundation for further exploration of the molecular mechanism of the BES1 gene family, especially HbBES1-3 and HbBES1-9, regulating plant stress tolerance in rubber tree. [ABSTRACT FROM AUTHOR]

The diabetic foot is characterized by the loss of foot ulcerations and sensitivity. The use of orthopedic orthosis can prevent pathological changes in the diabetic foot. The objective of this study was to characterize materials used for producing orthopedic orthosis: silicone; pre-vulcanized latex of Hevea brasiliensis; Evapod, and Podadur. The Hevea brasiliensis latex material is widely indicated in the literature for biomedical purposes. Physical–mechanical properties were determined (properties of elastic deformation, resistance, durability, lightness, energy absorption, resistance to high temperatures, and chemical composition—ASTM International). In the tensile test, the latex reached 6.02 ± 0.33 MPa, having the best performance among the other materials. In the elastic module, the Podadur stood out, with 28.2 ± 0.89 MPa, compared to silicone with 0.42 ± 0.05 MPa. The most excellent Shore A hardness material was Podadur with 58%. As for the resilience, the Podadur presented a minimum value of 22%, while latex had 63%. Silicone was the densest material, with a density of 1.48 g/cm3, and Evapod and Podadur were the lightest, respectively, at 0.22 g/cm3 and 0.42 g/cm3. Morphologically, Evapod, Podadur, and latex presented open and interconnected cells, characteristics that gave them a more significant water absorption capacity. Silicone was the only material with no empty cells in its structure. In X-ray diffraction, Evapod, Podadur, and silicone materials presented well-defined crystallographic planes, whereas amorphous behavior characterized latex. Thermogravimetry showed weight loss between 240 and 650 °C in the four materials. In the fluorescence test, the presence of metals was observed in the composition of the four materials. Among the materials studied, the Podadur was the material that stood out, with some good properties for the development of orthopedic orthosis. [ABSTRACT FROM AUTHOR]

Natural latex serum (NLS) is one of the natural rubber latex fractions from Hevea brasiliensis tree, which is formed by centrifuged serum and is composed of proteins, acids, nucleotides, salts and carbohydrates. The proteins present in NLS have demonstrated several interesting biological properties, including angiogenic, healing, osteogenic, anti-inflammatory, antimicrobial, in addition to inducing neovascularization, bone formation and osseointegration. Thus, we proposed to characterize NLS by physicochemical techniques and to investigate the biocompatibility by toxicological assays and safety test in Galleria mellonella. Infrared spectrum showed vibrational bands characteristic of amide I, II and III that are linked to the protein content, which was confirmed by the High Performance Liquid Chromatography profile and by the Electrophoresis analysis. This material did not exhibit hemolytic (rate <0.5%) and cytotoxic effects (viability >70%) and was able to enhance the proliferation of fibroblasts (>600%) after 3 days. The pronounced proliferative effect observed in fibroblast cells can be explained by the presence of the fibroblast growth factor (FGF) like protein revealed by the Western blot test. Moreover, NLS did not provoke toxic effects (survival ∼ 80%) on the G. mellonella model, indicating that it is a biocompatible and safe material. [ABSTRACT FROM AUTHOR]

The recurring growth of bacterium in newly developed resistant cells and a minimal level of bacterial infection rate are the main limiting factors of Agrobacterium-mediated transformation experiments in Hevea brasiliensis. The current study aimed to optimize crucial factors of the transformation protocol in order to obtain an efficient transformation experimental model for Hevea using cotyledonary somatic embryos as explants. Transformation conditions such as antibiotic concentration, preculture duration, Agrobacterium concentration, sonication and cocultivation conditions were analyzed using the binary vector pCAMBIA2301. Transient transformation was confirmed by GUS histochemical staining. The best transformation efficiency was observed when the explants were not cultured on a preculture medium that contained acetosyringone at a level of 100 μM. The best results were obtained using a bacterial density of 0.45 at OD 600 nm, 50 s of sonication of explants in a bacterial liquid culture and a total incubation time of 18 min in the same bacterial suspension. Transmission electron microscopical analysis confirmed the impacts of sonication on bacterial infection efficiency. Cocultivation conditions of 22 °C and 84 h of darkness were optimal for the transfer of T-DNA. Agrobacterium was eliminated with 500 mg/L of timentin, and the selection of transformants was performed using 100 mg/L of kanamycin in the selection medium. The presence of transgene was confirmed in the resistant embryos by polymerase chain reaction (PCR). The improved method of genetic transformation established in the present study will be useful for the introduction of foreign genes of interest into the Hevea genome for the breeding of this economically important plant species in the future. [ABSTRACT FROM AUTHOR]

Natural rubber is extracted from the Hevea tree, through shaving the bark. As a major raw material source for many industries especially the tyre sector, Hevea rubber clones are intensively cultivated in the tropics. The world production of Hevea rubber is almost 13.64 million metric tonnes, and the productivity is around 1200 kg ha−1. However, the field production achieved so far is still well below the theoretical yield estimated (7000–12,000 kg ha−1). Even though this is a calculated estimate, efforts can be kept live to achieve this target, because Hevea rubber is being increasingly cultivated under several suboptimal environments after the 1980s. In this era of climate change, newer biotic and abiotic stresses encounter Hevea rubber culture that demands new clones at definite intervals. Hence, like any other species, Hevea rubber breeding is a continuous process in quest of new clones achieved through exploiting new sources of genetic variation. Hevea rubber breeding is to produce high‐yielding clones with good timber value. First priority is to explore and exploit genetic variation in clones, half‐sib, full‐sib and illegitimate (open‐pollinated) seedlings, where dry rubber yield and wood volume are the target traits. Next is to maximize genetic gains per unit time, through understanding juvenile–mature correlations and to practice selection of high‐yielding genotypes at the juvenile stage. Hevea rubber had a long breeding cycle of 33 years but could be reduced to 17 years after culling non‐essential steps of deriving clones. However, this could be reduced to 10 years, if a DNA marker‐assisted selection system is applied to seedlings. This system must also ensure significant juvenile–mature correlations on yield. This is a formidable task because under given circumstances, such a correlation is almost absent. However, this can be turned into a reality through employing yield‐related DNA markers with genomic selection (GS). The impact of DNA markers linked with REF, SRPP, acetyl‐CoA acetyltransferase, HMGS, HMGR and JAZ need to be specifically evaluated. GS that aims to improve quantitative traits by using genome‐wide marker data without requiring identification of markers associated with quantitative trait loci (QTLs) of interest can be used in Hevea also. Subsequently, by a predictive model, genomic estimated breeding values (GEBVs) can be calculated for untested individuals from a 'testing population'. GS captures the total additive genetic variance with genome‐wide marker coverage and effect estimates. Therefore, selection of an individual without phenotypic data can be performed based on the individual's predicted breeding value. This review makes an assessment of the molecular markers in Hevea rubber and aims to streamline an efficient selection system to be applied onto seedlings through GS that owes a significant correlation with the mature phase. [ABSTRACT FROM AUTHOR]

Hevea brasiliensis (HB) flower particulates were filled high‐density poly ethylene (HDPE) composite was molded through a vertical injection molding process. The molded composite specimens were carried out X‐ray powder diffraction analysis and found the HB filler crystal size of 12.63 nm. The morphology of the HB/HDPE composite was analyzed through field emission scanning electron microscope and the presence of different elements was found through energy dispersive X‐ray. The HB/HDPE composite was carried out thermo gravimetric analysis, differential scanning calorimetric, and found its melting point and its degradation. The HB/HDPE composite was carried out and found its mechanical properties. The observed result suggests that the newly developed composites could be used for low‐strength applications. [ABSTRACT FROM AUTHOR]

The rubber tree, Hevea brasiliensis, is a neotropical Amazonian species. Despite its high economic value and fungi associated with native individuals, in its original area in Brazil, it has been scarcely investigated and only using culture-dependent methods. Herein, we integrated in silico approaches with novel field/experimental approaches and a case study of shotgun metagenomics and small RNA metatranscriptomics of an adult individual. Scientific literature, host fungus, and DNA databases are biased to fungal taxa, and are mainly related to rubber tree diseases and in non-native ecosystems. Metabarcoding retrieved specific phyllospheric core fungal communities of all individuals, adults, plantlets, and leaves of the same plant, unravelling hierarchical structured core mycobiomes. Basidiomycotan yeast-like fungi that display the potential to produce antifungal compounds and a complex of non-invasive ectophytic parasites (Sooty Blotch and Flyspeck fungi) co-occurred in all samples, encompassing the strictest core mycobiome. The case study of the same adult tree (previously studied using culture-dependent approach) analyzed by amplicon, shotgun metagenomics, and small RNA transcriptomics revealed a high relative abundance of insect parasite-pathogens, anaerobic fungi and a high expression of Trichoderma (a fungal genus long reported as dominant in healthy wild rubber trees), respectively. Altogether, our study unravels new and intriguing information/hypotheses of the foliar mycobiome of native H. brasiliensis, which may also occur in other native Amazonian trees. [ABSTRACT FROM AUTHOR]

This study was established to evaluate the efficiency of essential oils from tropical plants such as Cinnamomum zeylanicum, Cinnamomum rhyncophyllum and Litsea elliptica in preserving susceptible timber against a subterranean termite named Coptotermes curvignathus. Two different tests mainly the toxicity and repellent tests were conducted in five concentrations (0.5%, 1.0%, 2.0%, 3.0% and 4.0%) to observe the repellency, feeding response and mortality of the termites. A no-choice test was conducted in the laboratory to investigate the effectiveness of essential oils in protecting Hevea brasiliensis. Based on the findings, C. zeylanicum essential oil showed high antifeedant (56.2%-96.2%) and repellent (41.0%-62.0%) activities. The oil was also very effective in no-choice test with a lower percentage of wood use (3.5%-5.9%), a higher percentage of C. curvignathus mortality (90.2%-100%) and a higher visual assessment (8.9-9.2). The performance was followed by C. rhyncophyllum, while L. elliptica essential oil had the highest repellent activity at each level of concentration. The results suggested that these essential oils had beneficial activities of economic value for the development of new or latest termite control product. [ABSTRACT FROM AUTHOR]

Keywords: Hevea brasiliensis; leaf spot EN Hevea brasiliensis leaf spot 1 4 4 06/29/22 20220401 NES 220401 Rubber trees ( I Hevea brasiliensis i ) are planted on 65,545 hectares in Colombia (Minagricultura, 2021). Since September 2020, unusual leaf spots were observed on mature leaves of rubber trees (clones RRIM 600 and FX 3864), in three plantations in the Eastern Plains region. [Extracted from the article]

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Myelocytomatosis (MYC) transcription factors play a core regulator in the jasmonic acid signaling pathway, which regulates the secondary laticifer differentiation and rubber biosynthesis in rubber tree (Hevea brasiliensis). However, there are currently no reports on the MYC gene family in rubber trees, an important industrial raw material crop worldwide. In the present study, 32 HblMYCs were isolated and identified. The diversity in gene structure and presence of various cis-regulatory elements in promotors suggest that HblMYCs participate in various biological processes. Based on the expression patterns in the cambium region and laticifer in, respectively, response to coronatine (COR) and tapping, and the phylogenetic relationship with the MYCs that have been functionally identified in other plants, the HblMYC24 and HblMYC30 may be related to laticifer differentiation while the HblMYC6, HblMYC11 and HblMYC15, as well as HblMYC16 and HblMYC21, may positively regulate rubber biosynthesis. The results provide a foundation for understanding the molecular mechanism of jasmonate signaling in regulating laticifer differentiation and rubber biosynthesis in rubber tree. [ABSTRACT FROM AUTHOR]

Xylona heveae has only been isolated as an endophyte of rubber trees. In an effort to understand the genetic basis of endophytism, we compared the genome contents of X. heveae and 36 other Ascomycota with diverse lifestyles and nutritional modes. We focused on genes that are known to be important in the host-fungus interaction interface and that presumably have a role in determining the lifestyle of a fungus. We used phylogenomic data to infer the higher-level phylogenetic position of the Xylonomycetes, and mined ITS sequences to explore its taxonomic and ecological diversity. The X. heveae genome contains a low number of enzymes needed for plant cell wall degradation, suggesting that Xylona is a highly adapted specialist and likely dependent on its host for survival. The reduced repertoire of carbohydrate active enzymes could reflect an adaptation to intercellulary growth and to the avoidance of the host's immune system, suggesting that Xylona has a strictly endophytic lifestyle. Phylogenomic data resolved the position of Xylonomycetes as sister to Lecanoromycetes and Eurotiomycetes and placed the beetle-endosymbiont Symbiotaphrina as a member of this class. ITS data revealed that Trinosporium is also part of the Xylonomycetes, extending the taxonomic and ecological diversity of this group.

Low temperature is a key factor limiting the rubber plantation extending to high latitude area. Previous work has shown that cold-induced DNA demethylation was coordinated with the expression of cold-responsive (COR) genes in Hevea brasiliensis. In this work, reduced representation bisulphite sequencing analysis of H. brasiliensis showed that cold treatment induced global genomic DNA demethylation and altered the sequence contexts of methylated cytosines, but the levels of mCG methylation in transposable elements were slightly enhanced by cold treatment. Integrated analysis of the DNA methylome and transcriptome revealed 400 genes whose expression correlated with altered DNA methylation. DNA demethylation in the upstream region of gene seems to correlate with higher gene expression, whereas demethylation in the gene body has less association. Our results suggest that cold treatment globally change the genomic DNA methylation status of the rubber tree, which might coordinate reprogramming of the transcriptome. [ABSTRACT FROM AUTHOR]

Natural rubber of the Para rubber tree (Hevea brasiliensis) is synthesized as a result of prenyltransferase activity. The proteins HRT1, HRT2, and HRBP have been identified as candidate components of the rubber biosynthetic machinery. To clarify the contribution of these proteins to prenyltransferase activity, we established a cell-free translation system for nanodisc-based protein reconstitution and measured the enzyme activity of the protein-nanodisc complexes. Co-expression of HRT1 and HRBP in the presence of nanodiscs yielded marked polyisoprene synthesis activity. By contrast, neither HRT1, HRT2, or HRBP alone nor a complex of HRT2 and HRBP manifested such activity. Similar analysis of guayule (Parthenium argentatum) proteins revealed that three HRT1 homologs (PaCPT1–3) manifested prenyltransferase activity only when co-expressed with PaCBP, the homolog of HRBP. Our results thus indicate that two heterologous subunits form the core prenyltransferase of the rubber biosynthetic machinery. A recently developed structure modeling program predicted the structure of such heterodimer complexes including HRT1/HRBP and PaCPT2/PaCBP. HRT and PaCPT proteins were also found to possess affinity for a lipid membrane in the absence of HRBP or PaCBP, and structure modeling implicated an amphipathic α-helical domain of HRT1 and PaCPT2 in membrane binding of these proteins. [ABSTRACT FROM AUTHOR]

Three‐dimensional (3D) printing is a rapidly growing technology and plays an emerging role in several biomedical applications. Polylactic acid (PLA) is one of the most common materials in 3D printing, however, it is chemically inert due to the absence of reactive side chain groups. In this context, in this work, the PLA scaffolds with two different geometries were produced and coated with natural rubber latex (NRL) extracted from the rubber tree Hevea brasiliensis. NRL presents bioactive substances that are related to its biological properties. The results revealed scaffolds with interconnected pores and pores sizes from 600 to 1300 μm. The NRL coatings caused a decrease in pore size. Infrared spectra showed that 2 NRL layers were more efficient in coverage. Compressive strength values obtained are in agreement with the spongy bones value (22–24 MPa for crossbar and 20–22 MPa for roundbar cube). Finally, the hemolytic activity of the PLA scaffold was 3%, while the scaffolds coated with 1 and 2 NRL layers presented values of 0%, indicating a potential use in biomedical applications due to the absence of hemolytic effects. [ABSTRACT FROM AUTHOR]

The expansion of rubber (Hevea brasiliensis) cultivation plantation over the past few decades has been significantly explosive in Xishuangbanna, southwest China. More and more evidences concerning the expansion of rubber plantations lead to the negative influence to local regional hydrology. It is vital to explore the impact of climate change and rubber (Hevea brasiliensis) plantation expansion on reference evapotranspiration (ET0) for the sustainable and efficient use of regional water resources. In this study, the spatiotemporal variation of ET0 as well as its relationship in rubber plantations area in Xishuangbanna from 1970–2017 were analyzed by using trend, correlation and contribution analysis. The results showed that the rubber plantation was 12,768 ha yr–1 from 1990 to 2017 in Xishuangbanna, and nearly 40.8% of new rubber plantations expanded above 900 m in altitude from 2000 to 2017. Sunshine duration and average relative humidity were the key meteorological factors that affect ET0 in Xishuangbanna, with the sensitivity coefficient of 0.51 and 0.35, respectively. The multiyear relative change of ET0 in Xishuangbanna was 9.18%, and the total contribution of major climate factors was 7.87% during 1970 and 2017. The average relative humidity in the plantation area decreases, which directly leads to the increase of ET0. The amount of ET0 change from 2000 to 2017 affected by climate change increased at 3.13 mm/10a, whereas it was 2.17 mm/10a affected by the expansion of rubber plantations by quantitative separation. ET0 was significantly affected by climate change but intensified by the expansion of rubber plantation. [ABSTRACT FROM AUTHOR]

Here, we report the complete genome sequence and organization of a novel virus detected in rubber trees (Hevea brasiliensis). Because the infected plants were asymptomatic, this virus was tentatively named "rubber tree latent virus 1" (RTLV1). The full genome of RTLV1 is 9,422 nt in length and contains three open reading frames with a 157-nt 5' untranslated region (UTR) and a 316-nt 3' UTR. The replicase shares the highest amino acid (aa) sequence identity (32.62%), with only 31% query coverage, with the replicase of Hubei virga-like virus 11. Phylogenetic analysis based on the aa sequence of ORF1 showed that RTLV1 clustered with unclassified members of the family Virgaviridae in a clade that was not closely related to any genus in this family. [ABSTRACT FROM AUTHOR]

Basal stem rot (BSR), caused by Ganoderma spp., is one of the most important emerging oil palm diseases in Colombia, and is restricted to two oil palm production areas in the country. To identify the causal agent of the disease, basidiocarp of oil palms affected by BSR were used to prepare isolates, and their pathogenicity was then assessed in pre-nursery plants. Four-month-old oil palm seedlings were inoculated with rubber wood (Hevea brasiliensis) blocks colonized with dikaryotic mycelia of Ganoderma. The incidence, severity, and symptoms of the pathogen were assessed. A multiregional analysis (ITS, rpb2, and tef1-α) was carried out to identify the isolates; all isolates were determined to be Ganoderma zonatum. Phylogenetic analyses with the three regions yielded concordant phylogenetic information and supported the distinction of the isolates with high bootstrap support. Seven isolates (CPBsZN-01-29, CPBsZN-02-30, CPBsZN-03-31, CPBsZN-04-34, CPBsZN-05-35, CPBsZN-06-36, and CPBsZN-07-38) were pathogenic in oil palm, with incidences greater than 90% and a maximum severity of 34%, and the highest severity index was found in isolates CPBsZN-03-31, CPBsZN-04-34, and CPBsZN-06-36. The pathogen was recovered from inoculated oil palms in all cases. This study reveals the pathogenic association of Ganoderma zonatum with BSR in Colombia. [ABSTRACT FROM AUTHOR]

Noncoding RNAs (ncRNAs) play pivotal roles in various biological processes in plants. However, the role of ncRNAs in tapping panel dryness (TPD) of rubber tree (Hevea brasiliensis Muell. Arg.) is largely unknown. Here, the whole transcriptome analyses of bark tissues from healthy and TPD trees were performed to identify differentially expressed long ncRNAs (DELs), microRNAs/miRNAs (DEMs), genes (DEGs) and their regulatory networks involved in TPD. A total of 263 DELs, 174 DEMs and 1574 DEGs were identified in the bark of TPD tree compared with that of healthy tree. Kyoto Encyclopedia of Genes and Genomes analysis revealed that most of the DEGs and targets of DELs and DEMs were mainly enriched in metabolic pathways, biosynthesis of secondary metabolites and plant hormone signal transduction. Additionally, the majority of DEGs and DELs related to rubber biosynthesis were downregulated in TPD trees. Furthermore, 98 DEGs and 44 DELs were targeted by 54 DEMs, 190 DEGs were identified as putative targets of 56 DELs, and 2 and 44 DELs were predicted as precursors and endogenous target mimics of 2 and 6 DEMs, respectively. Based on these, the DEL–DEM–DEG regulatory network involved in TPD was constructed, and 13 hub DELs, 3 hub DEMs and 2 hub DEGs were identified. The results provide novel insights into the regulatory roles of ncRNAs underlying TPD and lay a foundation for future functional characterization of long ncRNAs, miRNAs and genes involved in TPD in rubber tree. [ABSTRACT FROM AUTHOR]

P proteins encoded by SEOs (sieve element occlusion) have been shown to be associated with the blockage of sieve tubes after injury in many plants, but the presence of SEO genes and their association with rubber tree laticifer plugging and latex yield remain unclear. Through a systematic identification and analysis, seven SEO genes were identified from the rubber tree genome. The physicochemical properties of their proteins, gene structures, conserved domains, and locations on chromosomes were analyzed. According to their phylogenetic distance, HbSEOs were divided into two clusters. The transcript levels of HbSEO genes varied with tissues, in which HbSEO3 and HbSEO4 were most highly expressed in leaf, bark, and latex. HbSEOs could be induced by ethephon, methyl jasmonate, mechanical injury, and tapping; furthermore, they were highly expressed in trees with short flow duration, suggesting their possible association with rubber tree laticifer plugging and latex yield. To our knowledge, this is the first report of HbSEOs in rubber trees. It provides us with a better understanding of the mechanism of laticifer plugging. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate some of the properties of experimental wood plastic composite (WPC) panels manufactured from a low percentage of rubberwood (Hevea brasiliensis Muell. Arg), waste polyethylene terephthalate (PET) and silica at three different ratios. It was determined that water absorption values of the samples decreased with the increasing amount of PET in the panels. The lowest absorption value of 0.34% was determined for the samples having 40% PET in their content as a result of 24-h soaking. The highest hardness value of 4492 N was found for the samples made with the combination of rubberwood, PET and silica at 10%, 40% and 50%, respectively. The compressive strength of WPC specimens also followed a similar trend with the hardness characteristics of the panel and improved with increasing PET percentage. Statistical analyses revealed that values of compression strength, hardness, 2-h and 24-h water absorption of the specimens made with 20, 30, and 40% PET content resulted in significant difference from each other (p ≤ 0.0001). Based on the findings in this study it appears that increasing silica content in the samples adversely influenced their mechanical properties while creating a certain level of enhancement of water absorption of the specimens. It seems that using a combination of waste PET and a limited amount of silica with a low percentage of wood particles could have the potential to produce value-added environmentally friendly composites to be used for different applications. [ABSTRACT FROM AUTHOR]

Latex flow in Hevea brasiliensis (the Para rubber tree), the sole commercial source of natural rubber (cis -1,4-polyisoprene, NR), renders it uniquely suited for the study of plant stress responses. Calcineurin B-like interacting protein kinases (CIPK) serving as calcium-sensor protein kinases react with calcineurin B-like proteins (CBL) to play crucial roles in hormone signaling transduction and response to abiotic stress in plant developmental processes. However, little is known about their functions in Hevea. In this study, a total of twelve CBL (HbCBL) and thirty CIPK (HbCIPK) genes were identified from the Hevea genome. Structure and phylogenetic analysis assigned these CIPKs to five groups and CBLs to four groups, and mapped onto fourteen of the eighteen Hevea chromosomes. RNA-seq and qPCR analysis showed that the expressions of HbCBL and HbCIPK genes varied in the seven Hevea tissues examined, i.e., latex (cytoplasm of rubber-producing laticifers), bark, leaf, root, seed, female flower, and male flower. The expressions of two HbCBL and sixteen HbCIPK genes showed upward trends during leaf development. Following ethylene yield stimulation and the latex tapping treatment, both practices invoking stress, the expression levels of most latex-expressed genes were significantly altered. Yeast two-hybrid test revealed interactions for multiple combinations of HbCBLs and HbCIPKs with substantial gene expression in latex or other Hevea tissues. However, all the HbCBL-HbCIPK complexes examined did not recruit HbSOS1 or AtSOS1 to form functional salt tolerance SOS pathway in yeast cells. Taken together, the results suggested a role of the Hevea CBL-CIPK network as a point of convergence for several different signaling pathways in growth, development, and stress responses in relation to latex production. [ABSTRACT FROM AUTHOR]

Natural rubber, an important industrial raw material with wide applications, is harvested in the form of latex (cytoplasm of rubber-producing laticifers) from Hevea brasiliensis (para rubber tree) by the way of tapping. Conspicuous stimulation on latex production is observed for the first few tappings conducted on virgin (untapped before) or resting (tapped before but no tapping for a period) rubber trees. To understand the underlying mechanisms, an integrative analysis of the latex transcriptome and proteome was conducted on virgin or resting Hevea trees for the first five tappings. A total of 505 non-redundant differentially expressed (DE) transcript-derived fragments (TDFs) were identified by silver-staining cDNA-AFLP, with 217 exhibiting patterns of upregulated, 180 downregulated and 108 irregularly-regulated. Meanwhile, 117 two dimensional gel electrophoresis DE-protein spots were isolated and subjected to mass spectrometry analysis, with 89 and 57 being successfully identified by MALDI-TOF and MALDI-TOF/TOF, respectively. About 72.5% DE-TDFs and 76.1% DE-proteins were functionally annotated and categorized. Noteworthily, most of the DE-TDFs implicated in sugar transport and metabolism as well as rubber biosynthesis were upregulated by the tapping treatment. The importance of sugar metabolism in harvesting-induced latex production was reinforced by the identification of abundant relevant DE-protein spots. About 83.8% of the randomly selected DE-TDFs were validated for expression patterns by semi-quantitative RT-PCR, and an 89.7% consistency for the 29 latex regeneration-related DE-TDFs examined by quantitative RT-PCR analysis. In brief, our results reveal extensive physiological and molecular changes in Hevea laticifers incurred by the tapping treatment, and the vast number of DE genes and proteins identified here contribute to unraveling the gene regulatory network of tapping-stimulated latex production. [ABSTRACT FROM AUTHOR]

This study aimed to identify rubber clones, suitable for rubber-timber production. An experiment was established in randomized complete block design to evaluate the effects of two different planting densities on girth, girth increment, bark thickness, latex yield per tapping per tree (g/t/t), incident of tapping panel dryness disease, and wood potential of nine rubber clones, including RRIV 2, RRIV 3, RRIV 4, RRIV 5, RRIV 107, PB 235, PB 260, PB 330, and RRIC 121. Data of girth, girth increment, bark thickness were collected in the 7th year, prior to opening for tapping, and 17th year of planting. In contrast, data of latex yield were collected in the 3rd and the 11th tapping year, and wood potential was compared based on the data collected in the 11th tapping year. As a result, there were no significant interactions between clones and planting density in girth growth, latex yield, tapping panel dryness and bark thickness, and the first tapping panel (BO-1). There were no significant interactions between clone and planting density on girth growth, latex yield, tapping panel dryness, and bark thickness when these clones were tapped on the first tapping panel (BO- 1). Meanwhile, there were significant interactions between clones and planting density on girth growth, girth increment, and latex yield when the trees were tapped on the second tapping panel (BO-2). Statistical comparison of mean diameters at breast height and bole volume per tree of the same clones at two different planting densities showed that most of the studied clones gave significant differences. However, no significant differences resulted in the statistical comparison of the mean bole height of the same clones at two different planting densities. The total bole volume per hectare of all studied clones was larger at high planting density than at normal planting density. However, the bole volume per tree at high planting density was smaller than that at normal planting density. Clone RRIC 121 could be considered a suitable clone for latex and timber productions. The favorable planting density for commercial timber production is high. [ABSTRACT FROM AUTHOR]