Hevea Species Research Articles

Pan-genome and phylogenomic analyses highlight Hevea species delineation and rubber trait evolution

The para rubber tree (Hevea brasiliensis) is the world’s sole commercial source of natural rubber, a vital industrial raw material. However, the narrow genetic diversity of this crop poses challenges for rubber breeding. Here, we generate high-quality de novo genome assemblies for three H. brasiliensis cultivars, two H. brasiliensis wild accessions, and three other Hevea species (H. nitida, H. pauciflora, and H. benthamiana). Through analyzing genomes of 94 Hevea accessions, we identify five distinct lineages that do not align with their previous species delineations. We discover multiple accessions with hybrid origins between these lineages, indicating incomplete reproductive isolation between them. Only two out of four wild lineages have been introduced to commercial rubber cultivars. Furthermore, we reveal that the rubber production traits emerged following the development of a large REF/SRPP gene cluster and its functional specialization in rubber-producing laticifers within this genus. These findings would enhance rubber breeding and benefit research communities.

Mitochondrial genome variation and intergenomic sequence transfers in Hevea species.

Among the Hevea species, rubber tree (Hevea brasiliensis) is the most important source of natural rubber. In previous studies, we sequenced the complete nuclear and chloroplast genomes of Hevea species, providing an invaluable resource for studying their phylogeny, disease resistance, and breeding. However, given that plant mitochondrial genomes are more complex and more difficult to assemble than that of the other organelles, little is known about their mitochondrial genome, which limits the comprehensive understanding of Hevea genomic evolution. In this study, we sequenced and assembled the mitochondrial genomes of four Hevea species. The four mitochondrial genomes had consistent GC contents, codon usages and AT skews. However, there were significant differences in the genome lengths and sequence repeats. Specifically, the circular mitochondrial genomes of the four Hevea species ranged from 935,732 to 1,402,206 bp, with 34-35 unique protein-coding genes, 35-38 tRNA genes, and 6-13 rRNA genes. In addition, there were 17,294-46,552 bp intergenomic transfer fragments between the chloroplast and mitochondrial genomes, consisting of eight intact genes (psaA, rrn16S, tRNA-Val, rrn5S, rrn4.5S, tRNA-Arg, tRNA-Asp, and tRNA-Asn), intergenic spacer regions and partial gene sequences. The evolutionary position of Hevea species, crucial for understanding its adaptive strategies and relation to other species, was verified by phylogenetic analysis based on the protein-coding genes in the mitochondrial genomes of 21 Malpighiales species. The findings from this study not only provide valuable insights into the structure and evolution of the Hevea mitochondrial genome but also lay the foundation for further molecular, evolutionary studies, and genomic breeding studies on rubber tree and other Hevea species, thereby potentially informing conservation and utilization strategies.

Morphophysiological indicators applied for the selection of different genotypes of Hevea spp. during germination and post-germination

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.

Differential expression and structural polymorphism in rubber tree genes related to South American leaf blight resistance

South American leaf blight (SALB) is the worst impairment for rubber tree cultivation in the Amazon. Hevea brasiliensis clones produce high latex yields but most are SALB-susceptible (SS). So, resistance has been searched in related species. We selected defense related genes among those differentially expressed while contrasting SALB-resistant (SR) and susceptible clones from three Hevea species. SS clones over-expressed pathways responsive to salicylic (SA) and also jasmonic acid, thus entering a self-harmful cycle. SR clones displayed tightly coordinated SA-responsive and stress-control pathways. Polymorphism in the selected gene sequences supported SS × SR clone divergence.

Exploration of stem endophytic communities revealed developmental stage as one of the drivers of fungal endophytic community assemblages in two Amazonian hardwood genera

Many aspects of the dynamics of tropical fungal endophyte communities are poorly known, including the influence of host taxonomy, host life stage, host defence, and host geographical distance on community assembly and composition. Recent fungal endophyte research has focused on Hevea brasiliensis due to its global importance as the main source of natural rubber. However, almost no data exist on the fungal community harboured within other Hevea species or its sister genus Micrandra. In this study, we expanded sampling to include four additional Hevea spp. and two Micrandra spp., as well as two host developmental stages. Through culture-dependent and -independent (metagenomic) approaches, a total of 381 seedlings and 144 adults distributed across three remote areas within the Peruvian Amazon were sampled. Results from both sampling methodologies indicate that host developmental stage had a greater influence in community assemblage than host taxonomy or locality. Based on FunGuild ecological guild assignments, saprotrophic and mycotrophic endophytes were more frequent in adults, while plant pathogens were dominant in seedlings. Trichoderma was the most abundant genus recovered from adult trees while Diaporthe prevailed in seedlings. Potential explanations for that disparity of abundance are discussed in relation to plant physiological traits and community ecology hypotheses.

Potential Genotypes of the 1995 RRIM Hevea Germplasm Collection for Future Rubber Breeding and Selection Programme

Malaysia received a large share of the Hevea germplasm collection from the 1995 Rubber Research Institute of Malaysia (RRIM) expedition. About 50,000 wild genotypes of eight Hevea species originating from the state of Amazonas of Brazil are conserved ex-situ in Rantau Panjang Reserve Forest, Batu Arang, Selangor. As management of such massive numbers of individuals covering extensive areas is demanding, the wild genotypes planted in this germplasm are evaluated in a phased manner. A total of 5,789 wild genotypes of six Hevea species (Hevea brasiliensis, Hevea spruceana, Hevea guainensis, Hevea nitida, Hevea benthamiana and Hevea pauciflora) originating from different locations in the Amazonas, planted in Phase 1 area (58.88 ha) of this germplasm were assessed for their main characteristics specifically latex yield, clear bole volume, girth at opening, annual girth increment and virgin bark thickness. In general, the wild genotypes of the 1995 RRIM Hevea germplasm produced a considerably low amount of latex yield. Up to 80.84% of these materials were found to produce latex yield of less than 25.00 g/t/t. Nevertheless, Hevea brasiliensis demonstrated superiority compared with the other five Hevea species in this germplasm. Selection of potential genotypes in this germplasm was to gather good performance genotypes as well as to retain as much genetic variability possible. This process was performed using multiple characteristics selection index on latex yield, clear bole volume and girth at opening. The selection process resulted in a working collection consisting 616 potential genotypes of mainly Hevea brasiliensis. Assessment of major leaf diseases revealed that most of the selected genotypes were free from or only lightly affected by Oidium and Colletotrichum secondary leaf fall while all of them were completely free from Corynespora leaf disease and Fusicoccum leaf blight. These selected materials will be used for further evaluation, genetic improvement and incorporation in the Malaysian Rubber Board’s rubber breeding programme for the development of superior latex timber clones.

De novo hybrid assembly of the rubber tree genome reveals evidence of paleotetraploidy in Hevea species

Para rubber tree (Hevea brasiliensis) is an important economic species as it is the sole commercial producer of high-quality natural rubber. Here, we report a de novo hybrid assembly of BPM24 accession, which exhibits resistance to major fungal pathogens in Southeast Asia. Deep-coverage 454/Illumina short-read and Pacific Biosciences (PacBio) long-read sequence data were acquired to generate a preliminary draft, which was subsequently scaffolded using a long-range “Chicago” technique to obtain a final assembly of 1.26 Gb (N50 = 96.8 kb). The assembled genome contains 69.2% repetitive sequences and has a GC content of 34.31%. Using a high-density SNP-based genetic map, we were able to anchor 28.9% of the genome assembly (363 Mb) associated with over two thirds of the predicted protein-coding genes into rubber tree’s 18 linkage groups. These genetically anchored sequences allowed comparative analyses of the intragenomic homeologous synteny, providing the first concrete evidence to demonstrate the presence of paleotetraploidy in Hevea species. Additionally, the degree of macrosynteny conservation observed between rubber tree and cassava strongly supports the hypothesis that the paleotetraploidization event took place prior to the divergence of the Hevea and Manihot species.

Improving spatial transferability of ecological niche model of Hevea brasiliensis using pooled occurrences of introduced ranges in two biogeographic regions of India

Improved spatial transferability of ecological niche models is crucial for accurately predicting species preferred habitat; this is especially true for a planted tree species (Hevea brasiliensis Muell. Arg.). Amazonian valley of South America (AZ) is known as native range of this species. To test the transferability of Maxent ecological niche model among two distinct bio-geographical regions of India, Western Ghats (WG) and North-East (NE) regions and AZ, the present study was designed. The present spatial distribution of H. brasiliensis was evaluated using the Maxent algorithm using bioclimatic variables and species occurrence data from respective regions. An alternate approach of calibrating the model with pooled occurrence points of various introduced ranges of the species was adapted for predicting the species' presence in unsampled region.Spatial distribution of Hevea species in two biogeographic regions of India modelled by Maxent was found to be quite accurate when the model was calibrated with the sampled occurrence points of the same region as evidenced from our previous studies. However, the present study addresses the issue related to transferability of niche based model to predict the probable distribution of Hevea species in an unsampled region based on either its native or introduced range of the species. The result indicates that transferability depends on the extent of similarity between the climatic spaces occupied by the species in sampled region and unsampled regions of the species' distribution. The spatial transferability of the model was improved by using pooled occurrence data of the species from both introduced regions.

Familial hypertryptasemia with associated mast cell activation syndrome

Familial hypertryptasemia with associated mast cell activation syndrome

Evaluation of Rubber Tree Crown Clones for Yield and Magnesium Use Efficiency in a Xanthic Ferralsol

The cultivation of rubber trees in the humid tropical Amazon region is only possible with the use of crown grafts with species of Hevea sp. that are resistant to South American leaf blight – (SALB) [Microcyclus ulei (P. Henn.) v. Arx.]. However, it has been observed that plants with grafted crowns are not efficient in remobilizing magnesium from the crown to the latex. The experimental design was a randomized block, with three replicates. Five crown clones were studied (CPAA C 01, CPAA C 06, CPAA C 18, CPAA C 45, and CBA 2) with two magnesium (Mg) levels [source: magnesium sulfate(MgSO4): low-Mg (150 g plant−1 of MgSO4 × 7H2O] and high-Mg (450 g plant−1 of MgSO4 × 7H2O). The panel clone used for tapping was CNS AM 7905 (Hevea brasiliensis). The results showed that the Mg levels influenced the crown clones differently in relation to yield, efficiency index and leaf and soil Mg concentration. Clone CPAA C 01 with a high-Mg produced over 2.0 t ha−1 of dry rubber. Clones CPAA C 01 and CPAA C 45 were the most efficient, while clone CPAA C 06 showed moderate efficiency and clones CPAA C 18 and CBA 2 were inefficient in using Mg. The Mg concentration in the latex was not influenced by the two Mg levels, with the only differences being between the crown clones.

Leaf-, panel- and latex-expressed sequenced tags from the rubber tree (Hevea brasiliensis) under cold-stressed and suboptimal growing conditions: the development of gene-targeted functional markers for stress response.

Hevea brasiliensis is a native species of the Amazon Basin of South America and the primary source of natural rubber worldwide. Due to the occurrence of South American Leaf Blight disease in this area, rubber plantations have been extended to suboptimal regions. Rubber tree breeding is time-consuming and expensive, but molecular markers can serve as a tool for early evaluation, thus reducing time and costs. In this work, we constructed six different cDNA libraries with the aim of developing gene-targeted molecular markers for the rubber tree. A total of 8,263 reads were assembled, generating 5,025 unigenes that were analyzed; 912 expressed sequence tags (ESTs) represented new transcripts, and two sequences were highly up-regulated by cold stress. These unigenes were scanned for microsatellite (SSR) regions and single nucleotide polymorphisms (SNPs). In total, 169 novel EST-SSR markers were developed; 138 loci were polymorphic in the rubber tree, and 98 % presented transferability to six other Hevea species. Locus duplication was observed in H. brasiliensis and other species. Additionally, 43 SNP markers in 13 sequences that showed similarity to proteins involved in stress response, latex biosynthesis and developmental processes were characterized. cDNA libraries are a rich source of SSR and SNP markers and enable the identification of new transcripts. The new markers developed here will be a valuable resource for linkage mapping, QTL identification and other studies in the rubber tree and can also be used to evaluate the genetic variability of other Hevea species, which are valuable assets in rubber tree breeding.Electronic supplementary materialThe online version of this article (doi:10.1007/s11032-014-0095-2) contains supplementary material, which is available to authorized users.

Impact of an intragenic retrotransposon on the structural integrity and evolution of a major isoprenoid biosynthesis pathway gene in Hevea brasiliensis

Isoprenoids belong to a large family of structurally and functionally different natural compounds found universally from prokaryotes to higher animals and plants. In Hevea brasiliensis, the commercially important cis-polyisoprene (rubber) is synthesised as part of its defence mechanism in addition to other common isoprenoids like phytosterols, growth hormones etc. Farnesyl diphosphate synthase (FDPS) is a key enzyme in this process which catalyses the conversion of isoprene units into polyisoprene. Although prior sequence information is available, the structural variants of the FDPS gene presently existing in Hevea population are largely unknown. Since gene structure has a major role in gene regulation, extensive sequence analysis of this gene from different genotypes was carried out to identify the prevailing structural variants. We identified several SNPs and large indels which were associated with a partial transposable element (TE). Modification of key regulatory motifs and splice sites induced by the retroelement was also identified in the first intron. Screening of popular rubber clones, wild germplasm accessions and Hevea species revealed that the retroelement is responsible for the generation of new alleles with varying degrees of sequence homology. Segregation analysis of a progeny population confirmed that the alleles are not paralogs and are inherited in a Mendelian mode. Our findings suggest that the first intron of the FDPS gene has been subjected to various chromosomal rearrangements due to the interaction of a retrotransposon, resulting in novel alleles which may substantially contribute towards the evolution of this major gene in rubber. Moreover, the results indicate the possible existence of a retrotransposon-mediated epigenetic gene regulatory mechanism in Hevea.

Development, characterization, genetic diversity and cross-species/genera transferability of ILP markers in rubber tree (Hevea brasiliensis)

To construct a linkage map enriched with tapping panel dryness (TPD)-related markers, we firstly utilized rubber tree ESTs associated with TPD to develop intron length polymorphism (ILP) markers. In this study, 52 new ILP markers were further developed. Together with the ILP markers previously reported, 102 ILP markers developed from TPD-related ESTs were analyzed within 39 Hevea germplasm in detail. The PCR success rate and polymorphism rate of ILP markers was 97.06 and 61.62 %, respectively. The results based on PCR amplification and sequence analyses provided the evidences on cross-species/genera transferability of rubber tree ILP markers. The average polymorphic information content (PIC) values of 39 Hevea germplasm were about 0.1719, indicating that the genetic base of Hevea germplasm selected in this study was very narrow. Among 39 Hevea germplasm, the PIC value of wild rubber tree accessions was the highest, followed by Hevea species and cultivated rubber tree clones. Based on the similarity coefficient of ILP markers, 39 Hevea germplasm were divided into three groups including cultivated clones, wild accessions and Hevea species, suggesting that the classification was generally related to the characterization of Hevea germplasm. The ILP markers developed in this study further enriches the number of molecular marker in rubber tree, and the ILP markers will have a wide application in DNA fingerprinting, genetic diversity, marker-assisted selection and genetic mapping, etc. Moreover, the ILP markers transferred cross-euphorbiaceae family might be utilized in cassava, castor bean and physic nut.

Some ethylene biosynthesis and AP2/ERF genes reveal a specific pattern of expression during somatic embryogenesis in Hevea brasiliensis

BackgroundEthylene production and signalling play an important role in somatic embryogenesis, especially for species that are recalcitrant in in vitro culture. The AP2/ERF superfamily has been identified and classified in Hevea brasiliensis. This superfamily includes the ERFs involved in response to ethylene. The relative transcript abundance of ethylene biosynthesis genes and of AP2/ERF genes was analysed during somatic embryogenesis for callus lines with different regeneration potential, in order to identify genes regulated during that process.ResultsThe analysis of relative transcript abundance was carried out by real-time RT-PCR for 142 genes. The transcripts of ERFs from group I, VII and VIII were abundant at all stages of the somatic embryogenesis process. Forty genetic expression markers for callus regeneration capacity were identified. Fourteen markers were found for proliferating calli and 35 markers for calli at the end of the embryogenesis induction phase. Sixteen markers discriminated between normal and abnormal embryos and, lastly, there were 36 markers of conversion into plantlets. A phylogenetic analysis comparing the sequences of the AP2 domains of Hevea and Arabidopsis genes enabled us to predict the function of 13 expression marker genes.ConclusionsThis first characterization of the AP2/ERF superfamily in Hevea revealed dramatic regulation of the expression of AP2/ERF genes during the somatic embryogenesis process. The gene expression markers of proliferating callus capacity to regenerate plants by somatic embryogenesis should make it possible to predict callus lines suitable to be used for multiplication. Further functional characterization of these markers opens up prospects for discovering specific AP2/ERF functions in the Hevea species for which somatic embryogenesis is difficult.

Genetic diversity of cultivated accessions and wild species of rubber tree using EST‑SSR markers

The objective of this work was to evaluate the efficiency of EST‑SSR markers in the assessment of the genetic diversity of rubber tree genotypes (Hevea brasiliensis) and to verify the transferability of these markers for wild species of Hevea. Forty‑five rubber tree accessions from the Instituto Agronômico (Campinas, SP, Brazil) and six wild species were used. Information provided by modified Roger's genetic distance were used to analyze EST‑SSR data. UPGMA clustering divided the samples into two major groups with high genetic differentiation, while the software Structure distributed the 51 clones into eight groups. A parallel could be established between both clustering analyses. The 30 polymorphic EST‑SSRs showed from two to ten alleles and were efficient in amplifying the six wild species. Functional EST‑SSR microsatellites are efficient in evaluating the genetic diversity among rubber tree clones and can be used to translate the genetic differences among cultivars and to fingerprint closely related materials. The accessions from the Instituto Agronômico show high genetic diversity. The EST‑SSR markers, developed from Hevea brasiliensis, show transferability and are able to amplify other species of Hevea.

Microsatellite marker development for the rubber tree (Hevea brasiliensis): characterization and cross-amplification in wild Hevea species

BackgroundThe rubber tree (Hevea brasiliensis) is native to the Amazon region and it is the major source of natural rubber in the world. Rubber tree breeding is time-consuming and expensive. However, molecular markers such as microsatellites can reduce the time required for these programs. This study reports new genomic microsatellite markers developed and characterized in H. brasiliensis and the evaluation of their transferability to other Hevea species.FindingsWe constructed di- and trinucleotide-enriched libraries. From these two libraries, 153 primer pairs were designed and initially evaluated using 9 genotypes of H. brasiliensis. A total of 119 primer pairs had a good amplification product, 90 of which were polymorphic. We chose 46 of the polymorphic markers and characterized them in 36 genotypes of H. brasiliensis. The expected and observed heterozygosities ranged from 0.1387 to 0.8629 and 0.0909 to 0.9167, respectively. The polymorphism information content (PIC) values ranged from 0.097 to 0.8339, and the mean number of alleles was 6.4 (2–17). These 46 microsatellites were also tested in 6 other Hevea species. The percentage of transferability ranged from 82% to 87%. Locus duplication was found in H. brasiliensis and also in 5 of other species in which transferability was tested.ConclusionsThis study reports new microsatellite markers for H. brasiliensis that can be used for genetic linkage mapping, quantitative trait loci identification and marker- assisted selection. The high percentage of transferability may be useful in the evaluations of genetic variability and to monitor introgression of genetic variability from different Hevea species into breeding programs.

Development of microsatellite molecular markers and genetic diversity in Hevea Braziliensis

Background The rubber tree [Hevea Braziliensis (Willd. ex Adr. De Juss.) Muell-Arg.] is native from the Amazon region which has great economic importance for being the largest source of natural rubber in the world. Although Brazil is the center of origin and genetic diversity of this culture, the country is currently responsible for only 1% of the world production. Besides offering optimal weather conditions for crop development, the Amazon rainforest region is also favorable to the development of the fungus known as SALB (South American leaf blight), which causes the disease-of-leaves. Leaves fall sharply reducing the production of latex, limiting the production of rubber in this region. Thus breeding programs are seeking for clones which are resistant to this fungus and with high production in escape regions, which provide stress conditions such as low temperatures, high altitude, wind and other diseases [1]. The rubber tree is perennial and requires about 30 years to obtain an improved variety, starting from the controlled pollination of a clone to the final recommendation. Molecular markers such as microsatellites (Simple Sequence Repeats, SSRs) are an important tool for diversity studies and potentially to assist breeding programs. This study aimed to develop an enriched microsatellite library for H. Braziliensis, characterize these developed microsatellite markers and test the transferability of these markers to six other species of the genus Hevea. Material and methods For this study we used 36 accessions of H. Braziliensis donated by the Agronomy Institute of Campinas and one accession of each of six other species of genus Hevea (H. nitida, H.pauciflora (2), H.camargoana, H.guianensis, H. rigidifolia andH. benthamiana) provided by Embrapa. Genomic DNA samples were extracted from lyophilized leaf tissues using a modified CTAB method [2]. Trinucleotide and dinucleotide enriched genomic libraries for H. Braziliensis were constructed. The DNA samples were digested with AFAI and enriched using (CT)8 and (GT)8 biotinylated microsatellite probes for the dinucleotide library and (ATC)8 and (CCT)8 for the trinucleotide library. The clones obtained were sequenced and the sequences were evaluated with the Microsat program, which removes parts of the vector and the adapters and verifies the presence of restriction site within the sequence. After this step, the sequences were aligned and edited using the program SeqMan (DNAStar Inc.), which also allows analyzing the redundancy of the library. The identification of microsatellites was performed using a research tool SSRs SSRIT – “The Simple Sequence Repeat Identification Tool” avaiable at Gramene [http:// www.gramene.org]and primers complementary to sequences flaking the microsatellites were designed by Primer Select Program (DNAStar Inc) and Primer 3. Amplification tests were made from a temperature gradient to know the annealing temperature and the products were evaluated and resolved on 3% agarose gels stained with ethidium bromide and in denaturing 6% polyacrylamide and silver stained [3]. The loci were characterized on the number of alleles per locus, allele frequency and the Polymorph Information Content (PIC). It was also made analysis of ancestry for de accessions of H. Braziliensis using the program Structure v 2.3.3 [4]. * Correspondence: camila.mantello@gmail.com Molecular Genetic Analysis Laboratory Molecular Biology Center and Genetic Engineering (CBMEG), UNICAMP, Campinas, Sao Paulo, 13083-875, Brazil Full list of author information is available at the end of the article Mantello et al. BMC Proceedings 2011, 5(Suppl 7):P11 http://www.biomedcentral.com/1753-6561/5/S7/P11

Development and Characterization of Intron-Flanking EST-PCR Markers in Rubber Tree (Hevea brasiliensis Muell. Arg.)

With a long-term goal of constructing a linkage map enriched with gene-specific markers in rubber tree (Hevea brasiliensis Muell. Arg.), we utilized rubber tree ESTs associated with tapping panel dryness (TPD) to develop intron-flanking PCR markers. After downloading and assembling the rubber tree ESTs associated with TPD, we predicted the exon/exon junction sites (E/E) by aligning rubber tree transcripts with the genomic sequences of castor bean (Ricinus communis L.). Based on the predicted E/E, the primers flanking intron(s) and no intron were designed. Compared with the markers designed by conventional method, the PCR success rate of the markers designed with the predicted E/E increased 28-30%, whereas the polymorphism rate of intron-flanking EST-PCR markers was approximately 3.43-fold increase. Therefore, the intron-flanking marker was more polymorphism-generating efficient than the markers designed by conventional methods. In addition, analyzing the polymorphic information content (PIC) among Hevea germplasm showed that the polymorphism of wild rubber tree accessions was higher than one of cultivated rubber tree clones and Hevea species. This study enriches the categories and numbers of molecular markers in rubber tree, and the markers developed in this research will have a wide application in DNA fingerprinting, marker-assisted selection and genetic mapping in rubber tree. This research also indicates that it is possible to develop intron-flanking EST-PCR markers of rubber tree with castor bean genome as reference sequences, which provides new insights into developing intron-flanking EST-PCR markers for rubber tree or other plant species without genomic information.

EVALUACIÓN DE LA VARIABILIDAD GENÉTICA DE CLONES DE CAUCHO NATURAL PRESENTES EN LA COLECCIÓN CLONAL DEL INSTITUTO SINCHI, MEDIANTE EL USO DE DESCRIPTORES MORFOLÓGICOS

La revista Colombia Forestal publica manuscritos originales en temáticas del campo forestal y diversos aspectos de los recursos naturales y del medio ambiente, los cuales se discriminan en las categorías de artículo de investigación, de revisión, de reflexión y notas técnicas de acuerdo con lo estipulado por COLCIENCIAS para las publicaciones científicas. De acuerdo a la clasificación de áreas científicas de la Organización para la Cooperación y el Desarrollo Económico (OCDE), la revista Colombia Forestal pertenece al gran área de Ciencias Agrícolas(4), área de Agricultura, Silvicultura y Pesca(4A) y a la disciplina Forestal (4A02).

Microsatellites from rubber tree (Hevea brasiliensis) for genetic diversity analysis and cross-amplification in six Hevea wild species

Hevea brasiliensis is native to the Amazonian rain forest and an important source of natural rubber. Twenty seven polymorphic microsatellite loci were isolated and characterized from a GA–CA enriched genomic library of H. brasiliensis. The number of alleles ranged from 2 to 20. The observed and expected heterozygosity ranged from 0.13 to 0.88 and from 0.00 to 0.89, respectively. Cross-species amplification of the markers developed for H. brasiliensis was successful in the wild Hevea species H. guianensis, H. rigidifolia, H. nitida, H. pauciflora, H. benthamiana and H. camargoana. The data indicated a high degree of sequence homology in the microsatellite flanking regions of these species. The developed SSR loci are a potential powerful tool for studies of population genetics, genetic diversity and gene flow among Hevea species.