Coconut Leaf Research Articles

Mechanical Behavior of Arbitrarily Reinforced Cocos Nucifera Leaf Sheath Fibre Reinforced Polyester Composites – Comparison with other Coconut FRP Composites

Coconut trees are extensively grown in Kerala and Godavari districts and in few locations of Andhra Pradesh. Fibres are extracted from various parts of coconut tree and are exploited by various researchers. In this work an attempt is made to reinforce coconut leaf sheath arbitrarily into polyester matrix. Then the lamina is machined to obtain tensile, flexural and impact test specimens as per ASTM standards. Coconut leaf sheath FRP composites at 12.83%, 11.06% weight fractions have shown tensile strength, modulus of 17.73 MPa, 254.21 MPa respectively. Charpy impact strength of the coconut leaf sheath FRP composites is increased with its content from 1.93 to 5.36 kJ/m2. The results from this experimentation have a cleared that the mechanical performance of the composites is increased with number of layers. So, this kind of light weight composite materials may be used for making various parts of automobile. Further the tested specimens are morphologically examined for understanding the interfacial bonding between fibre and polyester resin. Finally the results of present experimentation are compared with other kinds of coconut fibre reinforced polymer composites in order to estimate the better reinforcements.

Phylogeography and population structure analysis reveals diversity by mutations in Lasiodiplodia theobromae with distinct sources of selection.

Lasiodiplodia theobromae is a plant pathogen with a worldwide distribution, with low host specificity, causing stem cankers, dieback diseases, and fruit rot in several species of plants. In coconut, this pathogen is reported as the etiological agent of "coconut leaf blight" (CLB) disease, causing several losses in fruit production. The CLB is an important disease for this crop in Brazil. In our study, we used a phylogeographic approach through the molecular characterization of the translation elongation factor 1-α (TEF1-α) to elucidate the pathogen distribution in Brazil and other countries, besides, search information about diversity sources of this pathogen in coconut palm tree at Brazilian northern, northeast, and southeast. We found that L. theobromae diversity is within populations (locations), and populations that are located closest to the center of the tropical zone have more variability as Central Africa, Brazilian Southeast, and Northeast. The widespread distribution could be in part related with long-distance dispersal via global trade of plants and plant products. The entrance route of L. theobromae in Brazil probably occurred from Africa route and not occurred once. In Brazil, the diversity of this pathogen in coconut tree could be linked to two agents of selection: high host diversity (in Northeast) and distinct management measures adopted in Southeast. These different sources of selection, mainly the mutations, could be one of the reasons that we found distinct reactions to "coconut leaf blight" chemical control in these regions.

Cross-compatibility evaluation of plant growth promoting rhizobacteria of coconut and cocoa on yield and rhizosphere properties of vegetable crops

Plant growth promoting rhizobacteria (PGPR), Bacillus megaterium TSB16 isolated from coconut and Pseudomonas putida KDSF23 from cocoa, were tested for cross-compatibility with vegetable crops in combination with coconut leaf vermicompost (CLV). The treatments included CLV @10 t/ha (T1), B. megaterium + CLV @ 6 kg /ha and 10 t/ha, respectively (T2), P. putida + CLV @ 6 kg /ha and 10 t/ha, respectively (T3) and recommended dose of NPK fertilizers @75:40:25 kg N, P2O5, K2O + CLV @ 2.5 t/ha (T4). The results of the field trial indicated that the cumulative yield of tomato was significantly higher (P<0.05) with chemical fertilizer application (278.7 g/plant) and Pseudomonas putida KDSF23+ CLV treatment (275.8 g/plant) compared to that in CLV application (239.5 g/plant). The yield of chilli was significantly higher in the plots that received chemical fertilizers. The soil N, P, K and organic carbon were highest in chemical fertilizer applied plots. However, a significant increase in population of rhizosphere microbial communities, particularly the plant-beneficial microbiota, and soil enzyme activities (phosphatase, dehydrogenase and urease) were recorded in the PGPR and CLV treated plots. The function-specific microorganisms viz. fluorescent pseudomonads, phosphate solubilizers, free-living nitrogen fixers and Trichoderma were 4.7–9.1, 3.5–3.8, 1.3–2.1 and 2.0–2.2 fold higher, respectively, in tomato and 1.5–1.6, 1.4–2.5, 1.3–1.4 and 2.9–3.4 fold higher, respectively, in chilli, in PGPR treated plots than that received chemical fertilizer. Our findings suggest that the PGPR strains isolated from the rhizosphere of coconut and cocoa can be utilized as a bioinoculant for vegetable production in organic agricultural systems indicating cross-compatible nature. They can also serve as a single bioinoculant for the main crop (coconut) and its intercrops (such as vegetables) in coconut based cropping system to reduce inorganic fertilizer application.

Genome Sizes of Nine Insect Species Determined by Flow Cytometry and k-mer Analysis.

The flow cytometry method was used to estimate the genome sizes of nine agriculturally important insects, including two coleopterans, five Hemipterans, and two hymenopterans. Among which, the coleopteran Lissorhoptrus oryzophilus (Kuschel) had the largest genome of 981 Mb. The average genome size was 504 Mb, suggesting that insects have a moderate-size genome. Compared with the insects in other orders, hymenopterans had small genomes, which were averagely about ~200 Mb. We found that the genome sizes of four insect species were different between male and female, showing the organismal complexity of insects. The largest difference occurred in the coconut leaf beetle Brontispa longissima (Gestro). The male coconut leaf beetle had a 111 Mb larger genome than females, which might be due to the chromosome number difference between the sexes. The results indicated that insect invasiveness was not related to genome size. We also determined the genome sizes of the small brown planthopper Laodelphax striatellus (Fallén) and the parasitic wasp Macrocentrus cingulum (Brischke) using k-mer analysis with Illunima Solexa sequencing data. There were slight differences in the results from the two methods. k-mer analysis indicated that the genome size of L. striatellus was 500–700 Mb and that of M. cingulum was ~150 Mb. In all, the genome sizes information presented here should be helpful for designing the genome sequencing strategy when necessary.

Limitation in the use of spectral analysis to detect Weligama coconut leaf wilt disease affected palms in Southern Sri Lanka

Weligama Coconut Leaf Wilt Disease (WCLWD) was first reported in late 2006 in the Weligama Divisional Secretariat Division (DSD) in Matara District in the Southern Province of Sri Lanka. Surveys conducted in 2012 revealed that 65,838, 251,980 and 14,344 palms affected by the disease in Galle, Malara and Hambanlota districts respectively. It has been confirmed by the Coconut Research Institute that the disease is caused by a phytoplasma which has some resemblance to the phytoplasma of Coconut Root (Wilt) disease in India. A 3 km wide boundary was demarcated covering the area affected by the disease and all suspicious palms were removed in the boundary zone. In the core area, affected palms were gradual removed. The disease prevailing area spanned &gt; 680 km2 and the detection of affected coconut palms across such a large area became practically difficult. Therefore, the objective of the present study was to find alternative methods to detect affected coconut palms with yellowing leaves prominent at the middle stage of the disease, using multispectral satellite images of 0.5 m resolution. It was envisaged to use this technique as a supportive management tool at field level, if successful. Normalized Differential Vegetation Index (NDVI) which is the standard and widely used algorithm for detecting vegetation under stress conditions did not reveal an appreciable isolation of canopies of affected coconut palms. Of the different customized algorithms tested, the best outcome was obtained by the algorithm (Red + Green) - 2 x (Blue). When this algorithm was applied to the multispectral satellite images of 0.5 m resolution in the affected area, adult coconut palms in advanced stage of the disease could be distinguished with an accuracy of above 80%. However, a detection of palms in the early stages of the disease where leaf flaccidity is the major morphological symptom could not be made with an acceptable level of accuracy. Moreover, the detection of affected coconut seedlings was much more difficult. Thus, only an overall accuracy of 60 - 70% could be achieved by this approach with multispectral satellite images of 0.5 m resolution. Although the level of accuracy is not sufficient for a comprehensive field level application, there is scope for further improvement using images with higher resolution.

A survey of land for Weligama coconut leaf wilt disease affected palms outside the declared boundary in the Southern Province

After the identification of the Weligama Coconut Leaf Wilt Disease (WCLWD) in 2006, a three km wide boundary zone was declared which stretched from Galle to Tangalle. All suspicious palms recorded within the boundary zone were removed. Gradual removal of affected palms in the core area was also continued. These actions along with many other precautionary steps were taken with the objective to prevent the spread of the disease further beyond the demarcated boundary. After taking continued precautionary measures for more than 7 years, it was timely to find out the presence of any disease affected palms beyond the boundary. Therefore, a sample survey was conducted along a 4 km wide belt beyond the boundary. Uniform sampling locations were ensured by selecting sample sites on a I km grid drawn on the areal image of the area. Each grid covered an area of I km2 (100 ha). Four sampling locations/plots of approximately I ha in extent were selected within each grid. All coconut palms within selected plots were examined for morphological symptoms of the WCLWD and necessary information was recorded. The total area covered by the sample survey was about 40,000 ha and the extent closely examined was about 1600 ha, which was approximately 4% of the total land area covered by the survey. The results revealed that the precautionary measures taken by relevant authorities to prevent the spread of the WCLWD have had a significant effect in containing the disease within the demarcated area. However, some spread of the disease beyond the boundary was detected in a few places within the four-km-belt beyond the boundary. Thus altogether 18 affected palms were identified in 10 plots in Galle and Malara districts. They were in Akmeemana, Imaduwa and Yakkalamulla DSD in Galle district and Kamburupitiya and Mulatiyana DSD in Malara district. Most of those locations were adjacent to the boundary. However, any detection of even a few affected palms outside the boundary in a sample survey indicates the possibility of having such palms elsewhere in the study area. A comprehensive palm to palm survey is needed for precise detection of such palms. Considering the impending threat from the disease, a palm to palm survey at least within a 4 km belt outside the boundary is suggested to effectively prevent the spread of the disease, despite the cost and the man power required for such an operation.

Evaluation of coconut germplasm in Weligama and Matara area of the Southern Province of Sri Lanka for resistance to Weligama coconut leaf wilt disease

Weligama Coconut Leaf Wilt Disease has been reported to infect the coconut palms in Southern Sri Lanka. Intra-cellular pathogen phytoplasma has been identified as the causal organism of this disease. So far there have been no known control methods to cure diseases caused by intra-cellular pathogens. Integration of resistant varieties into management programmes has been identified as a viable option in management strategies of such diseases. For this, it is essential to identify the resistance of available genetic resources. This study was carried out in the Weligama and Matara area of Southern Sri Lanka to screen the coconut germplasm for resistance to Weligama Coconut Leaf Wilt Disease. Infected and healthy palms were differentiated using symptomatology; flaccidity of leaves, yellowing of leaves and marginal necrosis of leaflets. Sri Lanka Tall, Sri Lanka Green and yellow dwarfs, Gon thembili tall and king coconut were among the main coconut forms studied. Out of them Sri Lanka Green Dwarf recorded a high level of resistance (98%). Within the Sri Lanka Yellow dwarf and Gon thembili tall, certain individual genotypes were observed to be resistant while king coconut was identified to be susceptible. The most popular commercial coconut variety, Sri Lanka tall was highly susceptible to the disease although there were certain individual genotypes which were resistant. Although Sri Lanka Green dwarf has not so far been viable as a commercial coconut cultivar the presence of resistant genes within the coconut germplasm was recognized as a great advantage in breeding coconuts for resistance to Weligama Coconut Leaf Wilt Disease.

Comparative Evaluation of Sri Lanka Tall and Dwarf x Tall Coconut Hybrids for Tolerance to Weligama Coconut Leaf Wilt Disease in Sri Lanka

Weligama Coconut Leaf Wilt Disease (WCLWD) is a phytoplasma disease found in Southern Sri Lanka. It is an incurable, debilitating disease resulting in yield loss and ultimate death of the palm and over 250,000 palms have been identified to be infected. Breeding coconuts for resistance is a viable option in managing incurable diseases and for this WCLWD resistant germplasm is needed. Accordingly, the objective of the current research was to investigate the comparable levels of WCLWD resistance of Sri Lanka tall and CRIC65 coconut cultivars which are favoured in Sri Lanka.&#x0D; Eight coconut estates which were planted with Sri Lanka tall (SLT) and CRIC65 hybrids as a mixed plantation or in close proximity were observed. Out of them an extent of about 04 acres of one estate was selected for detailed analysis using the disease severity index developed based on the WCLWD symptoms; flaccidity, leaf yellowing and marginal necrosis of leaflets.&#x0D; General observations indicated the presence of WCLWD in both SLT and the hybrid CRIC65. Marginal necrosis was at a minimal level in both the cultivars, while the other symptoms; flaccidity and yellowing scored higher values at all levels in the spiral in SLT than in hybrid CRIC65. Moreover, the hybrid coconut CRIC65 displayed lower percentage of disease incidence and significant reduction in the levels of the main symptom flaccidity. As a result, the hybrid palms recorded significantly low disease index value than SLT. Moreover, disease incidence was observed to be low in properly managed estates irrespective of the cultivar. With the findings of the current study, coconut varieties SLGD and selected SLT which remain healthy under the same disease pressure can be recommended as parents in a breeding programme aiming at resistance/tolerance to WCLWD.

THE DERBID PLANTHOPPER PROUTISTA MOESTA (WESTWOOD) (HEMIPTERA: FULGOROIDEA) ON OIL PALM IN PAPUA NEW GUINEA

Derbidae are one of the largest families among the Fulgoroidea, and species are often found on many palm species such as Areca, Cocos and Elaeis. The first record of Proutista moesta (Westwood) is given for Papua New Guinea (Northern Province). The distribution and aspects of the biology are discussed. Keywords: Oil palm, insect pests, Proutista moesta, vectors, lethal yellowing disease, Kerala wilt disease, Weligama coconut leaf wilt.

Molecular Identification of Bacterial Pathogen Infecting Coconut Leaf Beetle

&lt;p&gt;&lt;span style="font-size: medium;"&gt;ABSTRACT &lt;/span&gt;&lt;/p&gt;&lt;p&gt;Many species of microorganisms can cause diseases and mortality of insect pests. Accurate detection and identification of the entomophatogens are essential for development of biological control agent to the pest. Brontispa longissima, a serious and invasive pest of coconut, was infected by bacterium causing mortality of the larvae and pupae in coconut field. Objective of the research was to identify bacterium as a causal agent of the field-infected B. longissima using molecular technique. Research was conducted between April and August 2011. Molecular identification using polymerase chain reaction (PCR) amplification of 16s ribosomal RNA of the infected larvae and sequencing of the gene showed that Serratia marcescens is the causal agent of the disease.&lt;/p&gt;&lt;p&gt;Keywords: Brontispa longissima, coconut, 16s rRNA, Serratia marcescens.&lt;/p&gt;&lt;p&gt; &lt;/p&gt;&lt;p&gt;&lt;span style="font-size: medium;"&gt;Identifikasi Molekular Bakteri Pathogen yang Menginfeksi Hama Daun Kelapa &lt;br /&gt;Brontispa longissima(Coleoptera:Chrysomelidae)&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span style="font-size: medium;"&gt;ABSTRAK &lt;/span&gt;&lt;/p&gt;&lt;p&gt;Banyak mikroorganisme dapat menimbulkan penyakit pada serangga hama. Deteksi dan identifikasi yang akurat dari pathogen penyebab penyakit pada serangga (entomopathogen) hama merupakan tahap yang penting dalam pengembangan pengendalian biologi untuk hama tersebut. Brontispa longissima sebagai hama penting dan bersifat invasif pada tanaman kelapa diinfeksi oleh sejenis bakteri yang menyebabkan kematian larva dan pupa dari serangga tersebut di lapangan. Penelitian ini bertujuan untuk mengidentifikasi organisme penyebab penyakit pada hama B. longissima dengan menggunakan teknik molekuler. Penelitian dilaksanakan pada bulan April sampai dengan Agustus 2011. Identifikasi bakteri dilakukan dengan mengamplifikasi 16s ribosomal RNA dari larva yang terinfeksi dengan menggunakan PCR (polymerase chain reaction). Hasil analisis sekuens nukleotida 16s ribosomal RNA dari larva yang terinfeksi menunjukkan bahwa Serratia marcescens adalah bakteri penyebab dari penyakit tersebut.&lt;/p&gt;&lt;p&gt;Kata kunci: Brontispa longissima, kelapa, 16s rRNA, Serratia marcescens.&lt;/p&gt;

Identification and utilization of informative EST-SSR markers for genetic purity testing of coconut hybrids

&lt;p&gt;Coconut palms are categorized into two forms, &lt;em&gt;viz&lt;/em&gt;., ‘talls’ and ‘dwarfs’ which are being utilized to produce hybrids through the process of inter-varietal or intra-varietal crosses. Hybrid coconut seedlings are generally identified and selected based on morphological traits by plant breeders, which is quite difficult and requires expertise. Even minor errors in identification may adversely affect breeding programs in coconut, which is spread over many decades. In this study, we have utilized thirty EST-SSR markers, derived from existing coconut leaf transcriptome data, for screening polymorphism between eighteen coconut parental lines. The polymorphic primers capable of differentiating the parental palms were then utilized successfully for assessment of purity of hybrids derived from these parents. Thus, the current study demonstrates the utility of EST-SSR markers in determining&lt;br /&gt;the genetic purity of hybrids in coconut.&lt;/p&gt;

Biological and physiological response of a tropical parasitoid, Tetrastichus brontispae (Ferriere) following exposure to low temperature

Tetrastichus brontispae Ferriere (Hymenoptera: Eulophidae) is an important natural enemy of the coconut leaf beetle Brontispa longissima (Gestro), a serious invasive pest on palm plants. Exposure to low temperature (2 °C) for 4, 24 and 48 h had an adverse effect on biological performance (survival, parasitism rate) of T. brontispae with immature parasitoids (eggs, larvae, and pupae) being more sensitive to low temperature than adults. Exposure to 2 °C for 24 h reduced the water content and increased the concentration of glycerol and trehalose, and activity of superoxidae in T. brontispae adults. Analysis of suppression subtractive hybridization indicated the integrative controlling and transcriptome regulation of the networks in the cold stress response of T. brontispae. Our study suggests that the allocation of energy reserves to either prevent or repair cold-induced damage may consume resources that could otherwise be invested in reproduction and consequently its ability to exert control on B. longissima.

Thermal insulating particle boards reinforced with coconut leaf sheaths

This paper studies the potential use of coconut husk particles bonded by castor oil-based polyurethane resin to manufacture low-density thermal insulating particle boards, reinforced on their external surfaces by coconut leaf sheaths naturally available in tropical regions as a textile. Panels with a nominal density of 300 kg/m3 were manufactured, and a resin/particle ratio of 0·2 (by weight) was adopted to ensure the necessary adhesion of the particles. The panels under consideration were: plain coir particle boards without tissue reinforcement; one external side reinforced by one layer of the upper parts of leaf sheaths; both external sides reinforced by one layer of the leaf sheath‘s upper parts (UP2S); and both external sides reinforced by one layer of the leaf sheath‘s bottom parts. The thermal, physical and mechanical properties of the boards were evaluated and the thermal-physical-mechanical results indicated that coconut husk particle boards reinforced on both external sides by the upper part of the coconut textiles (UP2S) can be considered for thermal insulation.

Mechanical and Morphological Study of Arecanut Leaf Sheath (ALS), Coconut Leaf Sheath (CLS) and Coconut Stem Fiber (CSF)

Mechanical and Morphological Study of Arecanut Leaf Sheath (ALS), Coconut Leaf Sheath (CLS) and Coconut Stem Fiber (CSF)

Mechanical and Morphological Study of Arecanut Leaf Sheath (ALS), Coconut Leaf Sheath (CLS) and Coconut Stem Fiber (CSF)

Mechanical and Morphological Study of Arecanut Leaf Sheath (ALS), Coconut Leaf Sheath (CLS) and Coconut Stem Fiber (CSF)

Evaluation of phosphorus availability in a lateritic gravelly, coconut grown and long term phosphate fertilizer applied soil in Sri Lanka with an indicator plant

The residual phosphorus availability and response of Ginger (Zinigiber officinale) to residual available phosphorus in (lateritic gravelly) Red Yellow Podzolic soil (RYP - Rhodustults) of Andigama soil series from Rathmalagara estate, Madampe was evaluated after 10 years of continuous application of 03 sources of phosphates to young coconut palms. A pot experiment was established using Andigama soil series which was collected from field experimental site where coconut palms were treated with 03 levels of phosphate with 03 different phosphate sources i.e., Eppawela Rock Phosphate (ERP, 30 % P2O5), Imported Rock Phosphate (1RP, 27.5% P205) and Triple Super Phosphate (TSP, 46 % P205) from the seedling stage up to the age of 10 years. The initial rates of phosphate applications were P205 equivalent of 50, 100 and 200 g palnrf'year'1 respectively which were annually increased by 5, 10 and 20 g respectively. Ginger was used as an indicator plant as the growth parameters, yield and the total P content in the ginger can be taken as an indication of the response to different treatments. Ginger rhizomes were planted in pots filled with 5 kg of phosphate treated soil and all the plants were treated with a basal dose of nitrogen (N) and potassium (K.) at every 1 V2 month intervals for 6 months. Number of tillers per bush, height of the plants and number of leaves in bush in each pot were recorded. Six months after planting, ginger plants were uprooted and fresh and dry weight of shoots of the plants, roots and rhizomes were recorded. All the plant parts were analysed for total P. Soil samples were collected before planting the ginger and analyzed for available P by 2.5 % acetic acid method, Olsen’s bicarbonate and Bray and Kurtz 1 method. The overall result showed that the extractable P in soil treated with all 03 levels of ERP, IRP and TSP by 2.5 % HAc-P, Olsen - P and Bray - P values were above the sufficiency soil P values of 7.8 mg kg-1, 8.5 mg kg-1 and 5.8 mg kg-1 respectively. The highest level of TSP, IRP and ERP treatments were significantly effective in increasing the dry weight of rhizomes and the shoots of ginger. It indicated that residual phosphorus availability of TSP, IRP and ERP was high and its effectiveness on response to ginger was more or less similar. This might be due to low dissolution of ERP and fixation of TSP in lateritic gravel soil. According to the findings of this experiment, P fertilizers can be taken out from the coconut fertilizer recommendation for a period of time by monitoring the effectiveness of the residual P status in soil and coconut leaf. Findings of this experiment can be included into site specific fertilizer recommendation programmes of the other perennial crops. By monitoring the availability of P in soil, intercrops can be grown in coconut plantations without application of P fertilizers. COCOS Vol. 20: 59-70 (2013)

Characterization of gibberellin 2-oxidase isoforms in coconut (Cocos nucifera L.)

&lt;span style="line-height: 107%; font-family: 'Times New Roman','serif'; font-size: 12pt; mso-bidi-language: HI; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-ansi-language: EN-GB; mso-fareast-language: EN-US;" lang="EN-GB"&gt;Gibberellins (GAs) are plant hormones that are essential for many developmental processes in plants, including seed germination, stem elongation, leaf expansion, trichome development, pollen maturation and the induction of flowering. Gibberellin 2-oxidase (GA2-ox) regulates plant growth by inactivating endogenous bioactive GAs through 2β-hydroxylation. There is no information about &lt;em&gt;GA2-ox &lt;/em&gt;encoding genes or their functions in coconut. In this study, we have identified 10 transcripts encoding different isoforms of GA2-ox from coconut leaf transcriptome data. Sequence comparison and phylogenetic analysis revealed that these 10 transcripts represented different types of GA2-ox. The secondary structure, three dimensional structure and active sites of these 10 isoforms were predicted. Docking studies of different active GAs with these isoforms was also carried out.&lt;/span&gt;

Molecular and Scanning Electron Microscopic Proof of Phytoplasma Associated With Areca Palm Yellow Leaf Disease in Sri Lanka

HomePlant DiseaseVol. 99, No. 11Molecular and Scanning Electron Microscopic Proof of Phytoplasma Associated With Areca Palm Yellow Leaf Disease in Sri Lanka PreviousNext DISEASE NOTES OPENOpen Access licenseMolecular and Scanning Electron Microscopic Proof of Phytoplasma Associated With Areca Palm Yellow Leaf Disease in Sri LankaC. Kanatiwela-de Silva, M. Damayanthi, R. de Silva, M. Dickinson, N. de Silva, and P. UdagamaC. Kanatiwela-de SilvaSearch for more papers by this author, M. DamayanthiSearch for more papers by this author, R. de SilvaSearch for more papers by this author, M. DickinsonSearch for more papers by this author, N. de SilvaSearch for more papers by this author, and P. UdagamaSearch for more papers by this authorAffiliationsAuthors and Affiliations C. Kanatiwela-de Silva , Department of Zoology, Faculty of Science, University of Colombo, Sri Lanka; M. Damayanthi , Sri Lanka Institute of Nanotechnology, Nanotechnology & Science Park, Mahenwatte, Pitipana, Homagama, Sri Lanka; R. de Silva , Crop Protection Division, Coconut Research Institute, Lunuwila, Sri Lanka; M. Dickinson , School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK; N. de Silva , Sri Lanka Institute of Nanotechnology, Nanotechnology & Science Park, Mahenwatte, Pitipana, Homagama, Sri Lanka; and P. Udagama , Department of Zoology, Faculty of Science, University of Colombo, Sri Lanka. Published Online:21 Sep 2015https://doi.org/10.1094/PDIS-01-15-0072-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat The areca palm, Areca catechu L., of the Arecaceae family, is an important commercial crop in the world, where the drupe, commonly called the areca nut, is mainly used in betel quid chewing in many Asian and Oceanic countries. Areca palms have a low commercial value in Sri Lanka; they are largely grown in wet and intermediate zones on a total area of 11,968 ha in home gardens, as mixed cultivations, and seldom as small scale commercial cultivations. Although areca yellow leaf disease (AYLD) was not previously reported in Sri Lanka, it is a serious disease in neighboring India, reducing yield by much as 50% (Manimekalai et al. 2010). After an occurrence of Weligama coconut leaf wilt disease (WCLWD) in the southern province of Sri Lanka (Perera et al. 2012), areca palms with similar symptoms were noted in the vicinity of the WCLWD-affected plantations. Foliar yellowing of areca palms, the most conspicuous symptom, began from the inner whorl and spread to the outer parts of the crown. Chlorosis was observed on almost all leaves in the whorl. The association of a phytoplasma strain with this yellowing disease was investigated by molecular characterization based on the secA gene in conjunction with scanning electron microscopy (SEM). Symptomatic palms were selected from the vicinity of WCLWD-affected plantations in the Matara District. Symptomless, apparently healthy areca palms were selected from the Kandy District of the central province of the island. Total DNA was extracted from midrib of areca pinnae using the small scale DNA extraction method (Zhang et al. 1998). Total DNA derived from symptomatic and apparently healthy leaf samples were analyzed by primary PCR using a phytoplasma-specific universal primer pair, SecAfor1/SecArev3 (Hodgetts et al. 2008) in the primary PCR, and a 1/10 dilution of this amplicon used as the template to perform the nested PCR using RicesecAfor2/RiceseAcrev3 primers specific for phytoplasma of the 16SrXI and 16SrXIV groups (Bekele et al. 2011). Twelve of 15 symptomatic samples yielded an amplicon of 420 bp; no amplicon was generated by DNA templates from symptomless plants (n = 15). Analysis of these partial secA sequences (NCBI Accession No. KM978910) of this characteristic band of AYLD confirmed the association of a phytoplasma strain that shared 99% nucleotide homology with that of ‘Candidatus Phytoplasma cynodontis’ reference strain and 100% identity with WCLWD phytoplasma (NCBI Accession No. KM978909). Observations of transverse sections of midribs of pinnae of infected spear leaves by SEM revealed the presence of spherical, pleomorphic phytoplasma bodies ranging in diameter from 100 to 1000 nm. These appeared as separate or clustered particles, adhering to the inner surface of sieve tubes of diseased plants. The uneven distribution of phytoplasma bodies in sieve tubes as well as a developmental stage of the phytoplasma (i.e., those undergoing budding) was observed. Phytoplasma bodies were categorically absent in transverse sections of midrib of pinnae of healthy areca leaf samples. To our knowledge, this is the first report of AYLD in Sri Lanka as well as the detection of a 16SrXIV group phytoplasma strain associated with this disease. It is plausible that the same phytoplasma strain is associated with both AYLD and WCLWD. Thus, identification of areca palm as an alternative host of WCLWD phytoplasma will not only increase the complexity of the epidemiology of this disease, but will be more important in implementing control strategies for WCLWD.

Identification of putative odorant binding protein genes in Asecodes hispinarum, a parasitoid of coconut leaf beetle (Brontispa longissima) by antennal RNA-Seq analysis

Asecodes hispinarum (Hymenoptera: Eulophidae) is an endoparasitoid and an efficient biological control agent which attacks larvae of Brontispa longissima, a serious insect pest of Palmae plants in China. Odorant binding proteins (OBPs) are believed to be important for transporting semiochemicals through the aqueous sensillar lymph to the olfactory receptor cells within the insect antennal sensilla. No previous study has reported on OBPs in A. hispinarum. In this study, we conducted the large-scale identification of OBP genes from the antennae of A. hispinarum by using transcriptome sequencing. Approximately 28.4 million total raw reads and about 27.3 million total clean reads were obtained, and then 46,363 unigenes were assembled. Of these unigenes, a total of 21,263 can be annotated in the NCBI non-redundant database. Among the annotated unigenes, 16,623 of them can be assigned to GO (Gene Ontology). Furthermore, we identified 8 putative OBP genes, and a phylogenetic tree analysis was performed to characterize the 8 OBP genes. In addition, the expression of the 8 OBP genes in different A. hispinarum body tissues was analyzed by real-time quantitative polymerase chain reaction (qRT-PCR). The results indicated that the 8 OBP genes were expressed accordingly to sexes and tissues, but all highly expressed in antennae. The finding of this study will lay the foundation for unraveling molecular mechanisms of A. hispinarum chemoperception.

Fourier Transform Infra-Red Spectroscopy and Chemical Resistance of Untreated and Alkali Treated Coconut Leaf Sheath Fiber Reinforced Polymer Composites

In these days, natural fiber and its composites are gaining more interest and utilization of biofibers has increased because of growing concern towards economic, environmental and conservation issues. The present study investigates, Fourier Transform Infra-red (FTIR) spectroscopy and chemical resistance properties on the coconut leaf sheath (CLS) reinforced Phenol Formaldehyde (PF) composites. Naturally woven coconut leaf sheath composites were prepared in both NaOH treated and untreated forms with volume fraction of 60% of sheath and 40% of Phenol Formaldehyde resin. CLS were chemically treated using 5% of NaOH and composite boards were made using a hydraulic hot press at 140°C. FTIR test was conducted for both treated and untreated CLS fiber composites. And it was found that, due to chemical treatment of fibers reduction in lignin and hemicellulose content was observed. The chemical resistance of alkali treated and untreated CLS composites were measured by chemical absorption and chemical thickness swelling methods. Treated and untreated composite samples were then placed in 1N of saline, Hcl, HNO3 and H2SO4 separately. It is also observed that, saline and Hcl have been absorbed more in case of untreated composites and HNO3and H2SO4 is absorbed more in treated composites. These tests were done to know that, these composites can be used in manufacturing products which gives better chemical resistance.