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Michel Dollet - One of the best experts on this subject based on the ideXlab platform.
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Spatial distribution of the different strains of the distinct coconut Lethal Yellowing-type phytoplasma species associated with the syndrome in Tanzania
Tropical Plant Pathology, 2021Co-Authors: Anatolia Mpunami, Sandrine Fabre, Fabian Pilet, Allois Kullaya, Matthew Dickinson, Michel DolletAbstract:Phytoplasmas are associated with the Lethal disease of coconut palms in Tanzania (LDT). It is a destructive Lethal Yellowing-type syndrome (LYTS) exhibiting differences in losses between the southern districts and the northern districts. To explain these differences, the existence of variable pathogenic strains of the LDT phytoplasma was investigated using ribosomal RNA gene PCR primers. A total of 84 samples were collected from 67 palms in 14 coastal districts of Tanzania, including the low, moderate, and high incidence areas. Of these, 38 samples were studied in detail. Detected phytoplasma rDNA was characterized by either sequencing of the PCR products and/or restriction fragment length polymorphism (RFLP). Sequence analysis of the P1/P7-primed PCR products revealed several positions of variability, making it possible to distinguish two main geographical clusters. The northern cluster included samples from Tanga region only and is associated with low/moderate disease incidence. A second larger cluster included samples from the rest of the coastline between Bagamoyo and Mtwara. Five genotypes could be identified based on mutations/deletions in the P1/P7 PCR product, two within the northern cluster, and three within the southern cluster. The geographical distribution of the two clusters and the genotypes could be related to the history of coconut introductions in Tanzania. The sequences obtained also confirm that the phytoplasmas associated with LDT are significantly different from all of the other phytoplasmas associated with coconut Lethal Yellowing-type syndromes worldwide, and it is proposed that these phytoplasmas should be classified into their own 16Sr group.
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AGRONOMIE – ENVIRONNEMENT Study on the transmission of coconut Lethal Yellowing in Ghana
2016Co-Authors: Rene Philippe, Sandrine Fabre, Fabian Pilet, Simon Reignard, Sophie Descamps, Joe Nkansah-poku, Robert Quaicoe, Michel DolletAbstract:were applied: shading, daily collections and releasing of insects at the less hot hours and use of various sizes of cages and test plants. More than 70,000 Myndus. adiopodoumeensis were introduced in cage for 28 months (520 adults/seedling/month). Controls in polymerase chain reaction (PCR) on the five coconut of this Myndus cage and on 935 adults were always negative. The tests of transmission with M. adiopodoumeensis apparently not a vector of the disease were thus stopped. The phytoplasma of the CSPWD was identified by PCR in a coconut having received 4,380 Diostrombus (four species of Derbidae) 4 months after the beginning of the test. This coconut never presented symptom of the dis-ease 28 months later and all the successive PCR were negative. Auchenorrhyncha collected by sweeping on the adventitious plants in and around the plot during the day were also tested without success. The hypothesis of a ground transmission was also taken into account because of the presence of scale in-sects and nematodes. Key words: Lethal Yellowing, vector, Homoptera, Auchenorrhyncha, scale insects, coconut, Ghana Phytoplasmas are known to be associated with coconut Lethal Yellowing (LY). It is also known that all phytoplasma diseases are transmitte
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Phytoplasmas identical to coconut Lethal Yellowing phytoplasmas from Zambesia (Mozambique) found in a pentatomide bug in Cabo Delgado province.
Bulletin of Insectology, 2011Co-Authors: Michel Dollet, Feliza Macome, Antonia Vaz, Sandrine FabreAbstract:Phytoplasmas are associated with several syndromes of Lethal Yellowing type of coconut. Only in Florida the insect vector of the local coconut Lethal yellows was identified to be Myndus crudus (Cixiidae). In Mozambique, phytoplasmas are associated with a coconut Lethal Yellowing type syndrome. In the Cabo Delagdo province, some pentatomids of the species Platacantha lutea were found carrying the same phytoplasmas as those identified in the diseased coconut on which they were found. As some pentatomids are vectors of other phloem-restricted pathogens associated with a coconut Lethal Yellowing type syndrome, hypothesis of a possible pentatomid as a vector is proposed. (Resume d'auteur)
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Review of Coconut “Lethal Yellowing” type diseases Diversity, variability and diagnosis
Oléagineux Corps gras Lipides, 2009Co-Authors: Michel Dollet, Robert N Quaicoe, Fabian PiletAbstract:Coconut palms (Cocos nucifera L.) can be affected by several types of Lethal Yellowing (LY) diseases worldwide. Some of the syndromes are caused by phytoplasmas, small bacteria that are impossible to detect by light microscopy. Amplification of a given gene of the phytoplasmas by polymerase chain reaction (PCR) is the most convenient diagnosis method. The problem is that there are at least 28 “groups” of phytoplasmas and only one pair of primers -P1/P7- commonly used for PCR. As these primers belong to a very conserved gene, false positives are frequent. Consequently, alternative primers specific to one “strain” (or subgroup) have to be used, such as LY-F/LY-R for the Caribbean LY, Rohde primers for LD Tanzania. Such specific primers are sometimes restrictive. Indeed, there is variability within each strain and the sequence of the primers has to be adapted to that variability. There are at least five LY subgroups. The subgroups can only be identified by restriction fragment length polymorphism or sequencing. In Africa, two subgroups of LY phytoplasmas have been identified so far.
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General overview of genetic research and experimentation on coconut varieties tolerant/resistant to Lethal Yellowing
Oléagineux Corps gras Lipides, 2009Co-Authors: Luc Baudouin, Robert N Quaicoe, Rene Philippe, Sylvester Dery, Michel DolletAbstract:The Lethal Yellowing (LY) disease is one of the main threats to coconut industry in many parts of Africa and the Caribbean. Planting resistant varieties has long been recognized as one of the most promising ways of controlling the disease. Considerable efforts have been devoted throughout the world to screening suitable varieties and have often involved international cooperation. It has proven to be a lengthy and difficult task. We present an overview of these efforts with special mention to Ghana, Jamaica and Mexico. Although no variety so far has been proven fully and permanently resistant, treating resistance level as a threshold trait makes it possible to demonstrate significant differences among varieties, which can be exploited effectively to make genetic improvement a component of an integrated control strategy. Based on past experience, we make a few suggestions to increase the diversity of resistance sources and increase the level and the sustainability of resistance to LY in coconut.
Carlos Oropeza - One of the best experts on this subject based on the ideXlab platform.
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Distribution of Lethal Yellowing and associated phytoplasma strains in Jamaica, Mexico and other countries in the region
Phytopathogenic Mollicutes, 2019Co-Authors: Wayne Myrie, Maria Narvaez, Carlos F. Ortiz, Carlos OropezaAbstract:The relentless spread of the fatal disease Lethal Yellowing (LY) throughout the coconut growing areas is having a serious impact on many vulnerable communities. Phytoplasmas from the 16SrIV group are the associated agents. These obligated phytopathogenic mollicutes systemically colonize phloem tissues inducing numerous biochemical and physiological changes leading to symptom development and ultimate death of coconut palms. Large numbers of coconut trees succumbed to the disease over the past three decades. There are different subgroups of the 16SrIV phytoplasmas affecting palms in the Americas. It is important for these to be properly identified along with the epidemiology of the disease. The effective molecular tools used to identify these subgroups show variations in some conserved genomic regions. In the Americas the subgroups have been identified, the current distribution of LY in Jamaica and Mexico and the 16SrIV subgroups occurring in these countries and in other Caribbean countries are described.
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Changes observed in Pritchardia pacifica palms affected by a Lethal Yellowing-type disease in Mexico
African Journal of Biotechnology, 2017Co-Authors: Mar Ia Narv Aez, Carmen Silverio, Francisco Espadas, Carlos OropezaAbstract:Lethal Yellowing (LY) is a devastating disease, affecting more than 35 palm species. One of them, Pritchardia pacifica, was found to be very susceptible in Florida and it is affected by a LY-type syndrome in Yucatan, Mexico. In this study, plants of P. pacifica were exposed naturally to feral insects in an area affected by LY in Mexico. All the plants exposed died showing symptoms of leaf decay with death occurring within approximately four months after first symptom. Real-time (polymerase chain reaction) PCR analysis of DNA extracts for phytoplasma detection and in silico sequence analysis of nested-PCR amplicons showed an association with 16SrIV-D phytoplasmas in plants studied. Time-course changes were studied for the detection of phytoplasmas, stomatal conductance and leaf temperature by thermography. One month before appearance of the first symptom, changes in all the parameters were observed: positive detection of phytoplasma DNA, a reduction in stomatal conductance that is complete and irreversible, and the appearance of a peak in leaf temperature. These results provide insights into a better understanding of this disease in P. pacifica. Moreover, from a practical point of view, the changes described could be useful for developing methods for early detection of the disease. Key words: Lethal Yellowing-type disease, phytoplasmas, Pritchardia pacifica, stomatal conductance, thermography.
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Detection and identification of Lethal Yellowing phytoplasma 16SrIV-A and D associated with Adonidia merrillii palms in Mexico
Australasian Plant Pathology, 2017Co-Authors: Iván Cordova Lara, Carlos Oropeza, Luis Mota Narváez, Luis SáenzAbstract:Adonidia merrillii is a palm species native to the Philippines and commonly known as the manila palm. Lethal Yellowing-type symptoms were first observed for the manila palm in Florida, USA. Manila palms in Mexico have not been reported to carry the Lethal Yellowing-type phytoplasma and moreover we have documented other symptoms that are not commonly associated to Lethal Yellowing (LY) disease. Therefore, our objective was to use molecular techniques to identify and characterize the presence of phytoplasmas in manila palms from southeastern Mexico. Thirty-three manila palm plants were analyzed. In general, three syndromes were observed: mature leaf browning, spear leaf necrosis and spear leaf opening. The presence of phytoplasma DNA was detected by nested-PCR using universal and LY-specific primers. Of the 33 palms analyzed, 24 (73%) were positive for the presence of phytoplasmas using universal primers, and 18 (55%) were positive for phytoplasma DNA using the LY-specific primers. By a TaqMan/real-time PCR assay for LY detection, 82% of palms tested were positive for LY-specific phytoplasma DNA. The restriction enzyme profiles of the DNA tested showed two clear patterns. One pattern was similar to that of the phytoplasma 16SrIV-A strain associated with coconut LY, and the other corresponded to the Pritchardia pacifica 16SrIV-D strain. The 16SrIV-A strain is associated with mature leaf-browning syndrome. The palms infected with the 16Sr-IV-D phytoplasma exhibited spear leaf necrosis and opening. This is the first report of two phytoplasma strains belonging to the subgroups 16SrIV-A and 16SrIV-D in manila palms.
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phytoplasma distribution in coconut palms affected by Lethal Yellowing disease
Annals of Applied Biology, 2011Co-Authors: Carlos Oropeza, Ivan Cordova, Luis Sáenz, Maria Narvaez, A Chumba, R Ashburner, N A HarrisonAbstract:Lethal Yellowing (LY), the most devastating disease affecting the coconut palm in America, is caused by phytoplasmas known to be distributed in different parts of infected plants. However, no comprehensive reports exist on the phytoplasma distribution. This study refers to the detection of LY phytoplasma DNA using PCR in different coconut plant parts, throughout the development of the disease. Sample analysis of positive palms taken at different stages of disease development (either symptomatic or symptomless) showed differences in the percentage of LY detection between plant parts. Some parts showed a very high level of LY DNA (stem, young leaves, inflorescences, stem apex and root apex), low levels were found in the intermediate leaves and roots without apex, whereas no LY phytoplasma DNA was detected in mature leaves. The detection percentage of LY phytoplasma DNA was lowest in symptomless-infected palms for all parts, except the stem, where phytoplasma accumulations were consistently detected. This pattern of detection among parts is consistent with the hypothesis that phytoplasmas move from photosynthate source tissues to sink tissues via the phloem mass flow process. The accumulations in the (lower) stem, prior to the appearance of symptoms, suggest that this part of the palm is where phytoplasmas first move from leaves after foliar feeding by vectors and in which they probably multiply and distribute to other palm parts, including roots. Embryos from infected palms were analysed by nested-PCR and 28% of 394 embryos were positive. Phytoplasma DNA was detected in embryos from fruit on any of the fruiting bunches regardless the age, but no pattern of quantitative distribution throughout the bunch developmental stages was observed. Germination of seeds from LY-positive symptomatic palms was 58% and from LY-negative symptomless palms were 71%. No phytoplasma was detected in seedlings tested from both symptomatic and non-symptomatic palms. Seedlings tested after 2 years did not develop LY symptoms or eventually died.
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changes in carbohydrate metabolism in coconut palms infected with the Lethal Yellowing phytoplasma
Phytopathology, 2003Co-Authors: B. Maust, M.l. Aguilar, F. Espadas, Jorge M. Santamaría, C Talavera, Carlos OropezaAbstract:ABSTRACT Lethal Yellowing (LY), a disease caused by a phytoplasma, is the most devastating disease affecting coconut (Cocos nucifera) in Mexico. Thousands of coconut palm trees have died on the Yucatan peninsula while plantations in Central America and on the Pacific coast of Mexico are severely threatened. Polymerase chain reaction assays enable identification of incubating palm trees (stage 0+, phytoplasma detected but palm asymptomatic). With the development of LY, palm trees exhibit various visual symptoms such as premature nut fall (stage 1), inflorescence necrosis (stages 2 to 3), leaf chlorosis and senescence (stages 4 to 6), and finally palm death. However, physiological changes occur in the leaves and roots prior to onset of visual symptoms. Stomatal conductance, photosynthesis, and root respiration decreased in stages 0+ to 6. The number of active photosystem II (PSII) reaction centers decreased during stage 2, but maximum quantum use efficiency of PSII remained similar until stage 3 before decl...
N A Harrison - One of the best experts on this subject based on the ideXlab platform.
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Comparison of the ribosomal RNA operon from Texas Phoenix decline and Lethal Yellowing phytoplasmas
European Journal of Plant Pathology, 2012Co-Authors: K. Ntushelo, N A Harrison, M. L. ElliottAbstract:A comparison was made of the two palm yellows phytoplasmas affecting palms to determine if the entire ribosomal RNA operon portion of the phytoplasma genome, or portions thereof, could account for the observed palm host differences. Polymerase chain reaction (PCR) was used to amplify a 5.0 kb DNA fragment consisting of the entire ribosomal RNA operon from a subgroup 16SrIV-D phytoplasma that causes Texas Phoenix palm decline (TPD) in cabbage ( Sabal palmetto ) palm in west central Florida and from a subgroup 16SrIV-A phytoplasma that causes Lethal Yellowing (LY) in coconut ( Cocos nucifera ) palm in Jamaica. Before the PCR reaction, we sequenced by 454 sequencing a draft genome of the coconut LY phytoplasma, strain LYFL, that infects C. nucifera in Florida, and obtained from this draft sequence both copies of the entire ribosomal operon. Sequence analysis of the ribosomal RNA operons from both the LY and TPD phytoplasmas revealed the gene composition and orientation for the operons to be 5′16S rRNA-tRNA^Ile-23S rRNA-5S rRNA3′ and a tRNA^Val3′ downstream of the 5S rRNA gene. Based on molecular comparisons using the sequences of the ribosomal RNA operon, the TPD (16SrIV-D) strain was 98 % similar to the LY (16SrIV-A) strains.
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phytoplasma distribution in coconut palms affected by Lethal Yellowing disease
Annals of Applied Biology, 2011Co-Authors: Carlos Oropeza, Ivan Cordova, Luis Sáenz, Maria Narvaez, A Chumba, R Ashburner, N A HarrisonAbstract:Lethal Yellowing (LY), the most devastating disease affecting the coconut palm in America, is caused by phytoplasmas known to be distributed in different parts of infected plants. However, no comprehensive reports exist on the phytoplasma distribution. This study refers to the detection of LY phytoplasma DNA using PCR in different coconut plant parts, throughout the development of the disease. Sample analysis of positive palms taken at different stages of disease development (either symptomatic or symptomless) showed differences in the percentage of LY detection between plant parts. Some parts showed a very high level of LY DNA (stem, young leaves, inflorescences, stem apex and root apex), low levels were found in the intermediate leaves and roots without apex, whereas no LY phytoplasma DNA was detected in mature leaves. The detection percentage of LY phytoplasma DNA was lowest in symptomless-infected palms for all parts, except the stem, where phytoplasma accumulations were consistently detected. This pattern of detection among parts is consistent with the hypothesis that phytoplasmas move from photosynthate source tissues to sink tissues via the phloem mass flow process. The accumulations in the (lower) stem, prior to the appearance of symptoms, suggest that this part of the palm is where phytoplasmas first move from leaves after foliar feeding by vectors and in which they probably multiply and distribute to other palm parts, including roots. Embryos from infected palms were analysed by nested-PCR and 28% of 394 embryos were positive. Phytoplasma DNA was detected in embryos from fruit on any of the fruiting bunches regardless the age, but no pattern of quantitative distribution throughout the bunch developmental stages was observed. Germination of seeds from LY-positive symptomatic palms was 58% and from LY-negative symptomless palms were 71%. No phytoplasma was detected in seedlings tested from both symptomatic and non-symptomatic palms. Seedlings tested after 2 years did not develop LY symptoms or eventually died.
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detection and characterization of a Lethal Yellowing 16sriv group phytoplasma in canary island date palms affected by Lethal decline in texas
Plant Disease, 2002Co-Authors: N A Harrison, Mary Womack, M L CarpioAbstract:ABSTRACT Polymerase chain reaction (PCR) assays were used to detect phytoplasmas in Canary Island date (Phoenix canariensis) palms displaying symptoms similar to Lethal Yellowing (LY) disease in Corpus Christi, TX. An rDNA product (1.8 kb) was amplified consistently from 10 of 11 palms by PCR employing phytoplasma universal rRNA primer pair P1/P7. Also, AluI endonu-clease digests and sequencing of P1/P7 products revealed that nontarget Bacillus megaterium-related rDNA sequences of similar size were co-amplified along with phytoplasma rDNA from 10 palms. A 1,402-bp product was obtained from all 11 symptomatic palms when initial P1/P7 products were reamplified by PCR employing nested LY phytoplasma group-specific 16S rRNA primer pair LY16Sf/LY16Sr. Restriction fragment length polymorphism (RFLP) analysis of nested PCR products revealed that palm-infecting phytoplasmas were uniform and most similar to strains composing the coconut Lethal Yellowing phytoplasma (16SrIV) group. Sequence analysis of 16S rDNA det...
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detection of the mycoplasma like organism associated with Lethal Yellowing disease of palms in florida by polymerase chain reaction
Plant Pathology, 1994Co-Authors: N A Harrison, P. A. Richardson, J. B. Kramer, J. H. TsaiAbstract:DNA amplification by polymerase chain reaction (PCR) was used specifically to detect the mycoplasma-like organism (MLO) associated with Lethal Yellowing disease of palms in Florida, For PCR, a pair of oligonucleotide primers was synthesized according to partial sequences of a cloned 1-3 kbp fragment of Lethal Yellowing MLO-specific genomic DNA isolated from a diseased windmill palm (Trachycarpusfortunei). A DNA product of about 1 kbp was specifically amplified by PCR in reaction mixtures containing template DNA derived from either heart, inflorescence or leaf tissues of Lethal Yellowing-affected palms. PCR perfonned for 35 cycles with as little as 5 pg of DNA template, in some instances, was sufficient consistently to amplify the same Lethal Yellowing MLO DNA product from hearts of 11 species comprising 30 symptomatic palms. Similar reliable and reproducible detection of the Lethal Yellowing MLO in palm inflorescence spikelets was also achieved after 35 cycles of PCR. When template DNA for PCR was derived from tissues of the the most immature emerging leaf, a 40cycle reaction was suflicient for consistent foliar detection of the pathogen in all coconut palms including palms with earliest visible symptoms of disease.
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DNA probes for detection of mycoplasmalike organisms associated with Lethal Yellowing disease of palms in Florida
Phytopathology, 1992Co-Authors: N A Harrison, J. H. Tsai, C. M. Bourne, R. L. Cox, P. A. RichardsonAbstract:Five EcoRI restriction fragments consisting of chromosomal DNA of the mycoplasmalike organism (MLO) associated with Lethal Yellowing (LY) disease of Manila palm (Veitchia merrillii) in Florida were cloned and identified. When used individually as [ 32 P]dATP-labeled probes in dot and Southern hybridizations at high stringency, four of five probes consistently hybridized to DNA extracts derived from LY-affected palms only (...)
Fabian Pilet - One of the best experts on this subject based on the ideXlab platform.
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Spatial distribution of the different strains of the distinct coconut Lethal Yellowing-type phytoplasma species associated with the syndrome in Tanzania
Tropical Plant Pathology, 2021Co-Authors: Anatolia Mpunami, Sandrine Fabre, Fabian Pilet, Allois Kullaya, Matthew Dickinson, Michel DolletAbstract:Phytoplasmas are associated with the Lethal disease of coconut palms in Tanzania (LDT). It is a destructive Lethal Yellowing-type syndrome (LYTS) exhibiting differences in losses between the southern districts and the northern districts. To explain these differences, the existence of variable pathogenic strains of the LDT phytoplasma was investigated using ribosomal RNA gene PCR primers. A total of 84 samples were collected from 67 palms in 14 coastal districts of Tanzania, including the low, moderate, and high incidence areas. Of these, 38 samples were studied in detail. Detected phytoplasma rDNA was characterized by either sequencing of the PCR products and/or restriction fragment length polymorphism (RFLP). Sequence analysis of the P1/P7-primed PCR products revealed several positions of variability, making it possible to distinguish two main geographical clusters. The northern cluster included samples from Tanga region only and is associated with low/moderate disease incidence. A second larger cluster included samples from the rest of the coastline between Bagamoyo and Mtwara. Five genotypes could be identified based on mutations/deletions in the P1/P7 PCR product, two within the northern cluster, and three within the southern cluster. The geographical distribution of the two clusters and the genotypes could be related to the history of coconut introductions in Tanzania. The sequences obtained also confirm that the phytoplasmas associated with LDT are significantly different from all of the other phytoplasmas associated with coconut Lethal Yellowing-type syndromes worldwide, and it is proposed that these phytoplasmas should be classified into their own 16Sr group.
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AGRONOMIE – ENVIRONNEMENT Study on the transmission of coconut Lethal Yellowing in Ghana
2016Co-Authors: Rene Philippe, Sandrine Fabre, Fabian Pilet, Simon Reignard, Sophie Descamps, Joe Nkansah-poku, Robert Quaicoe, Michel DolletAbstract:were applied: shading, daily collections and releasing of insects at the less hot hours and use of various sizes of cages and test plants. More than 70,000 Myndus. adiopodoumeensis were introduced in cage for 28 months (520 adults/seedling/month). Controls in polymerase chain reaction (PCR) on the five coconut of this Myndus cage and on 935 adults were always negative. The tests of transmission with M. adiopodoumeensis apparently not a vector of the disease were thus stopped. The phytoplasma of the CSPWD was identified by PCR in a coconut having received 4,380 Diostrombus (four species of Derbidae) 4 months after the beginning of the test. This coconut never presented symptom of the dis-ease 28 months later and all the successive PCR were negative. Auchenorrhyncha collected by sweeping on the adventitious plants in and around the plot during the day were also tested without success. The hypothesis of a ground transmission was also taken into account because of the presence of scale in-sects and nematodes. Key words: Lethal Yellowing, vector, Homoptera, Auchenorrhyncha, scale insects, coconut, Ghana Phytoplasmas are known to be associated with coconut Lethal Yellowing (LY). It is also known that all phytoplasma diseases are transmitte
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Large scale management of coconut Lethal Yellowing disease in Mozambique : P14.006
2013Co-Authors: N. Munguambe, R. Timbrine, Marcos Freire, S. Gadaga, Patricia Da Silva Dias, B. Do Rosario, J. Pudivitr, Fabian PiletAbstract:Mozambique was, at the beginning of the 1900's, one of the biggest world copra producers. Since the 1990s the coconut crop became seriously threatened by Coconut Lethal Yellowing Disease (CLYD), an insect transmitted disease caused by phytoplasma, which killed, up to 2008, at least 7,000,000 coconut palms. To support the smallholder coconut sector the MCA-FISP project started in 2009 was designed to reduce the impact of the disease through the use of containment measures consisting on culling and elimination of symptomatic disease trees to reduce its spread. In the early 1980s it was estimated that Nampula and Zambezia Provinces had about 122,000 ha of coconut trees. By 2009, 40,000 ha were destroyed by the disease, with an additional 25,000 ha under heavy disease pressure. Since 2010, the FISP project hired a contractor that culled with chainsaws about 600,000 coconut trees from an area of 50,000 ha belonging to smallholder farmers. The felled palms were selected based on the visual observation CLYD symptoms. The efficiency of the selection system was further confirmed through molecular analysis showing that the level of selection mistakes was within acceptable levels. This activity effectively reduced the average disease incidence from 5% to below 2% based on annual field surveys. Because the FISP project will end by September 2013, manual tree culling by the smallholders was recently started as a strategy for sustainability which is recognized to be a reasonable solution to maintain the disease at acceptable economic levels. (Resume d'auteur)
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Molecular diagnosis of the Coconut Lethal Yellowing Disease in Mozambique : Consultancy report, mission 4 under the contract N° 01/MU/11
2013Co-Authors: Fabian PiletAbstract:The purpose of this fourth appraisal mission on the molecular diagnosis of Lethal Yellowing for the MCA-FISP project was to analyse the results obtained by the Quelimane laboratory since the beginning of the year. The laboratory is perfectly operational. The CLYD molecular diagnosis results obtained by the laboratory appear to be perfectly satisfactory with a very low sample contamination rate. The number of positive samples is low, but that is coherent with the mission of the laboratory. The quantitative objectives remain lower than initially defined due to a shortage of staff. The laboratory could devote a larger share of its activities to establishing a collection of samples representative of CLYD in Mozambique. (Resume d'auteur)
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Review of Coconut “Lethal Yellowing” type diseases Diversity, variability and diagnosis
Oléagineux Corps gras Lipides, 2009Co-Authors: Michel Dollet, Robert N Quaicoe, Fabian PiletAbstract:Coconut palms (Cocos nucifera L.) can be affected by several types of Lethal Yellowing (LY) diseases worldwide. Some of the syndromes are caused by phytoplasmas, small bacteria that are impossible to detect by light microscopy. Amplification of a given gene of the phytoplasmas by polymerase chain reaction (PCR) is the most convenient diagnosis method. The problem is that there are at least 28 “groups” of phytoplasmas and only one pair of primers -P1/P7- commonly used for PCR. As these primers belong to a very conserved gene, false positives are frequent. Consequently, alternative primers specific to one “strain” (or subgroup) have to be used, such as LY-F/LY-R for the Caribbean LY, Rohde primers for LD Tanzania. Such specific primers are sometimes restrictive. Indeed, there is variability within each strain and the sequence of the primers has to be adapted to that variability. There are at least five LY subgroups. The subgroups can only be identified by restriction fragment length polymorphism or sequencing. In Africa, two subgroups of LY phytoplasmas have been identified so far.
Wayne Mclaughlin - One of the best experts on this subject based on the ideXlab platform.
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Identification of Lethal Yellowing group (16SrIV) of phytoplasmas in the weeds Stachytarpheta jamaicensis, macroptilium lathyroides and cleome rutidosperma in Jamaica
Phytopathogenic Mollicutes, 2011Co-Authors: Sherline E. Brown, Wayne MclaughlinAbstract:A survey was conducted to identify weed hosts of the Lethal Yellowing phytoplasma in areas that had high (St Thomas and Portland) as well as low incidences (St Mary and St Elizabeth) of the disease. More than 600 weed samples representing 46 species in 23 families were collected from 30 field sites over a 16 month period. Coconut Lethal Yellowing phytoplasma was detected in samples of the weeds Cleome rutidosperma, Macroptilium lathyroides and Stachytarpheta jamaicensis in all the places tested in Jamaica by nested polymerase chain reaction (PCR) assay employing the 16SrRNA primer pairs P1/P7 and LY16Sf/LY16Sr. A 1,400-bp product was obtained from 21 out of 35 S. jamaicensis, 26 out of 75 C. rutidosperma and 29 out of 89 M. lathyroides weeds analyzed. Restriction fragment length polymorphism (RFLP) analyses of nested PCR products using the enzymes AluI, MspI and Tru9I revealed that there are different RFLP variants of the LY phytoplasma infecting the weeds S. jamaicensis, M. lathyroides and C. rutidosperma. The weed infecting phytoplasma strains could be classified tentatively as members of the Lethal Yellowing (LY) phytoplasma (16SrIV-E) group. All the LY16Sf/LY16Sr sequences from the three weed species were approximately 98% identical to that of the phytoplasma strains in Floridsa (LYFL-C2) and Jamaica (LYJ-C8). The LY phytoplasmas found in the three weeds analyzed clustered together with previously characterized strains within the Lethal Yellowing phytoplasma (16SrIV) group.
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First Report of Lethal Yellowing Group (16Sr IV) of Phytoplasmas in Vernonia cinerea in Jamaica.
Plant disease, 2008Co-Authors: S. E. Brown, B. O. Been, Wayne MclaughlinAbstract:Coconut Lethal Yellowing disease (CLY) has had a devastating effect on the coconut (Cocos nucifera L.) industry in Jamaica and Latin America. A study was conducted in Jamaica during 2005 to identify alternate hosts of the CLY phytoplasma. Since weeds are known to act as reservoir hosts of numerous pathogens, Vernonia cinerea (L.) (Asteraceae), a prevalent weed species on coconut farms island-wide, was collected from coconut farms in areas of high and low levels of CLY incidence, although none of the plants displayed disease symptoms. DNA was extracted from plant samples by the method of Dellaporta et al. (1) and analyzed by nested PCR assay employing phytoplasma universal rRNA operon primers P1/P7 (2,4) and LY16Sf/LY16-23Sr (3). DNA derived from CLY-diseased or healthy coconut palm served as positive and negative controls, respectively, in each assay. Amplification of an rDNA product of the expected size (1.7 kb) confirmed phytoplasma infections in 53 of 118 (44.9%) V. cinerea test plants. Twenty-seven of...
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First Report of Lethal Yellowing Disease of Coconut Palms Caused by Phytoplasma on Nevis Island.
Plant disease, 2006Co-Authors: W.a. Myrie, Basil Been, M. Dollet, Litta P. Paulraj, D. Wray, Wayne MclaughlinAbstract:Coconuts (Cocos nucifera) are an important small-holder's crop in many tropical countries and are used to enhance esthetics of coastal areas. Lethal Yellowing (LY) is the single most important plant disease affecting the coconut industry in Jamaica. It affects many palm species in Jamaica, Florida, and Guatemala. This coconut disease was first recorded in Grand Cayman Island in 1834 and Jamaica in 1884. Symptoms of LY disease include premature nut fall, necrosis of the inflorescence, Yellowing of the leaves, and defoliation. Thirty-eight coconut palms displaying symptoms indicative of LY disease were sampled in April, 2005 at several locations in Nevis. Immature leaf tissues (leaf bases adjacent to the apical meristem) and nondestructive (boring with a bit and braces) samples were collected from disease and healthy control coconut trees. DNA was extracted (2). The first round of polymerase chain reaction (PCR) with phytoplasma universal primer pair P1/P7 (1,3) resulted in an rDNA fragment of 1.8 kb, and a...