Studies on Mycoplasma-Like Organism Associated with Witches' Broom of Rhus javanica (I)

Mycoplasma 성(性) 붉나무빗자루병(病)에 관(關)한 연구(硏究) (I)

The occurrence of witches' broom of Rhus javanica was first noticed in Korea by the author in 1979. Subsequently, studies were made on the symptomatology, etiology, and transmission of the disease, as well as the effect of some antibiotics on the disease development. The results of these studies are summarized as follows: 1. Symptoms of the infected plant were characterized by dwarfing of the tree accompanied by yellowing and brooming of the foliage. 2. Electron microscopy of witches' broom diseased Rhus javanica plant revealed the occurrence of numerous mycoplasma-like organisms (MLO's) in the phloem tissue cells (sieve tube elements and phloem parenchyma cells) of the rachis and midribs of infected leaves. 3. The MLO's were bounded by a single unit membrane and contained ribosome-like granules and strands presumed to be DNA. It also appears that the MLO multiply possibly by budding as well as binary and plurinary fission. 4. In the midrib of healthy leaves, vascular bundles were collaterally discontinuous. In the diseased leaves, however, xylems were connected to each other and phloem cells showed an atrophy. Granules, which were prominent in the normal abaxial epidermis, were not observed in the peidermis of diseased leaves. 5. Electron microscopy revealed crystals or osmopholic granules in the phloem parenchyma cells, and that normal stacks of grana were not developed in the chloroplasts of infected levels. 6. The disease was experimentally transmitted by grafting. Budding was more effective than crown grafting for transmitting the disease. The disease has been transmitted by grafting even when complete union of stocks and scions has not taken place. The disease agent was not transmitted by sap inoculation. Insect transmission has not been confirmed. 7. Dipping the roots of infected plants into the 500 ppm and 1,000 solutions of either tetracycline HCI or oxytetracycline, HCI was more effective on temporary remision of the symptoms than spraying the 100 ppm and 200 ppm solutions of the same antibiotics. A greater effect was achieved through dipping into 1,000 ppm than into 500 ppm.

붉나무빗자루병은 국내외적(國內外的)으로 처음으로 발견된 병(病)으로서 그 병원체(病原體), 병징(病徵), 전염경로(傳染經路) 항생물질반응(抗生物質反應) 등을 조사(調査)하였다. 1. 붉나무빗자루병의 병징(病徵)은 지엽(枝葉)의 총생(叢生), 기관(器官)의 위축(萎縮), 위황(萎黃), 화기(花器)의 엽화(葉化) 등 빗자루병 특유(特有)의 양상을 나타내고 있다. 2. 이병주(罹病株)의 총엽병(總葉柄) 및 주맥조직(主脈組織)을 전자현미경(電子顯微鏡)에 의해서 관찰한 결과 사관세포(篩管細胞) 및 사부유세포(篩部柔細胞)에서 mycoplasma-like organism 이 관찰되었다. 3. 본(本) 병원체(病原體)는 unit membrane에 싸여 있고 이분(二分), 출아(出芽)에 의하여 증식(增殖)하며 사공(篩孔)을 통해서 식물체내(植物体內) 이동(移動)을 하는 것이다. 4. 이병엽(罹病葉) 주맥(主脈)의 사관세포(歸管細胞)는 위축(萎縮)되었고 각(各) 유관속(維管束)의 사부(篩部)는 분리(分離)되어 있는데 반하여 목부(木部)는 서로 연결되어 있다. 이병주(罹病株)의 엽내조직(葉內組織)은 선상표피(腺狀表皮)가 나타나지 않았다. 5. 전자현미경관찰결과(電子顯微鏡觀察結果) 도관세포(導管細胞)에는 이상결정물질(異常結晶物質), 호(好) osmium성(性) 과립(顆粒)들이 관찰되었고 엽록체(葉綠體)의 grana 구조(構造)가 미발달(未發達)되어 있었다. 6. 접목전염(接木傳染)이 용이(容易)하며 아접(芽接)이 절접(切接)보다 전염성이 높았고 접아(接芽)나 접수(接穗)가 활착되지 않았어도 전염은 가능했다. 그러나 즙액전염(汁液傳染), 충매전염(虫媒傳染)은 부정적이었다. 7. Teracyclin과 terramycin을 처리(處理)한 효과(効果)는 일시적이었으며 영구치료(永久治療)는 되지 않았다. 또한 근부침지(根部浸漬)가 엽면살포(葉面撒布)보다 반응(反應)이 좋았으며 농도(濃度)는 근부침지(根部浸漬)에서 1,000 ppm이 가장 효과적(効果的) 이었다.