Browsing by Author "Jones, P."

Now showing 1 - 6 of 6
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    16S rRNA interoperon sequence heterogeneity distinguishes strain populations of palm lethal yellowing phytoplasma in the Caribbean region
    (2002) Harrison, N.A.; Myrie, W.; Jones, P.; Carpio, M.L.; Castillo, M.; Doyle, M.M.; Oropeza, C.
    DNA of phytoplasmas in lethal yellowing (LY)-diseased palms was detected by a nested polymerase chain reaction (PCR) assay employing rRNA primer pair P1/P7 followed by primer pair LY16Sf/ LY16-23Sr. Polymorphisms revealed by Hinfl endonuclease digestion of rDNA products differentiated coconut-infecting phytoplasmas in Jamaica from those detected in palms in Florida, Honduras and Mexico. A three fragment profile was generated for rDNA from phytoplasmas infecting all 21 Jamaican palms whereas a five fragment profile was evident for phytoplasmas infecting the majority of Florida (20 of 21), Honduran (13 of 14) and Mexican (5 of 5) palms. The RFLP profile indicative of Florida LY phytoplasma was resolved by cloning into two patterns, one of three bands and the other of four bands, that together constituted the five fragment profile. The two patterns were attributed to presence of two sequence heterogeneous rRNA operons, rrnA and rrnB, in most phytoplasmas composing Florida, Honduran and Mexican LY strain populations. Unique three and four fragment RFLP profiles indicative of LY phytoplasmas infecting Howea forsteriana and coconut palm in Florida and Honduras, respectively, were also observed. By comparison, the Jamaican LY phytoplasma population uniformly contained one or possibly two identical rRNA operons. No correlation between rRNA interoperon heterogeneity and strain variation in virulence of the LY agent was evident from this study.
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    Genetic diversity in the coconut lethal yellowing disease phytoplasmas of East Africa
    (1999) Mpunami, A.A.; Tymon, A.; Jones, P.; Dickinson, M.J.
    DNA primers, based on the ribosomal sequences of lethal yellowing-type disease (LYD) phytoplasmas, were used to analyse genetic variation within the lethal yellowing-type diseases of coconut in East Africa. Samples were collected from palms in Kenya, Mozambique and high, medium and low disease incidence areas of Tanzania. The mollicutespecific primer pair P1 and P6 amplified a 1·5 kbp product from all diseased palms and no product from symptomless palms, indicating that phytoplasmas were associated with all of these diseases. However, the Rohde forward and Rohde reverse primers (a second rRNA primer pair designed to detect East African LYD-associated phytoplasmas) only amplified products from Tanzanian and Kenyan diseased palms and not from those of Mozambique. Conversely, primers Ghana 813 and AK-SR, designed for specific detection of coconut-associated phytoplasmas in West Africa, amplified products only from the Mozambique palms, indicating that the phytoplasma associated with LYD in Mozambique is more closely related to those fromWest Africa. This was supported by restriction enzyme digestion of PCR products. DNA sequencing of PCR products from phytoplasmas within Tanzania revealed no detectable differences in the rDNA sequences of isolates from high, medium and low incidence areas.
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    Identification of potential vectors of the coconut lethal disease phytoplasma
    (2000) Mpunami, A.; Tymon, A.; Jones, P.; Dickinson, M.J.
    Lethal disease (LD) is a lethal yellowing-type disease of coconuts associated with phytoplasmas in Tanzania, but the insect vector for it has not yet been identified. In this study, the auchenorrynchous insects in LD-infected coconut fields were surveyed to determine potential vectors for the disease. No significant correlation was found between disease incidence and numbers of insects collected from the field, possibly reflecting the unknown incubation period for the disease. However, analysis of more than 5000 individual insects by the polymerase chain reaction (PCR), using LD-specific primers derived from the phytoplasma 16S rRNA gene, revealed PCR products of the correct size from eight individuals of Diastrombus mkurangai and four of Meenoplus spp. When digested with restriction endonucleases, fragments of the same size as the LD phytoplasma were obtained. No PCR products were detected in any of the other insect species tested. These results implicate D. mkurangai and Meenoplus spp. as probable vectors of the LD phytoplasma.