Browsing by Author "Cordova, I."

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    Phytoplasma distribution in coconut palms affected by lethal yellowing disease
    (2011) Oropeza, C.; Cordova, I.; Chumba, A.; Narvaez, M.; Saenz, L.; Ashburner, R.; Harrison, N.
    Lethal yellowing (LY), the most devastating disease affecting the coconut palm correspondence in America, is caused by phytoplasmas known to be distributed in different Dr C. Oropeza, Biotechnology Unit, Centro de pans of infected plants. However, no comprehensive reports exist on the phytoInvestigaci6n Cientlfica de Yucatan, Calle 43 plasma distribution. This study refers to the detection of LY phytoplasma DNA No. 130. Colonia Chuburna de Hidalgo, 97200 using PCR in different coconut plant pans, throughout the development of the Merida, Yucatan, Mexico. disease. Sample analysis of positive palms taken at different stages of disease Email: cos@cicy.mx development (either symptomatic or symptomless) showed differences in the Received: 19 November 2010; revised version percentage of LY detection between plant parts. Some parts showed a very high accepted: 1 April 2011. 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, dOi:10.11111j.1744-7348.2011.00480.x whereas no LYphytoplasma 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 symntoms, suggest that this pan 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.