Mycoplasma-like Organism Associated with Witches'Broom of Ipomoea triloba L. in Taiwan

Abstract

臺灣之紅花野牽牛簇葉病（Ipomoea triloba witches’broom）係作者於1983年在南投地區發現之新病害。病株叢生小葉、綠化花，顯現異常分蘗之典型簇葉病徵。田間採集之病株葉脈組織超薄切片之電子顯微鏡觀察結果，篩管細胞內，有多數多形性擬菌質體（mycoplasma-like organisms）之存在，呈楕圓形、球形、圓形及長管形等大小不同之各種形態，，球形或楕圓形之直徑約140～750nm，長管形的約120～240 × 1750 nm，健全株則沒有發現擬菌質體。病株之莖葉切片，同時經 Dienes’stain 染色，並以光學顯微鏡觀察，結果在罹病篩管細胞內，顯現專一性藍色之 Dienes’stain 染色反應，健株者則無此反應。此項專一性染色反應，表示其擬菌質體在篩管細胞之存在，而其存在位置及數量與電子顯微鏡觀察結果相似。以上結果顯示擬菌質體似為I. triloba簇葉病之病原。 The witches’broom of Ipomoea triloba was a newly recorded disease found in Nantou county incentral Taiwan in 1983. The diseased plants showed typical witches’broom symptoms comprising bushylittle leaves, green flowers and abnormal conical shoots. Numerous pleomorphic bodies characteristic of amycoplasma-like organism (MLO) were observed in veinal sieve elements of the diseased leaves underelectron microscopy. They were spherical, ovoid, ellipsoidal or filamentous, about 140 to 750 nm indiameter. Filamentous bodies were about 1750 nm in length. No such MLO bodies were found in thehealthy plant. The stem and leaf sections were also examined under light microscope after treatment withDienes’stain. The specific blue staining reaction was noticed in affected phloem cells, but no such reactionwas detected in those of healthy. The result of staining which revealed the presence of MLOs in the sieveelements is in accord with what was observed by electron microscopy. We suggest an MLO etiology forthe witches’broom of Ipomoea triloba.