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Lucy N Moleleki - One of the best experts on this subject based on the ideXlab platform.
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the threat of root knot nematodes Meloidogyne spp in africa a review
Plant Pathology, 2014Co-Authors: Edward Makori Onkendi, G M Kariuki, M Marais, Lucy N MolelekiAbstract:Meloidogyne species pose a significant threat to crop production in Africa due to the losses they cause in a wide range of agricultural crops. The direct and indirect damage caused by various Meloidogyne species results in delayed maturity, toppling, reduced yields and quality of crop produce, high costs of production and therefore loss of income. In addition, emergence of resistance-breaking Meloidogyne species has partly rendered various pest management programmes already in place ineffective, therefore putting food security of the continent at risk. It is likely that more losses may be experienced in the future due to the on-going withdrawal of nematicides. To adequately address the threat of Meloidogyne species in Africa, an accurate assessment and understanding of the species present, genetic diversity, population structure, parasitism mechanisms and how each of these factors contribute to the overall threat posed by Meloidogyne species is important. Thus, the ability to accurately characterize and identify Meloidogyne species is crucial if the threat of Meloidogyne species to crop production in Africa is to be effectively tackled. This review discusses the use of traditional versus molecular-based identification methods of Meloidogyne species and how accurate identification using a polyphasic approach can negate the eminent threat of root knot nematodes in crop production. The potential threat to Africa posed by highly damaging and resistance-breaking populations of ‘emerging’ Meloidogyne species is also examined.
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The threat of root‐knot nematodes (Meloidogyne spp.) in Africa: a review
Plant Pathology, 2014Co-Authors: Edward Makori Onkendi, G M Kariuki, M Marais, Lucy N MolelekiAbstract:Meloidogyne species pose a significant threat to crop production in Africa due to the losses they cause in a wide range of agricultural crops. The direct and indirect damage caused by various Meloidogyne species results in delayed maturity, toppling, reduced yields and quality of crop produce, high costs of production and therefore loss of income. In addition, emergence of resistance-breaking Meloidogyne species has partly rendered various pest management programmes already in place ineffective, therefore putting food security of the continent at risk. It is likely that more losses may be experienced in the future due to the on-going withdrawal of nematicides. To adequately address the threat of Meloidogyne species in Africa, an accurate assessment and understanding of the species present, genetic diversity, population structure, parasitism mechanisms and how each of these factors contribute to the overall threat posed by Meloidogyne species is important. Thus, the ability to accurately characterize and identify Meloidogyne species is crucial if the threat of Meloidogyne species to crop production in Africa is to be effectively tackled. This review discusses the use of traditional versus molecular-based identification methods of Meloidogyne species and how accurate identification using a polyphasic approach can negate the eminent threat of root knot nematodes in crop production. The potential threat to Africa posed by highly damaging and resistance-breaking populations of ‘emerging’ Meloidogyne species is also examined.
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Detection of Meloidogyne enterolobii in potatoes in South Africa and phylogenetic analysis based on intergenic region and the mitochondrial DNA sequences
European Journal of Plant Pathology, 2013Co-Authors: Edward M. Onkendi, Lucy N MolelekiAbstract:Root-knot nematodes ( Meloidogyne spp.) are a major problem facing crop production globally including potatoes. During the 2011/2012 potato growing season, root-knot nematode infected potato tubers were obtained from different potato growing regions in South Africa for identification of Meloidogyne spp. Using the intergenic region of the ribosomal DNA (IGS-rDNA) together with the region between the cytochrome oxidase small subunit II (COII) and the 16S rRNA gene in the mitochondrial DNA (mtDNA), five of the 78 composite samples received produced amplicon sizes of 705 bp for COII and 780 bp for IGS typical of M. enterolobii . These five samples were from the KwaZulu-Natal potato producing region. Nucleotide sequencing and phylogenetic analysis of the COII and IGS fragment showed that the five Meloidogyne populations were 100 % similar and they clustered closely with those of M. enterolobii in the GenBank database. The high damage potential of resistance-breaking populations of Meloidogyne species is a threat to profitable potato production and will require effective pest management programmes to be put in place.
Pablo Castillo - One of the best experts on this subject based on the ideXlab platform.
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First report of cultivated Cretan mountain tea (Sideritis syriaca) as a host of Meloidogyne hapla and M. javanica in Crete, with some additional records on the occurrence of Meloidogyne species in Greece.
Journal of Nematology, 2019Co-Authors: Emmanuel A. Tzortzakakis, Carolina Cantalapiedra-navarrete, Antonio Archidona-yuste, Maria Kormpi, Juan E. Palomares-rius, Pablo CastilloAbstract:: Cultivated Cretan mountain tea or Malotira (Sideritis syriaca L.) was found to be infected by Meloidogyne hapla and Meloidogyne javanica in the island of Crete. The authors provide the first molecular characterization of M. hapla in Greece and the first report of Cretan mountain tea or Malotira as a host of Meloidogyne species worldwide. In addition, Meloidogyne hispanica was found infecting aloe (Andros island) and corn (Drama, North Greece) consisting the first reports of natural infection of these plants by M. hispanica in Europe. Furthermore, infection of corn by M. incognita and soybean by M. javanica (Drama, North Greece) are reported for the first time in Greece. Integrative taxonomical approach based on perineal pattern and EP/st ratio, as well as the region of the mitochondrial genome between the cytochrome oxidase subunit II (coxII) and 16S rRNA mitochondrial DNA (mtDNA) genes was used to differentiate Meloidogyne species. : Cultivated Cretan mountain tea or Malotira (Sideritis syriaca L.) was found to be infected by Meloidogyne hapla and Meloidogyne javanica in the island of Crete. The authors provide the first molecular characterization of M. hapla in Greece and the first report of Cretan mountain tea or Malotira as a host of Meloidogyne species worldwide. In addition, Meloidogyne hispanica was found infecting aloe (Andros island) and corn (Drama, North Greece) consisting the first reports of natural infection of these plants by M. hispanica in Europe. Furthermore, infection of corn by M. incognita and soybean by M. javanica (Drama, North Greece) are reported for the first time in Greece. Integrative taxonomical approach based on perineal pattern and EP/st ratio, as well as the region of the mitochondrial genome between the cytochrome oxidase subunit II (coxII) and 16S rRNA mitochondrial DNA (mtDNA) genes was used to differentiate Meloidogyne species.
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Molecular Characterization of Meloidogyne hispanica (Nematoda, Meloidogynidae) by Phylogenetic Analysis of Genes Within the rDNA in Meloidogyne spp.
Plant Disease, 2008Co-Authors: Blanca B Landa, I. M. De O. Abrantes, Nicola Vovlas, Regina M. D. G. Carneiro, Juan E. Palomares Rius, Carla Maleita, Pablo CastilloAbstract:Landa, B. B., Palomares Rius, J. E., Vovlas, N., Carneiro, R. M. D. G., Maleita, C. M. N., Abrantes, I. M. de O., and Castillo, P. 2008. Molecular characterization of Meloidogyne hispanica (Nematoda, Meloidogynidae) by phylogenetic analysis of genes within the rDNA in Meloidogyne spp. Plant Dis. 92:1104-1110. In the past, the distribution of Meloidogyne hispanica, the Seville root-knot nematode, appeared to be restricted to the southern part of Spain and Prunus spp.; however, its distribution has been confirmed to be worldwide because it occurs in all continents (Europe, Africa, Asia, Australia, and North, Central, and South America). Differentiation of M. hispanica from other Meloidogyne spp., mainly M. arenaria, can be very difficult using morphological and biological traits data. These species are quite similar and can be regularly confused in inaccurate taxonomic comparisons. In this study, species-specific polymerase chain reaction (PCR) and phylogenetic analysis of sequences from three ribosomal (r)DNA regions (18S, internal transcribed spacer [ITS]1-5.8S-ITS2, and D2-D3 of 28S) were used to characterize three M. hispanica isolates from different geographical origins (Brazil, Portugal, and Spain). Molecular analyses showed identical sequences for all three isolates for the three rDNA regions. Maximum parsimony analysis of the three rDNA regions and the species-specific PCR demonstrated and supported the differentiation of M. hispanica from M. incognita, M. javanica, and M. arenaria and from all described root-knot nematode species.
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plant parasitic nematodes infecting grapevine in southern spain and susceptible reaction to root knot nematodes of rootstocks reported as moderately resistant
Plant Disease, 2007Co-Authors: Daniel Teliz, Blanca B Landa, Hava F Rapoport, Fernando Perez Camacho, Rafael M Jimenezdiaz, Pablo CastilloAbstract:ABSTRACT Incidence and nematode population densities of plant-parasitic nematodes were determined in 64 samples of soil and grapevine roots collected from commercial vineyards in southern Spain between October 2003 and May 2005. In addition, a histopathological study was done of root-stock roots naturally infected by root-knot nematodes (Meloidogyne spp.). Nematodes infecting the rootstocks were identified according to conventional procedures, and the Meloidogyne spp. were furthermore identified by sequence characterized amplified region-polymerase chain reaction (SCAR-PCR) and isozyme esterase analyses. The most important plant-parasitic nematodes detected, in order of decreasing frequency of total soil infestation and root infection (percentage of samples), were Mesocriconema xenoplax (34.4%), Meloidogyne incognita (26.6%), Meloidogyne javanica (14.1%), Xiphinema index (12.5%), Xiphinema italiae (10.9%), Pratylenchus vulnus (6.3%), and Meloidogyne arenaria (1.6%). No disease symptoms were observed on ab...
Philippe Castagnonesereno - One of the best experts on this subject based on the ideXlab platform.
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hybridization and polyploidy enable genomic plasticity without sex in the most devastating plant parasitic nematodes
PLOS Genetics, 2017Co-Authors: Laetitia Perfusbarbeoch, Romain Blancmathieu, Jeanmarc Aury, Martine Da Rocha, Jerome Gouzy, Erika Sallet, Cristina Martinjimenez, Marc Baillybechet, Philippe CastagnoneserenoAbstract:Root-knot nematodes (genus Meloidogyne) exhibit a diversity of reproductive modes ranging from obligatory sexual to fully asexual reproduction. Intriguingly, the most widespread and devastating species to global agriculture are those that reproduce asexually, without meiosis. To disentangle this surprising parasitic success despite the absence of sex and genetic exchanges, we have sequenced and assembled the genomes of three obligatory ameiotic and asexual Meloidogyne. We have compared them to those of relatives able to perform meiosis and sexual reproduction. We show that the genomes of ameiotic asexual Meloidogyne are large, polyploid and made of duplicated regions with a high within-species average nucleotide divergence of ~8%. Phylogenomic analysis of the genes present in these duplicated regions suggests that they originated from multiple hybridization events and are thus homoeologs. We found that up to 22% of homoeologous gene pairs were under positive selection and these genes covered a wide spectrum of predicted functional categories. To biologically assess functional divergence, we compared expression patterns of homoeologous gene pairs across developmental life stages using an RNAseq approach in the most economically important asexually-reproducing nematode. We showed that >60% of homoeologous gene pairs display diverged expression patterns. These results suggest a substantial functional impact of the genome structure. Contrasting with high within-species nuclear genome divergence, mitochondrial genome divergence between the three ameiotic asexuals was very low, signifying that these putative hybrids share a recent common maternal ancestor. Transposable elements (TE) cover a ~1.7 times higher proportion of the genomes of the ameiotic asexual Meloidogyne compared to the sexual relative and might also participate in their plasticity. The intriguing parasitic success of asexually-reproducing Meloidogyne species could be partly explained by their TE-rich composite genomes, resulting from allopolyploidization events, and promoting plasticity and functional divergence between gene copies in the absence of sex and meiosis.
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diversity and evolution of root knot nematodes genus Meloidogyne new insights from the genomic era
Annual Review of Phytopathology, 2013Co-Authors: Philippe Castagnonesereno, Etienne G J Danchin, Laetitia Perfusbarbeoch, Pierre AbadAbstract:Root-knot nematodes (RKNs) (Meloidogyne spp.) are obligate endoparasites of major worldwide economic importance. They exhibit a wide continuum of variation in their reproductive strategies, ranging from amphimixis to obligatory mitotic parthenogenesis. Molecular phylogenetic studies have highlighted divergence between mitotic and meiotic parthenogenetic RKN species and probable interspecific hybridization as critical steps in their speciation and diversification process. The recent completion of the genomes of two RKNs, Meloidogyne hapla and Meloidogyne incognita, that exhibit striking differences in their mode of reproduction (with and without sex, respectively), their geographic distribution, and their host range has opened the way for deciphering the evolutionary significance of (a)sexual reproduction in these parasites. Accumulating evidence suggests that whole-genome duplication (in M. incognita) and horizontal gene transfers (HGTs) represent major forces that have shaped the genome of current RKN species and may account for the extreme adaptive capacities and parasitic success of these nematodes.
Edward Makori Onkendi - One of the best experts on this subject based on the ideXlab platform.
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the threat of root knot nematodes Meloidogyne spp in africa a review
Plant Pathology, 2014Co-Authors: Edward Makori Onkendi, G M Kariuki, M Marais, Lucy N MolelekiAbstract:Meloidogyne species pose a significant threat to crop production in Africa due to the losses they cause in a wide range of agricultural crops. The direct and indirect damage caused by various Meloidogyne species results in delayed maturity, toppling, reduced yields and quality of crop produce, high costs of production and therefore loss of income. In addition, emergence of resistance-breaking Meloidogyne species has partly rendered various pest management programmes already in place ineffective, therefore putting food security of the continent at risk. It is likely that more losses may be experienced in the future due to the on-going withdrawal of nematicides. To adequately address the threat of Meloidogyne species in Africa, an accurate assessment and understanding of the species present, genetic diversity, population structure, parasitism mechanisms and how each of these factors contribute to the overall threat posed by Meloidogyne species is important. Thus, the ability to accurately characterize and identify Meloidogyne species is crucial if the threat of Meloidogyne species to crop production in Africa is to be effectively tackled. This review discusses the use of traditional versus molecular-based identification methods of Meloidogyne species and how accurate identification using a polyphasic approach can negate the eminent threat of root knot nematodes in crop production. The potential threat to Africa posed by highly damaging and resistance-breaking populations of ‘emerging’ Meloidogyne species is also examined.
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The threat of root‐knot nematodes (Meloidogyne spp.) in Africa: a review
Plant Pathology, 2014Co-Authors: Edward Makori Onkendi, G M Kariuki, M Marais, Lucy N MolelekiAbstract:Meloidogyne species pose a significant threat to crop production in Africa due to the losses they cause in a wide range of agricultural crops. The direct and indirect damage caused by various Meloidogyne species results in delayed maturity, toppling, reduced yields and quality of crop produce, high costs of production and therefore loss of income. In addition, emergence of resistance-breaking Meloidogyne species has partly rendered various pest management programmes already in place ineffective, therefore putting food security of the continent at risk. It is likely that more losses may be experienced in the future due to the on-going withdrawal of nematicides. To adequately address the threat of Meloidogyne species in Africa, an accurate assessment and understanding of the species present, genetic diversity, population structure, parasitism mechanisms and how each of these factors contribute to the overall threat posed by Meloidogyne species is important. Thus, the ability to accurately characterize and identify Meloidogyne species is crucial if the threat of Meloidogyne species to crop production in Africa is to be effectively tackled. This review discusses the use of traditional versus molecular-based identification methods of Meloidogyne species and how accurate identification using a polyphasic approach can negate the eminent threat of root knot nematodes in crop production. The potential threat to Africa posed by highly damaging and resistance-breaking populations of ‘emerging’ Meloidogyne species is also examined.
Jinling Liao - One of the best experts on this subject based on the ideXlab platform.
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a novel effector protein mj nulg1a targeted to giant cell nuclei plays a role in Meloidogyne javanica parasitism
Molecular Plant-microbe Interactions, 2013Co-Authors: Kan Zhuo, Ping Wu, Lianhui Zhang, Jinling LiaoAbstract:Secretory effector proteins expressed within the esophageal glands of root-knot nematodes (Meloidogyne spp.) are thought to play key roles in nematode invasion of host roots and in formation of feeding sites necessary for nematodes to complete their life cycle. In this study, a novel effector protein gene designated as Mj-nulg1a, which is expressed specifically within the dorsal gland of Meloidogyne javanica, was isolated through suppression subtractive hybridization. Southern blotting and BLAST search analyses showed that Mj-nulg1a is unique for Meloidogyne spp. A real-time reverse-transcriptase polymerase chain reaction assay showed that expression of Mj-nulg1a was upregulated in parasitic second-stage juveniles and declined in later parasitic stages. MJ-NULG1a contains two putative nuclear localization signals and, consistently, in planta immunolocalization analysis showed that MJ-NULG1a was localized in the nuclei of giant cells during nematode parasitism. In planta RNA interference targeting Mj-nulg1...
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multiplex pcr for the simultaneous identification and detection of Meloidogyne incognita m enterolobii and m javanica using dna extracted directly from individual galls
Phytopathology, 2011Co-Authors: M X Hu, Kan Zhuo, Jinling LiaoAbstract:Hu, M. X., Zhuo, K., and Liao, J. L. 2011. Multiplex PCR for the simultaneous identification and detection of Meloidogyne incognita, M. enterolobii, and M. javanica using DNA extracted directly from individual galls. Phytopathology 101:1270-1277. Meloidogyne incognita, M. enterolobii, and M. javanica are the most widespread species of root-knot nematodes in South China, affecting many economically important crops, ornamental plants, and fruit trees. In this study, one pair of Meloidogyne universal primers was designed and three pairs of species-specific primers were employed successfully to rapidly detect and identify M. incognita, M. enterolobii, and M. javanica by multiplex polymerase chain reaction (PCR) using DNA extracted from individual galls. Multiplex PCR from all M. incognita, M. enterolobii, and M. javanica isolates generated two fragments of ≈500 and 1,000, 500 and 200, and 500 and 700 bp, respectively. The 500-bp fragment is the internal positive control fragment of rDNA 28S D2/D3 resulting from the use of the universal primers. Other Meloidogyne spp. included in this study generated only one fragment of ≈500 bp in size. Using this approach, M. incognita, M. enterolobii, and M. javanica were identified and detected using DNA extracted directly from individual galls containing the Meloidogyne spp. at various stages of their life cycle. Moreover, the percentage of positive PCR amplification increased with nematode development and detection was usually easy after the late stage of the second-stage juvenile. The protocol was applied to galls from naturally infested roots and the results were found to be fast, sensitive, robust, and accurate. This present study is the first to provide a definitive diagnostic tool for M. incognita, M. enterolobii, and M. javanica using DNA extracted directly from individual galls using a one-step multiplex PCR technique.