Studies on witches' broom of Ligustrum ovalifolium Hasskarl caused by mycoplasma-like organism (MLO)

The occurrence of witches` broom in Ligustrum ovalifolium was first noticed in Korea by auther in 1084. The present study was carried out with particular emphasis on the symptomatology, etiology, transmission of the disease and antibiotic treatments. The infected tissue was observed by the fluorescene and electron microscopy and its biochemical characteristics were compared with healthy one by electrophoresis. The results are summarized as follows : 1. Symptoms of the infected trees were characterized by the dwarfing of the organs, yellowing and brooming of the foliage. 2. The observation by the trans-electron microscopy on the witches` broom of L. ovalifolium revealed the occurrence of numerous myoplasma-like organisms(MLOs) in the phloem tissue cells of the mid ribs of infected leaves. 3. The MLOs were surrounded by a single unit membrane, and they appeared to be multiplied by binary fission. 4. The presence of crystals unidentified in the phloem parenchyma cells was noticed b5 electron microscopy. 5. The disease was able to be transmitted by budding, crown, and greenwood graftings to L. ovalifolium, L. obtusifolium, L. japonicum and also transmitted, even when the stocks and scions were nut completely grafted. 6. Insect transmission on L. ovalifolium and L. obtusifolium was carried by Hishimonus sellatus. 7. The infected roots dipped in the 1,000 ppm of teracyclin solution was only temporarily effective in controlling the disease. 8. Infected plant with MLOs showed specific fluorescent reactions in phloems with DAPI stain. 9 The protein and peroxidase separated by electrophoresis showed strikingly distinctive difference between the healthy and diseased leaves.