Observation by Electron Microscope for Mycoplasma-like Organism in Large Chinese Hawthorn with Witches’ Broom

Large Chinese hawthorn (Crataegus pinnatifida var. major N. E. Br.) witches' broom was found in Beijing in China. Plant-diseased sprouted later, and there was not a distinct internodes on branches. Little leaves were bunchy and yellow. Branches infected withered slowly from the top downwards. Flowers were faded and degenerated, small and deformed. Flower buds can't produce normal fruit-twigs and fruits. White flowers turn pink or purplish red.Transmission electron microscope revealed numerous-spherical and elliptical MLO, in the sieve element of the top or the vein or the pedicel from MLO-infected plants. They were measured, the spherical is 433 nm and elliptical is 480nm×609nm. MLO, havn't been found in healthy plant samples.