DNA PROBES FOR DETECTION OF MYCOPLASMALIKE ORGANISMS ASSOCIATED WITH LETHAL YELLOWING DISEASE OF PALMS IN FLORIDA

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 [P-32]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. At moderate stringency, all probes hybridized with DNA of other MLOs that occur in Florida, and three probes also hybridized to DNA of several Acholeplasma and/or Spiroplasma species. In addition to Manila palms, probes detected the presence of LY MLO DNA in DNA samples extracted from heart tissues of LY-diseased true date (Phoenix dactylifera), cliff date (P. rupicola), Chinese fan (Livistona chinensis), and five coconut (Cocos nucifera) palm cultivars. Probes also hybridized to DNA from symptomatic Caryota rumphiana and L rotundifolia, two palm species previously not known to be affected by LY disease.