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Background: Tapping panel dryness (TPD) in rubber tree has become the most severe restricting factor of natural rubber production. To date, there is no effective measures to prevent and control TPD. Previous studies primarily focused on analyzing the molecular mechanism underlying TPD occurrence. However, there is no research on the molecular mechanism of TPD recovery. Results: In this study, the TPD trees were recovered by treatment with TPD rehabilitation nutrient agents that could promote the recovery of latex flow on the tapping panel of TPD trees. The genes and proteins involved in TPD recovery were first identified by employing integrated transcriptomics and proteomics analyses. In total, 2029 differentially expressed genes (DEGs) and 951 differentially expressed proteins (DEPs) were detected in the bark of recovery trees compared to that of TPD trees. Among them, 19 DEPs and 11 DEGs were found to be involved in the starch and sucrose metabolism pathway, suggesting their important roles in regulating the syntheses of sucrose and D-glucose, which were the key precursors of natural rubber biosynthesis. Furthermore, 16 DEPs and 15 DEGs were identified in the rubber biosynthesis pathway. Interestingly, almost all the DEPs and DEGs related to rubber biosynthesis exhibited significantly up-regulated expressions in the recovery trees, indicating that latex biosynthesis were probably markedly enhanced during TPD recovery. Conclusions: These results provide new insights into the molecular mechanisms underlying TPD recovery, as well as excellent supplements to the mechanisms of TPD occurrence, which will contribute to the development of more effective agents for the prevention and treatment of TPD in the future. [ABSTRACT FROM AUTHOR]

ATP synthase is a key enzyme in photophosphorylation in photosynthesis and oxidative phosphorylation in respiration, which can catalyze the synthesis of ATP and supply energy to organisms. ATP synthase has been well studied in many animal species but has been poorly characterized in plants. This research identified forty ATP synthase family members in the rubber tree, and the phylogenetic relationship, gene structure, cis-elements, and expression pattern were analyzed. These results indicated that the ATP synthase of mitochondria was divided into three subgroups and the ATP synthase of chloroplast was divided into two subgroups, respectively. ATP synthase in the same subgroup shared a similar gene structure. Evolutionary relationships were consistent with the introns and exons domains, which were highly conserved patterns. A large number of cis elements related to light, phytohormones and stress resistance were present in the promoters of ATP synthase genes in rubber trees, of which the light signal accounts for the most. Transcriptome and qRT-PCR analysis showed that HbATP synthases responded to cold stress and hormone stimulation, and the response to ethylene was most significant. HbMATPR3 was strongly induced by ethylene and salicylic acid, reaching 122-fold and 17-fold, respectively. HbMATP7-1 was 41 times higher than the control after induction by jasmonic acid. These results laid a foundation for further studies on the function of ATP synthase, especially in plant hormone signaling in rubber trees. [ABSTRACT FROM AUTHOR]

The rubber tree Hevea brasiliensis (Willd. Ex Adr. De Juss.) Müell Arg.] is an important source of latex for the production natural rubber. Natural rubber is an important biopolymer used in various industries, but aspects related to hormonal regulation in biosynthesis are still unknown, which would allow optimizing its production. We review the molecular and physiological mechanisms of increases latex regeneration and flow by the stimulation of rubber trees with exogenous applications of ethylene and jasmonate. We found that the increase in latex regeneration by ethylene is due to the increase in gene level expression and enzymatic activity of key photosynthesis and glycolysis enzymes for the generation of precursors in the first phase of rubber biosynthesis. Latex flow is supported by up-regulated genes in sucrose metabolism such as invertases, induction of sucrose transporters (SUT), and aquaporins (PIP) to maintain flow and turgor pressure in laticifers. Meanwhile, the increase in latex yield mediated by jasmonate may be due to the induction of laticifer differentiation in the long term and in the short term be mediated by the induction of small rubber particles (SRPP) as non-enzymatic cofactors in the production of latex. This information contributes to the knowledge of latex biosynthesis, which allows for a greater support for the exogenous application of jasmonates and ethylene to regulate its production.

Simple Summary: Powdery mildew is a significant disease affecting rubber trees, which reduces yield and quality by forming white fungal patches on leaves. Although in recent years, object detection technologies in agriculture application have improved, many cases especially small-scale regions remain undetected. In this study, we proposed PM-YOLO, an advanced detection model for automatically grading rubber tree powdery mildew. The proposed model integrates innovative modules to achieve superior performance, (1) Feature Focus and Diffusion Mechanism (FFDM) enhances multi-scale feature integration, and (2) Dimension-Aware Selective Integration (DASI) module optimizes the detection of small targets. Additionally, we developed an automatic grading algorithm to quantify disease severity using a precise, formula-driven approach based on leaf damage. Furthermore, we constructed a powdery mildew datasets containing 6200 images with 38,000 annotations for powdery mildew detection task. Experimental results demonstrated that PM-YOLO outperformed the state-of-the-art methods in precision and recall. This work offers an approach for early detection and management of powdery mildew, thereby promoting sustainable rubber tree cultivation. Powdery mildew has become a significant disease affecting the yield and quality of rubber trees in recent years. It typically manifests on the leaf surface at an early stage, rapidly infecting and spreading throughout the leaves. Therefore, early detection and intervention are essential to reduce the resulting losses due to this disease. However, the conventional methods of disease detection are both time-consuming and labor-intensive. In this study, we proposed a novel deep-learning-based approach for detecting powdery mildew in rubber trees, even in complex backgrounds. First, to address the lack of existing datasets on rubber tree powdery mildew, we constructed a dataset comprising 6200 images and 38,000 annotations. Second, based on the YOLO framework, we integrated a multi-scale fusion module that combines a Feature Focus and Diffusion Mechanism (FFDM) into the neck of the detection architecture. We designed an overall focus diffusion architecture and introduced a Dimension-Aware Selective Integration (DASI) module to enhance the detection of small powdery mildew targets, naming the model PM-YOLO. Furthermore, we proposed an automatic grading detection algorithm to evaluate the severity of powdery mildew on rubber tree leaves. The experimental results demonstrated that the proposed method achieved 86.9% mean average precision (mAP) and 85.6% recall, which outperformed the standard YOLOv10 by 7.6% mAP and 8.2% recall. This approach offered accurate and real-time detection of powdery mildew rubber trees, providing an effective solution for early diagnosis through automated grading. [ABSTRACT FROM AUTHOR]

Efficient and non-destructive detection of rubber tree diseases is of great significance for optimizing disease control measures for pesticide application and fertilization. In this study, the feasibility of rubber yellow-leaf disease monitoring based on a low-altitude unmanned aerial vehicle (UAV) remote sensing platform was explored, and a low-cost method for detecting yellow-leaf disease based on visible light sensors was proposed. We compared the difference between the spectral response of each band of the visible light sensor in the diseased area and the healthy area, and then decorrelated and stretched the image in the RGB color space, thereby enhancing the color separation between highly correlated channels and enhancing the color difference of the image. Then we converted the image to the HSV color space, comparing the detection effect of different morphological parameters on yellow-leaf diseases and optimizing the extraction of the diseased area. The experimental results showed that this study provides the distribution information of yellow-leaf disease of rubber trees, and the R2 of the regression model of rubber trees was greater than 0.8. This study holds significance for optimizing disease control and sustainable development of the rubber industry. [ABSTRACT FROM AUTHOR]

The objective of this paper was to investigate the socio-economic impact of rubber business on latex tappers in Ijebu Waterside Local Government Area of Ogun State, Nigeria using appropriate standard methods The result showed that all the tappers are male, (35.0%) of the respondents are in their 40s, 55.0% are married and 66.0% had secondary school education. Furthermore, all (100.0%) the tappers went through training for a minimum of three months before starting the business and they all admitted that rubber tree lasts for 30yrs and that the shelf life of rubber product is one year. Most (67.0%) claimed that rubber tapping business was moderately profitable and that it has helped improve their standard of living. 92.0% claimed that the cost of maintaining the business was moderate and that the business has a significant impact on the community because it serves as a source of employment to residents and helped to alleviate poverty in the study area. Among the challenges experienced by rubber tappers, insecurity and theft of rubber product stood out as a principal challenge. The study therefore recommends that adequate security should be provided either by the associations they form or by government in order to maximize their profit from the business. [ABSTRACT FROM AUTHOR]

The rubber tree Hevea brasiliensis (Willd. Ex Adr. De Juss.) Müell Arg.] is an important source of latex for the production natural rubber. Natural rubber is an important biopolymer used in various industries, but aspects related to hormonal regulation in biosynthesis are still unknown, which would allow optimizing its production. We review the molecular and physiological mechanisms of increases latex regeneration and flow by the stimulation of rubber trees with exogenous applications of ethylene and jasmonate. We found that the increase in latex regeneration by ethylene is due to the increase in gene level expression and enzymatic activity of key photosynthesis and glycolysis enzymes for the generation of precursors in the first phase of rubber biosynthesis. Latex flow is supported by up-regulated genes in sucrose metabolism such as invertases, induction of sucrose transporters (SUT), and aquaporins (PIP) to maintain flow and turgor pressure in laticifers. Meanwhile, the increase in latex yield mediated by jasmonate may be due to the induction of laticifer differentiation in the long term and in the short term be mediated by the induction of small rubber particles (SRPP) as non-enzymatic cofactors in the production of latex. This information contributes to the knowledge of latex biosynthesis, which allows for a greater support for the exogenous application of jasmonates and ethylene to regulate its production. [ABSTRACT FROM AUTHOR]

Hevea brasiliensis is an evergreen woody tree widely used in industrial production in tropical rain forest. However, rubber trees are extremely vulnerable to low temperature stress, which seriously limits the cultivation and use of rubber trees in low temperature areas. NAC transcription factor gene family is common to many plant species, and can participate in a variety of behaviors that are crucial for plants to cope with the challenges from the environment. However, little is known about the evolution history, function and expression patterns of NAC family in rubber trees. Here, 51 HbNAC genes were identified in rubber tree by genome search, and they were divided into 11 subclasses according to phylogenetic relationship. The members of a subfamily share a similar number of introns and exons. We conducted transcriptome analyses to obtain cold-responsive HbNACs, and the transcriptome data showed the expression of HbNAC26 and HbNAC11 was significantly induced by cold stress, suggesting a potential role of these genes in cold stress. The expression pattern of HbNACs in different tissues and different developmental stages was studied by real-time PCR. In addition, the complementary effect of defective yeast mutants indicated that the HbNAC11 gene could be a positive regulator of cold stress in rubber trees. The results of this study can lay a foundation for studying the biological function of NAC and improving cold resistance breeding of rubber trees. [ABSTRACT FROM AUTHOR]

The basic helix-loop-helix (bHLH) transcription factors play crucial roles in plant growth, development, and stress responses. However, their identification and insights into the understanding of their role in rubber trees remain largely uncovered. In this study, the bHLH gene family was explored and characterized in rubber trees using systematic bioinformatics approaches. In total, 180 bHLH genes were identified in the rubber tree genome, distributed unevenly across 18 chromosomes, and phylogenetic analysis classified these genes into 23 distinct subfamilies. Promoter regions revealed a high density of cis-elements responsive to light and hormones. Enrichment analysis indicated involvement in numerous biological processes, including growth, development, hormone responses, abiotic stress resistance, and secondary metabolite biosynthesis. Protein interaction network analysis identified extensive interactions between HbbHLH genes and other functional genes, forming key clusters related to iron homeostasis, plant growth, and stomatal development. Expression profiling of HbbHLH genes have demonstrated varied responses to endogenous and environmental changes. RT-qPCR of eleven HbbHLH genes in different tissues and under ethylene, jasmonic acid, and cold treatments revealed tissue-specific expression patterns and significant responses to these stimuli, highlighting the roles of these genes in hormone and cold stress responses. These findings establish a framework for exploring the molecular functions of bHLH transcription factors in rubber trees. [ABSTRACT FROM AUTHOR]

The partial substitution of chemical fertilizer with organic fertilizer is a crucial practice for enhancing crop production and quality, although its impact on natural rubber has rarely been explored. In this study, a two-year field experiment was conducted to investigate the impact of different nitrogen application rates and varying proportions of organic nitrogen substitution on dry rubber yield, nitrogen nutrition, and natural rubber properties. Regarding nitrogen application, the control treatment received no nitrogen amendment, while the low-nitrogen treatment was amended with 138 g·tree−1·year−1 of nitrogen. The medium-nitrogen treatment received 276 g·tree−1·year−1 of nitrogen, and the high-nitrogen treatment received 552 g·tree−1·year−1 of nitrogen. In addition, the low-organic-nitrogen substitution treatment and medium-organic-nitrogen substitution treatment were amended with 276 g·tree−1·year−1 of nitrogen each. The results demonstrated that the 50% organic nitrogen substitution treatment resulted in the highest dry rubber yield across all sampling periods, ranging from 46.43 to 94.65 g·tree−1. Additionally, this treatment exhibited superior soil total nitrogen (1067.69 mg·kg−1), available nitrogen (84.06 mg·kg−1), and nitrogen content in roots (1.08%), leaves (3.25%), fresh rubber latex (0.27%), and raw natural rubber (0.44%) compared with other treatments. In terms of the physical properties of natural rubber, the 50% organic nitrogen substitution treatment resulted in advantages in the weight-average molecular weight (1.57 × 106 g·mol−1), number-average molecular weight (0.36 × 106 g·mol−1), plasticity retention index (97.35%), Wallace plasticity (40.25), and Mooney viscosity (81.40). For mechanical properties, natural rubber from the substitution treatment exhibited higher tensile strength (19.84 MPa), greater elongation at break (834.75%), and increased tear strength (31.07 N·mm−1). Overall, the substitution of 50% chemical nitrogen fertilizer with organic nitrogen fertilizer improved nitrogen nutrition in rubber trees by introducing organic nitrogen input, resulting in remarkable enhancements in natural rubber properties. Therefore, the incorporation of organic fertilizer as a substitution for 50% of chemical fertilizer is demonstrated as an effective strategy for improving both the yield and properties of natural rubber. [ABSTRACT FROM AUTHOR]

Powdery mildew and anthracnose are the main diseases of rubber trees. In recent years, there have been large outbreaks in the rubber-planting areas of Asia, seriously affecting the yield and quality of rubber latex. ZAR1 is a conserved and distinctive coiled-coil nucleotide-binding leucine-rich (CNL) repeat in the plant kingdom, playing a crucial role in disease-resistance processes. To elucidate the function of the HbZAR1 gene in rubber trees (Hevea brasiliensis), three candidate HbZAR1 genes were identified using bioinformatics methods and comprehensively analyzed. The results indicate that the HbZAR1 protein is conserved in different plant species. Examination of cis-regulatory element sequences of HbZAR1genes reveals that the HbZAR1 gene promoter exhibits a remarkable enrichment of stress, light, and hormone elements. An expression analysis shows that the expression levels of the three HbZAR1 genes are highest in the bark and lowest in latex. Three HbZAR1 genes can respond to both rubber tree Erysiphe quercicola and Colletotrichum siamense infection; especially, HbZAR1.1 and HbZAR1.2 show significant upregulation in expression levels during the early stages of infection. These findings suggest that the three HbZAR1 genes may be involved in rubber tree susceptibility to E. quercicola and C. siamense through different immune mechanisms. Subcellular localization results indicate that the HbZAR1 genes are expressed in the nucleus and plasma membrane. This study also shows that the three HbZAR1 genes and activated mutant HbZAR1.1D481V do not induce stable ROS production and cell death, suggesting possible gene degradation, functional redundancy, or acting as minor genes in disease resistance. This research provides valuable insights for further studying the function of HbZAR1 genes in rubber trees and the mechanisms of immune molecules. [ABSTRACT FROM AUTHOR]

Rigidoporus microporus, the causative agent of the white root rot disease of rubber trees, poses a significant threat to natural rubber production worldwide. Understanding the molecular mechanisms facilitating its pathogenicity would be crucial for developing effective disease management strategies. The pathogen secretes effector proteins, which play pivotal roles in modulating host immune responses and infection. In this study, in silico analyses identified 357 putative secreted effector proteins from the R. microporus genome. These were then integrated into previous RNA-seq data obtained in response to rubber tree latex exposure. Annotation of putative effectors suggested the abundance of proteins in several families associated with the virulence of R. microporus, especially hydrophobin proteins and glycoside hydrolase (GH) proteins. The contribution of secreted effectors to fungal pathogenicity was discussed, particularly in response to rubber tree latex exposure. Some unknown highly expressed effectors were predicted for the protein structures, revealing their similarity to aminopeptidase, ubiquitin ligase, spherulin, and thaumatin protein. This integrative study further elucidates the molecular mechanism of R. microporus pathogenesis and offers alternative targets for developing control strategies for managing white root rot disease in rubber plantations. [ABSTRACT FROM AUTHOR]

Natural rubber produced by the rubber tree is a vital industrial raw material globally. Seven SCAMP gene family members were identified in the rubber tree, and the phylogenetic tree classified HbSCAMPs into three subfamilies. Significant differences were observed among HbSCAMPs in terms of gene length, number of exons, and composition of conserved motifs. The expansion of HbSCAMPs in the rubber tree genome is associated with segmental duplications. The high expression of HbSCAMP1–6 in petioles and HbSCAMP7 in stem tips, along with their distinct responses to drought, salt, and wound stresses, indicates their crucial roles in substance transport and stress adaptation. Transgenic poplar experiments demonstrated that overexpression of HbSCAMP3 significantly promotes plant height growth, with localization in the tobacco plasma membrane, suggesting its involvement in regulating plant growth through membrane transport processes. These findings enhance the understanding of HbSCAMPs in rubber trees and provide new insights into how plants finely tune gene family members to adapt to environmental changes. [ABSTRACT FROM AUTHOR]

BACKGROUND: In order to address the issues of uneven pesticide deposition and low pesticide utilization in rubber gardens caused by the traditional diffuse plant protection spraying method, this study focuses on the air‐assisted powder sprayer and proposes a variable pesticide application control system. A variable pesticide application decision‐making model integrating the leaf area index (LAI) was designed based on powdery mildew control standards and individual rubber tree information. According to the target powder spraying accuracy requirements, a control model of the air velocity adjustment device was established and a fuzzy proportional‐integral‐differential (PID) air velocity control system was developed. RESULTS: The simulation results indicate that the wind speed control system exhibits a maximum overshoot of 2.18% and an average response time of 1.48 s. The field experiment conducted in a rubber plantation revealed that when the air‐assisted powder sprayer operates in the variable powder spraying mode, the average response time of the control system is 2.5 s. The control accuracy of each executive mechanism exceeded 95.9%. The deposition coefficient of variation (CV) at different canopy heights was relatively consistent, with values of 35.38%, 36.26% and 36.90%. In comparison to the quantitative mode, the variable mode showed a significant 20.03% increase in the effective utilization rate of sulfur powder. CONCLUSION: These research findings provide valuable technical support for the advancement of mechanized variable powder spraying equipment in rubber tree cultivation. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

ABSTRACT Plant-associated microbial communities strongly relate to host health and productivity. Still, our knowledge of microbial community spatiotemporal patterns in soil–plant continuum is largely limited. Here, we explored the spatiotemporal dynamics of fungal communities across multiple compartments (phyllosphere, leaf endosphere, soil, rhizosphere, rhizoplane, and root endosphere) of rubber tree in two contrasting seasons collected from Hainan Island and Xishuangbanna. Our results demonstrate that the fungal alpha and beta diversity exhibited distinct pattern; the alpha diversity is highly dependent on seasonal changes, while beta diversity only showed a geographical variation pattern. The season-specific environmental factors (e.g., climatic factors) were the most important factors in shaping fungal alpha diversity across the soil–plant continuum. Physicochemical properties explained some of the microbial beta diversity spatiotemporal variation observed, with leaf phosphorus (P) and soil available potassium (AK) likely being the main factors that drove the geographical variation. We further identified the variation of edaphic (e.g., AK) and leaf physicochemical factors (e.g., P) were mainly caused by regional sites (P < 0.05). Taken together, our study provides an empirical evidence that the distinct spatiotemporal patterns of alpha and beta diversity of rubber tree fungal diversity and significantly expand our understanding of ecological drivers of plant-associated microbial communities.IMPORTANCEPlants harbor diverse microorganisms in both belowground and aboveground compartments, which play a vital role in plant nitrogen supply and growth promotion. Understanding the spatiotemporal patterns of microbial communities is a prerequisite for harnessing them to promote plant growth. In this study, we show that the alpha and beta diversity of soil–plant continuum in rubber tree exhibited distinct spatiotemporal pattern. Alpha diversity is highly dependent on seasonal changes, while beta diversity only showed a geographical variation pattern. Climatic factors were the most important factors in shaping fungal alpha diversity. Leaf phosphorus (P) and soil available potassium (AK) were major drivers to induce geographical variation.

Natural rubber is a vital material for the industry, which is usually obtained from the rubber tree (Hevea brasiliensis). Considering that it is not possible to grow this tree in many areas, it seems necessary to find an alternative source for this valuable material. In this study, the presence of natural rubber in the Ghandaroun plant with the scientific name Chondrilla juncea was investigated from a molecular and biochemical point of view. The results showed that a significant amount of natural rubber can be extracted from the roots of this plant in the autumn season by using the enzyme method. Also, in the present study, the key gene of cis-prenyl transferase (CPT) involved in the biosynthesis of natural rubber was identified and sequenced using different primers on the genomic DNA of this plant. After assembling the sequences obtained, the complete sequence of this gene was obtained. Comparing the nucleotide and protein sequences of this gene showed a great similarity to the CPT gene in other plants of this family and even the rubber tree. This article represents the first report of natural rubber production in Ghandaroun plant. Further investigations and breeding programs, it may position this plant as a novel commercial source for natural rubber production. [ABSTRACT FROM AUTHOR]

Purpose: Herein, the extraction of lignin from rubber tree residues (Hevea brasiliensis Müll. Arg), particularly from the seed shell, is reported with the aim of providing added value to this plantation. Methods: The protocol employed consisted of an organosolv extraction using formic or acetic acids and p-TsOH as catalyst assisted by ultrasound, avoiding the use of high temperatures and mineral acids. Results: 22% yield of lignin was obtained from the dried rubber seed shell using the formic acid/p-TsOH combination in comparison with 13% yield obtained with acetic acid/p-TsOH. The extracted lignin was oxidized isolating typical fragments derived from syringyl, guaiacyl and p-hydroxyphenyl units. The lignin was characterized by IR, UV, NMR, TGA and DSC. Moreover, total phenol content and antioxidant activity were also evaluated. Conclusion: The results exhibited the presence of typical lignin aromatic composition. The lignin obtained by the seed shell could be effectively employed in numerous future applications and the method could be considered as a low-cost acid catalysed process. [ABSTRACT FROM AUTHOR]

The precise acquisition of phenotypic parameters for individual trees in plantation forests is important for forest management and resource exploration. The use of Light-Detection and Ranging (LiDAR) technology mounted on Unmanned Aerial Vehicles (UAVs) has become a critical method for forest resource monitoring. Achieving the accurate segmentation of individual tree crowns (ITCs) from UAV LiDAR data remains a significant technical challenge, especially in broad-leaved plantations such as rubber plantations. In this study, we designed an individual tree segmentation framework applicable to dense rubber plantations with complex canopy structures. First, the feature extraction module of PointNet++ was enhanced to precisely extract understory branches. Then, a graph-based segmentation algorithm focusing on the extracted branch and trunk points was designed to segment the point cloud of the rubber plantation. During the segmentation process, a directed acyclic graph is constructed using components generated through grey image clustering in the forest. The edge weights in this graph are determined according to scores calculated using the topologies and heights of the components. Subsequently, ITC segmentation is performed by trimming the edges of the graph to obtain multiple subgraphs representing individual trees. Four different plots were selected to validate the effectiveness of our method, and the widths obtained from our segmented ITCs were compared with the field measurement. As results, the improved PointNet++ achieved an average recall of 94.6% for tree trunk detection, along with an average precision of 96.2%. The accuracy of tree-crown segmentation in the four plots achieved maximal and minimal R2 values of 98.2% and 92.5%, respectively. Further comparative analysis revealed that our method outperforms traditional methods in terms of segmentation accuracy, even in rubber plantations characterized by dense canopies with indistinct boundaries. Thus, our algorithm exhibits great potential for the accurate segmentation of rubber trees, facilitating the acquisition of structural information critical to rubber plantation management. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate the development of Davidiella sp. and its asexual form, Cladosporium sp., under different environmental conditions in the rubber tree (Hevea brasiliensis). Rubber tree leaves were inoculated with a spore suspension and kept in a humid chamber under different temperatures and wetness periods. The behavior of the fungi was evaluated using a scanning electron microscope (SEM) and an ultraviolet light microscope (UV). In the images obtained in SEM, four hours after inoculation of the fungus, it was possible to verify the germination and penetration of conidia at temperatures of 10 to 20 °C. The formation of conidiophores was verified from six hours after inoculation, indicating that it is in the reproductive period. In the sexual phase, in SEM, from four hours after inoculation, it was possible to verify the formation of small protuberances at temperatures between 10 and 20 °C. These black dots evolve into circular, protruding black spots, like the symptoms of black crust, with apparent spore formation on them. The data obtained from the UV analyses corroborate those from SEM, showing that the fungus has good development in its two phases between temperatures of 20 and 25 °C and that the period of wetness on the leaf can contribute to the initial development of the pathogen. [ABSTRACT FROM AUTHOR]

The objective of this paper was to investigate the socio-economic impact of rubber business on latex tappers in Ijebu Waterside Local Government Area of Ogun State, Nigeria using appropriate standard methods The result showed that all the tappers are male, (35.0%) of the respondents are in their 40s, 55.0% are married and 66.0% had secondary school education. Furthermore, all (100.0%) the tappers went through training for a minimum of three months before starting the business and they all admitted that rubber tree lasts for 30yrs and that the shelf life of rubber product is one year. Most (67.0%) claimed that rubber tapping business was moderately profitable and that it has helped improve their standard of living. 92.0% claimed that the cost of maintaining the business was moderate and that the business has a significant impact on the community because it serves as a source of employment to residents and helped to alleviate poverty in the study area. Among the challenges experienced by rubber tappers, insecurity and theft of rubber product stood out as a principal challenge. The study therefore recommends that adequate security should be provided either by the associations they form or by government in order to maximize their profit from the business.

Hevea brasiliensis is a forest species with potential for commercial planting for both latex and timber production at the end of the latex production cycle. This study aimed to determine the genetic variability of growth traits and wood properties in a 33-year-old clonal plantation of H. brasiliensis in the region of Selvíria, state of Mato Grosso do Sul. Significant differences were detected among the clones for DBH and total tree height. For the physical properties of the wood, only volumetric shrinkage showed a significant difference between clones; however, for all anatomical dimensions and mechanical properties, significant differences were found. Clone IAN717 stood out for the highest growth, while RRIM600 had the lowest growth. In terms of wood properties, clone RRIM600 exhibited highest mechanical resistance, while GT1 showed the lowest resistance. Most wood properties varied in the pith-to-bark direction, with the lowest values found in the pith region and the highest in the bark region, except for vessel frequency, where the opposite trend occurred. The highest heritability coefficients were observed for DBH, volumetric shrinkage in the bark region, vessel element diameter in the intermediate region, and vessel frequency in the bark region. The genetic correlation coefficient was high, positive, and significant between traits such as shear strength x modulus of rupture, modulus of elasticity x modulus of rupture, and volumetric shrinkage x modulus of rupture, indicating that selection for one trait may result in indirect gains in another.

ATP synthase is a key enzyme in photophosphorylation in photosynthesis and oxidative phosphorylation in respiration, which can catalyze the synthesis of ATP and supply energy to organisms. ATP synthase has been well studied in many animal species but has been poorly characterized in plants. This research identified forty ATP synthase family members in the rubber tree, and the phylogenetic relationship, gene structure, cis-elements, and expression pattern were analyzed. These results indicated that the ATP synthase of mitochondria was divided into three subgroups and the ATP synthase of chloroplast was divided into two subgroups, respectively. ATP synthase in the same subgroup shared a similar gene structure. Evolutionary relationships were consistent with the introns and exons domains, which were highly conserved patterns. A large number of cis elements related to light, phytohormones and stress resistance were present in the promoters of ATP synthase genes in rubber trees, of which the light signal accounts for the most. Transcriptome and qRT-PCR analysis showed that HbATP synthases responded to cold stress and hormone stimulation, and the response to ethylene was most significant. HbMATPR3 was strongly induced by ethylene and salicylic acid, reaching 122-fold and 17-fold, respectively. HbMATP7-1 was 41 times higher than the control after induction by jasmonic acid. These results laid a foundation for further studies on the function of ATP synthase, especially in plant hormone signaling in rubber trees.

The majority of the world's natural rubber comes from the rubber tree (Hevea brasiliensis). As a key enzyme for synthesizing phenylpropanoid compounds, phenylalanine ammonia-lyase (PAL) has a critical role in plant satisfactory growth and environmental adaptation. To clarify the characteristics of rubber tree PAL family genes, a genome-wide characterization of rubber tree PALs was conducted in this study. Eight PAL genes (HbPAL1-HbPAL8), which spread over chromosomes 3, 7, 8, 10, 12, 13, 14, 16, and 18, were found to be present in the genome of H. brasiliensis. Phylogenetic analysis classified HbPALs into groups I and II, and the group I HbPALs (HbPAL1-HbPAL6) displayed similar conserved motif compositions and gene architectures. Tissue expression patterns of HbPALs quantified by quantitative real-time PCR (qPCR) proved that distinct HbPALs exhibited varying tissue expression patterns. The HbPAL promoters contained a plethora of cis-acting elements that responded to hormones and stress, and the qPCR analysis demonstrated that abiotic stressors like cold, drought, salt, and H2O2-induced oxidative stress, as well as hormones like salicylic acid, abscisic acid, ethylene, and methyl jasmonate, controlled the expression of HbPALs. The majority of HbPALs were also regulated by powdery mildew, anthracnose, and Corynespora leaf fall disease infection. In addition, HbPAL1, HbPAL4, and HbPAL7 were significantly up-regulated in the bark of tapping panel dryness rubber trees relative to that of healthy trees. Our results provide a thorough comprehension of the characteristics of HbPAL genes and set the groundwork for further investigation of the biological functions of HbPALs in rubber trees. [ABSTRACT FROM AUTHOR]

Powdery mildew significantly impacts the yield of natural rubber by being one of the predominant diseases that affect rubber trees. Accurate, non-destructive recognition of powdery mildew in the early stage is essential for the cultivation management of rubber trees. The objective of this study is to establish a technique for the early detection of powdery mildew in rubber trees by combining spectral and physicochemical parameter features. At three field experiment sites and in the laboratory, a spectroradiometer and a hand-held optical leaf-clip meter were utilized, respectively, to measure the hyperspectral reflectance data (350–2500 nm) and physicochemical parameter data of both healthy and early-stage powdery-mildew-infected leaves. Initially, vegetation indices were extracted from hyperspectral reflectance data, and wavelet energy coefficients were obtained through continuous wavelet transform (CWT). Subsequently, significant vegetation indices (VIs) were selected using the ReliefF algorithm, and the optimal wavelengths (OWs) were chosen via competitive adaptive reweighted sampling. Principal component analysis was used for the dimensionality reduction of significant wavelet energy coefficients, resulting in wavelet features (WFs). To evaluate the detection capability of the aforementioned features, the three spectral features extracted above, along with their combinations with physicochemical parameter features (PFs) (VIs + PFs, OWs + PFs, WFs + PFs), were used to construct six classes of features. In turn, these features were input into support vector machine (SVM), random forest (RF), and logistic regression (LR), respectively, to build early detection models for powdery mildew in rubber trees. The results revealed that models based on WFs perform well, markedly outperforming those constructed using VIs and OWs as inputs. Moreover, models incorporating combined features surpass those relying on single features, with an overall accuracy (OA) improvement of over 1.9% and an increase in F1-Score of over 0.012. The model that combines WFs and PFs shows superior performance over all the other models, achieving OAs of 94.3%, 90.6%, and 93.4%, and F1-Scores of 0.952, 0.917, and 0.941 on SVM, RF, and LR, respectively. Compared to using WFs alone, the OAs improved by 1.9%, 2.8%, and 1.9%, and the F1-Scores increased by 0.017, 0.017, and 0.016, respectively. This study showcases the viability of early detection of powdery mildew in rubber trees. [ABSTRACT FROM AUTHOR]

The cultivation of Hevea brasiliensis (rubber) is promoted as a productive and ecological alternative, especially in agroforestry systems, although research is still required to address its impact on soil chemical conditions. This study aimed evaluate the possible effects of five types of land use on the chemical properties of horizons A and B in soils of the Colombian Amazon: agroforestry system of H. brasiliensis with timber and fruit trees, agroforestry system of H. brasiliensis associated with stubble, H. brasiliensis monoculture, secondary forest as positive control and native grass as negative control. The conditions of pH, exchangeable aluminum, organic carbon, potassium, phosphorus, calcium, magnesium, base saturation and cationic exchange capacity were evaluated. Similarities in soil chemical properties were found between secondary forest, agroforestry systems with fruit trees and agroforestry systems associated with stubble. The H. brasiliensis monoculture did not present significant differences with the native pasture. The pH was the only variable affected by soil use, while the percentage of organic carbon and the contents of phosphorus, calcium, magnesium and potassium changed depending on the A and B horizons, demonstrating that the variability of the chemical fertility of the clay soils of the Amazon are more related to the characteristics of their horizons than to the type of land use. [ABSTRACT FROM AUTHOR]

Transgenic technology is a crucial tool for gene functional analysis and targeted genetic modification in the para rubber tree (Hevea brasiliensis). However, low efficiency of plant regeneration via somatic embryogenesis remains a bottleneck of successful genetic transformation in H. brasiliensis. Enhancing expression of GROWTH-REGULATING FACTOR 4 (GRF4)-GRF-INTERACTING FACTOR 1 (GIF1) has been reported to significantly improve shoot and embryo regeneration in multiple crops. Here, we identified endogenous HbGRF4 and HbGIF1 from the rubber clone Reyan7-33-97, the expressions of which dramatically increased along with somatic embryo (SE) production. Intriguingly, overexpression of HbGRF4 or HbGRF4-HbGIF1 markedly enhanced the efficiency of embryogenesis in two H. brasiliensis callus lines with contrasting rates of SE production. Transcriptional profiling revealed that the genes involved in jasmonic acid response were up-regulated, whereas those in ethylene biosynthesis and response as well as the S-adenosylmethionine-dependent methyltransferase activity were down-regulated in HbGRF4- and HbGRF4-HbGIF1-overexpressing H. brasiliensis embryos. These findings open up a new avenue for improving SE production in rubber tree, and help to unravel the underlying mechanisms of HbGRF4-enhanced somatic embryogenesis. [ABSTRACT FROM AUTHOR]

Rubber (Hevea brasiliensis) is a priority tree crop that produces natural rubber (NR), making it an important plantation commodity in the Philippines. However, NR production is confronted with major constraints, including rubber diseases resulting in low latex yield. Twenty-five rubber farms located in five major rubber-producing municipalities (Kidapawan, Antipas, Makilala, Matalam and President Roxas) of Cotabato, Philippines, were surveyed for prevalence of major rubber leaf diseases. Information on farm practices and environmental variables was collected. The majority of rubber farmers were smallholders with hectarage planted ranging between 1 and 15 hectares. The most planted clones are RRIM 600 and PB 260, which are high-yielding yet susceptible to many foliar pathogens. Six leaf diseases, viz. Oidium powdery mildew, Colletotrichum leaf disease, Corynespora leaf fall/spot, Phytophthora leaf blight, bird's eye spot and algal spot, were documented in this study. Powdery mildew was the most prevalent in Cotabato with the highest percentage and severity of infections in all plantations, followed by Colletotrichum leaf disease. Information on disease prevalence in surveyed areas is important for disease management actions. [ABSTRACT FROM AUTHOR]

Natural rubber is an important national strategic and industrial raw material. The leaf anthracnose of rubber trees caused by the Colletotrichum species is one of the important factors restricting the yields of natural rubber. In this study, we isolated and identified strain Bacillus velezensis SF334, which exhibited significant antagonistic activity against both C. australisinense and C. siamense, the dominant species of Colletotrichum causing rubber tree leaf anthracnose in the Hainan province of China, from a pool of 223 bacterial strains. The cell suspensions of SF334 had a significant prevention effect for the leaf anthracnose of rubber trees, with an efficacy of 79.67% against C. siamense and 71.8% against C. australisinense. We demonstrated that SF334 can lead to the lysis of C. australisinense and C. siamense mycelia by causing mycelial expansion, resulting in mycelial rupture and subsequent death. B. velezensis SF334 also harbors some plant probiotic traits, such as secreting siderophore, protease, cellulase, pectinase, and the auxin of indole-3-acetic acid (IAA), and it has broad-spectrum antifungal activity against some important plant pathogenic fungi. The genome combined with comparative genomic analyses indicated that SF334 possesses most genes of the central metabolic and gene clusters of secondary metabolites in B. velezensis strains. To our knowledge, this is the first time a Bacillus velezensis strain has been reported as a promising biocontrol agent against the leaf anthracnose of rubber trees caused by C. siamense and C. australisinense. The results suggest that B. velezensis could be a potential candidate agent for the leaf anthracnose of rubber trees. [ABSTRACT FROM AUTHOR]

Natural rubber produced by the rubber tree is a vital industrial raw material globally. Seven SCAMP gene family members were identified in the rubber tree, and the phylogenetic tree classified HbSCAMPs into three subfamilies. Significant differences were observed among HbSCAMPs in terms of gene length, number of exons, and composition of conserved motifs. The expansion of HbSCAMPs in the rubber tree genome is associated with segmental duplications. The high expression of HbSCAMP1–6 in petioles and HbSCAMP7 in stem tips, along with their distinct responses to drought, salt, and wound stresses, indicates their crucial roles in substance transport and stress adaptation. Transgenic poplar experiments demonstrated that overexpression of HbSCAMP3 significantly promotes plant height growth, with localization in the tobacco plasma membrane, suggesting its involvement in regulating plant growth through membrane transport processes. These findings enhance the understanding of HbSCAMPs in rubber trees and provide new insights into how plants finely tune gene family members to adapt to environmental changes.

The objective of this work was to evaluate the development of Davidiella sp. and its asexual form, Cladosporium sp., under different environmental conditions in the rubber tree (Hevea brasiliensis). Rubber tree leaves were inoculated with a spore suspension and kept in a humid chamber under different temperatures and wetness periods. The behavior of the fungi was evaluated using a scanning electron microscope (SEM) and an ultraviolet light microscope (UV). In the images obtained in SEM, four hours after inoculation of the fungus, it was possible to verify the germination and penetration of conidia at temperatures of 10 to 20 °C. The formation of conidiophores was verified from six hours after inoculation, indicating that it is in the reproductive period. In the sexual phase, in SEM, from four hours after inoculation, it was possible to verify the formation of small protuberances at temperatures between 10 and 20 °C. These black dots evolve into circular, protruding black spots, like the symptoms of black crust, with apparent spore formation on them. The data obtained from the UV analyses corroborate those from SEM, showing that the fungus has good development in its two phases between temperatures of 20 and 25 °C and that the period of wetness on the leaf can contribute to the initial development of the pathogen.

Plant PP2C genes are crucial for various biological processes. To elucidate the potential functions of these genes in rubber tree (Hevea brasiliensis), we conducted a comprehensive analysis of these genes using bioinformatics methods. The 60 members of the PP2C family in rubber tree were identified and categorized into 13 subfamilies. The PP2C proteins were conserved across different plant species. The results revealed that the HbPP2C genes contained multiple elements responsive to phytohormones and stresses in their promoters, suggesting their involvement in these pathways. Expression analysis indicated that 40 HbPP2C genes exhibited the highest expression levels in branches and the lowest expression in latex. Additionally, the expression of A subfamily members significantly increased in response to abscisic acid, drought, and glyphosate treatments, whereas the expression of A, B, D, and F1 subfamily members notably increased under temperature stress conditions. Furthermore, the expression of A and F1 subfamily members was significantly upregulated upon powdery mildew infection, with the expression of the HbPP2C6 gene displaying a remarkable 33-fold increase. These findings suggest that different HbPP2C subgroups may have distinct roles in the regulation of phytohormones and the response to abiotic and biotic stresses in rubber tree. This study provides a valuable reference for further investigations into the functions of the HbPP2C gene family in rubber tree. [ABSTRACT FROM AUTHOR]

The stem CO2 efflux (Es) plays an important role in the carbon balance in forest ecosystems. However, a majority of studies focus on ecosystem flux, and little is known about the contribution of stem respiration to ecosystem respiration (Reco) for rubber (Hevea brasiliensis) plantations. We used a portable CO2 analyzer to monitor the rate of Es in situ at different heights (1.5 m, 3.0 m and 4.5 m) in an even-aged rubber plantation from 2019 to 2020. Our results showed that Es exhibited a significant seasonal difference with a minimum value in April and a maximum in September. The mean annual rate of Es at 3.0 m in height (1.65 ± 0.52 μmol·m−2·s−1) was slightly higher than Es at 4.5 m in height (1.56 ± 0.59 μmol·m−2·s−1) and Es at 1.5 m in height (1.51 ± 0.48 μmol·m−2·s−1). No obvious differences in vertical variations were found. An area-based method (Ea) and a volume-based method (Ev) were used to estimate stem respiration at stand levels. One-way ANOVA showed that Ea had no obvious differences in vertical variation (p = 0.62), and Ev indicated differences in vertical variation (p < 0.05). Therefore, the Ea chamber-based measurements at breast height were reasonable and practical extrapolation proxies of stem respiration in an even-aged rubber plantation. With the use of the area-based method, the stem carbon values released from a mature rubber forest were estimated to be 1.214 t C·hm−2·a−1 in 2019 and 1.414 t C·hm−2·a−1 in 2020. Ea/Reco and Ev/Reco showed seasonal changes, with a minimum value in April and a maximum value in December. The leaf area index (LAI) and soil volumetric moisture content (VWC) were the major impact factors of Ea/Reco in an even-aged pure rubber plantation. [ABSTRACT FROM AUTHOR]

In the last 2 years, rubber tree abnormal leaf fall occurred over large area in Xishuangbanna rubber plantation, and the symptoms were similar to those of rubber tree Phytophthora leaf fall disease. In order to clarify the pathogenic species and screen fungicides for effective control of this disease, the pathogen was isolated and purified by tissue isolation and mycelia cusp purification method, and the pathogenicity was determined by Koch' s postulates test, morphological and physiological characteristics, rDNA-ITS and COX II gene sequence analysis. The results showed that the pathogen caused rubber tree abnormal leaf fall was identified as Phytophthora botryosa, which was a new record pathogen of rubber tree Phytophthora leaf fall disease in China. The antibiotic activities of 15 fungicides was tested in vitro with mycelial growth rate method. 48% dimethomorph-cyazofamid SC (suspension concentrate), 80% dimethomorph WG (water dispersible granule), 30% metalaxyl-dimethomorph WG, 35% dimethomorph-cymoxanil SC, 30% floridomide-metalaxyl WG and 0.3% tetramycin AS (aqueoces solution) could effectively inhibit the mycelial growth of the pathogen, with EC50 of 0.137 1, 0.175 9, 0.201 7, 0.2577, 0.265 1, 0.351 0 mg⋅L-1, respectively, which could be used as candidates for control of the disease in the field. [ABSTRACT FROM AUTHOR]

We investigate and characterize the morphophysiological changes related to germination and the initial growth and development of seedlings of wild and cultivated genotypes of the genus Hevea spp. in finding to add value to new clones. Seeds from six genotypes (H. brasiliensis (Willd. Ex A. Juss) Müll. Arg, H. guianensis Aubl., H. spruceana (Benth.) Müll. Arg., RRIM 600, Fx 3844, and IAN 873) were sterilized, and their imbibition curve, germination parameters, and initial seedling growth were characterized. In parallel, the morphology of the germination and post-germination stages was monitored from seeds germinated in washed sand. Morphological differences in the seeds/embryos, different strategies in the imbibition process, emergence, and initial seedling growth were observed. The species H. guianensis and H. spruceana showed the greatest differences in size, shape, and color of the seeds/embryos and initial seedling growth. The characteristics of the seed coat patterns, the seedling imbibition, growth, and development processes can serve as morphophysiological markers for genotype identification and selection. This is the first morphophysiological study of seeds and seedlings of wild and cultivated genotypes of species of the genus Hevea. We conclude that there is considerable phenotypic variability among species of the Hevea genus regarding seed and seedling morphophysiology, which can be explored in the rubber tree breeding programs. [ABSTRACT FROM AUTHOR]

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Based on the meteorological observations since 1981, the impact of climate change on rubber tree planting in Yunnan is analyzed from the aspect of the climatic suitability of rubber tree. The results show that annual average temperature of the main rubber producing counties in the south and east increases by 0.6-0.8℃ in most areas, and more than 1.0℃ in most areas in the west. In January, the average temperature in most areas of the main rubber producing counties in the east of the Ailao Mountain increases by 0-1.0℃, while that in the west increases by 1.0-2.0℃ in the 2010s compared with the 1980s. At the same time, the most suitable and suitable climate area for rubber tree planting increase by 55.3% and 18.6%, respectively. The increased areas are mainly distributed in the west of the Ailao Mountain, indicating that the west area of the Ailao Mountain is more suitable for rubber tree planting due to climate change.

Abstract Background White root rot disease in rubber trees, caused by the pathogenic fungi Rigidoporus microporus, is currently considered a major problem in rubber tree plantations worldwide. Only a few reports have mentioned the response of rubber trees occurring at the non-infection sites, which is crucial for the disease understanding and protecting the yield losses. Results Through a comparative proteomic study using the two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) technique, the present study reveals some distal-responsive proteins in rubber tree leaves during the plant-fungal pathogen interaction. From a total of 12 selected differentially expressed protein spots, several defense-related proteins such as molecular chaperones and ROS-detoxifying enzymes were identified. The expression of 6 candidate proteins was investigated at the transcript level by Reverse Transcription Quantitative PCR (RT-qPCR). In silico, a highly-expressed uncharacterized protein LOC110648447 found in rubber trees was predicted to be a protein in the pathogenesis-related protein 10 (PR-10) class. In silico promoter analysis and structural-related characterization of this novel PR-10 protein suggest that it plays a potential role in defending rubber trees against R. microporus infection. The promoter contains WRKY-, MYB-, and other defense-related cis-acting elements. The structural model of the novel PR-10 protein predicted by I-TASSER showed a topology of the Bet v 1 protein family, including a conserved active site and a ligand-binding hydrophobic cavity. Conclusions A novel protein in the PR-10 group increased sharply in rubber tree leaves during interaction with the white root rot pathogen, potentially contributing to host defense. The results of this study provide information useful for white root rot disease management of rubber trees in the future.

Ficus elastica Roxb. ex Hornem is usually found in tropical and subtropical areas, used in traditional medicine for various health problems, including pain, rheumatism, diarrhea, hypertension, infection, skin allergies, anemia, wound, hernia, and hemorrhoids. This review aims to present the phytoconstituents and pharmacological activities of F. elastica. A literature search employing PubMed, Google Scholar, Semantic Scholar, and Library was done to retrieve the relevant articles. F. elastica is a good source of traditional medicine for the treatment of various types of diseases, especially for microbial infections and preeclampsia. Quercitrin and myricetrin, having strong antioxidant activity, as well as ficusamide, ficusoside B, elastiquinone, elasticoside, and elasticamide are compounds, which have potential to be developed as new drugs for these conditions. In sum, the data regarding the pharmacological and safety aspects of this plant and its components are still limited. However, F. elastica is a natural product that has beneficial to human health and might be a good source for the preparation of new drugs.

Rubber tree is economically important rubber producing plant of Thailand. At present, a rubber tree plantation is susceptible to white root disease. Therefore, the use of rootstock from early introduce clone that proved to be resistant to white root disease could help sustain growing of rubber tree. Thus, the objectives of this research were to study the effects of plant growth regulators and different explants on somatic embryo (SE) induction of this rubber clone and assessment genetic stability. The results revealed that mix flower explant cultured on MS medium supplemented with 2.0 mg/L 6-benzyladenine (BA) and 1.5 mg/L 2,4-Dichlorophenoxyacetic acid (2,4-D) provided callus subsequent somatic embryo (SE) formation at the highest frequency of 39.84 % and number of cotyledonary embryos (CEs) at 3.25 embryos/callus after 3 passages of subculture in the same culture medium (4 weeks/passage). SEs germinated into embryonic axis at 50 % and further development into shoot at 25 % after transfer to 0.25 mg/L GA3 containing MS medium with the best concentrations of BA and 2,4-D for 4 weeks. The assessment gene stability by RAPD and SSR markers showed no variation between mother plant and in vitro plantlets. In this work, a novel explant source - the floral section of the rubber tree - was used for the first time in order to design an effective technique for in vitro somatic embryogenesis. [ABSTRACT FROM AUTHOR]

The rubber tree is an important economic tree in Thailand. Recently, the cultivation of rubber trees in Thailand has suffered from a novel leaf fall disease with diverse symptoms, including leaf spot and leaf blight, resulting in severe leaf defoliation. Fungi from the Lasiodiplodia genus, which causes leaf disease in rubber trees, have not been reported in Thailand. Our research aimed to identify Lasiodiplodia associated with leaf blight disease in Thailand by examining morphological characteristics and completing a multi-gene sequence analysis and pathogenicity test to fulfill Koch's postulates. The internal transcribed spacer regions, translation elongation factor 1-α, and β tubulin 2 were sequenced for the multi-gene sequence analysis. In total, we recovered 14 isolates with 6 of those isolates. Of the six pathogenetic isolates, LST001, LST002, LYT003, LSrt001, and LSrt002 were determined to be Lasiodiplodia chonburiensis, and isolate LYL005 was determined to be L. theobromae. To the best of our knowledge, this is the first report of L. chonburiensis and L. theobromae being associated with leaf blight disease in rubber trees in Thailand or elsewhere. [ABSTRACT FROM AUTHOR]

Brassinolide (BR) is an important plant hormone that regulates the growth and development of plants and the formation of yield. The yield and quality of latex from Hevea brasiliensis are regulated by phytohormones. The understanding of gene network regulation mechanism of latex formation in rubber trees is still very limited. In this research, the rubber tree variety CATAS73397 was selected to analyze the relationship between BR, water deficit resistance, and latex yield. The results showed that BR improves the vitality of rubber trees under water deficit by increasing the rate of photosynthesis, reducing the seepage of osmotic regulatory substances, increasing the synthesis of energy substances, and improving the antioxidant system. Furthermore, BR increased the yield and quality of latex by reducing the plugging index and elevating the lutoid bursting index without decreasing mercaptan, sucrose, and inorganic phosphorus. This was confirmed by an increased expression of genes related to latex flow. RNA-seq analysis further indicated that DEG encoded proteins were enriched in the MAPK signaling pathway, plant hormone signal transduction and sucrose metabolism. Phytohormone content displayed significant differences, in that trans-Zeatin, ethylene, salicylic acid, kinetin, and cytokinin were induced by BR, whereas auxin, abscisic acid, and gibberellin were not. In summary, the current research lays a foundation for comprehending the molecular mechanism of latex formation in rubber trees and explores the potential candidate genes involved in natural rubber biosynthesis to provide useful information for further research in relevant areas. [ABSTRACT FROM AUTHOR]

In order to trace the research history of diseases and pests in rubber tree and explore the potential for their natural control, a bibliometric analysis was conducted based on relevant documents retrieved from the Clarivate Analytics Web of Science (WoS) core collection SCI-E database. VOSviewer software was utilized to analyze the research distribution, scientific collaboration, knowledge structure, and research frontiers. The results show that annual publications on the diseases and pests of rubber tree have increased rapidly after 2005 after a long period of emergence and fluctuation. A total of 624 relevant publications from 51 countries/regions were identified. China was the most productive country with 152 documents, most of which were related to Colletotrichum leaf disease, powdery mildew, and other emerging diseases of rubber tree. France and Brazil produced rich research to tackle South American leaf blight, and have established a close collaborative relationship. Based on the analysis of themes and trend topics, pathogenicity mechanisms of fungal pathogens and plant defense mechanisms are currently hot topics. By further looking into the research, the defense-related genes of rubber tree and antagonistic mechanisms behind candidate biocontrol agents reveal great potential in developing natural control strategies. This study provides a useful reference about the progress and evolution of research into diseases and pests in rubber tree. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to investigate the effect of super absorbent polymers (SAP) on soil biological activities, and dry rubber yield of rubber plantations and find out the optimal application dosage for rubber plantions of dorught-prone regions. This can provide some theoretical basis for the rubber tree drought resistance cultivation technology. [Method] A fifteen-year-old rubber plantion with the clone Reyan 7-33-97 was used to set out a field randomized block experiment and compare the application of different dosages of SAP (0, 60, 120, 180, 300 g/tree) on soil moisture, nutrients, microbial quantity, enzyme activities and the dry rubber yield of the rubber plantation. [Result] The application of super absorbent polymers increased the soil water content and available nutrient content of rubber plantations, but it had no effect on soil pH. At the same time, it significantly promoted the soil bacteria quantity, actinomycetes quantity and total microorganisms, but did not change the overall proportion of bacteria, actinomycetes and fungi in the soil. Soil enzyme activity and rubber latex yield showed a unimodal curve trend with the increase of SAP dosage. The soil bacteria quantity, actinomycetes quantity, soil urease acvitity, invertase acvitity, catalase acvitity, ammonia nitrogen content, available phosphorus content and the yield of dry rubber showed a trend of firstly increase and then decrease with the increase of SAP amount. The T2 treatment was the most effective, in which the soil microorganisms, enzymatic activity and dry rubber yield showed the best. Compared with CK, the quantity of soil bacteria and actinomycetes increased by 346.42% and 191.48%, respectively, while the quantity of soil fungi decreased by 15.31%, and the soil urease activity, invertase activity, and catalase activity increased by 40.01% and 15.74%, 31.44%, respectively, and the yield of the latex increased by 11.99%. [Conclusion] The recommended SAP applicationdosage for the tapping rubber trees is 120 g/tree, which is beneficial to the increase of soil water content, soil microorganisms quantity and soil nutrient contents, as well the promotion of dry rubber yield. [ABSTRACT FROM AUTHOR]

Natural rubber is an important and strategic raw material, used in tires, gloves, and insulating products, that is mainly obtained by cutting the bark of rubber trees. However, the complex contour curve of the rubber tree trunk is hard to fit using a tapping machine. Thus, a trunk contour curve collection would be useful for the development of tapping machines. In this study, an acquisition system based on laser-ranging technology was proposed to collect the point cloud data of rubber tree trunks, and a B-spline fitting program was compiled in Matrix Laboratory (MATLAB) to extract the trunks' contour curves. The acquisition system is composed of power, a controller, a driver, a laser range finder, and data transmission modules. An automatic extraction experiment on the contour curves of rubber tree trunks was carried out to verify the feasibility and accuracy of using the acquisition system. The results showed that the degree of rubber tree trunk characteristic recognition reached 94.67%, which means that the successful extraction of the rubber tree trunk contour curves and the B-spline fitting program are suitable for the extraction of irregular curves of rubber tree trunks. The coefficient of variation of repeated collection was 0.04%, which indicates that changes in relative positions and acquisition directions have little influence on the extraction and the accuracy of the acquisition system, which are high and stable. Therefore, it was unnecessary to adjust the position of the acquisition device before the collecting process, which helped to improve the efficiency of acquisition considerably. The acquisition system proposed in this study is meaningful to the practical production and application of agroforestry and can not only improve the precision of the rubber tapping process by combining with an automatic rubber tapping machine but can also provide technical support for the prediction of rubber wood volume and the development of ring-cutting equipment for other fruit trees. [ABSTRACT FROM AUTHOR]