摘要:
柑桔黄龙病病原体为多形态的,圆形的直径为50-500nm,杆状的大小为40-170×200-2500nm,其外界包被的平均厚度为25nm,外层为电子密度浓的暗色层,相似于细胞壁构造,厚度为7-10nm;内层为电子密度浓的暗色层,相似于细胞膜构造,厚度为3-8nm;中间层为电子密度稀的透明层,相似于周质空间,厚度为7-15nm.不论外层细胞壁或内层细胞膜,均由二层质膜构成.经木瓜蛋白酶处理后,在病原体包被的外壁与内膜间的透明层中,可以观察到一层电子密度浓的暗色层,厚度为5-8nm,十分相似于大肠杆菌的细胞壁的外膜与质膜间的肽聚糖层.因此,柑桔黄龙病病原很可能是一种革兰氏阴性的细菌.各种柑桔栽培品种筛管细胞内病原菌体的含量与它们感病性间可能有一定联系.
Abstract:
Citrus Huanglungbin Organism is pleomorphis.The diameter of its spherical body is 50-500ntn, and the size of its rod body is 40-70x200-2500nm.It has an envelope, with 25nm in thickness, which comprises three layers of unit membrances.The outer electron-dense, the inner electron-dence and the middle electron-clear layers are, respectively, similar to cell wall with 7-10nm in thickness, protophasmic membrane with 3-8nm in thickness, and periplasmic space with 7-15nm in thickness.Both the outer cell wall and the inner protophasmic membrane are composed of two distinguishable membranes.After the treatment by papain, an electrondense layer with 5-8nm in thickness was observed under electron-microscope, which is located in electron-clear area between the outer cell wall and inner membrance, and similar to a piplidogly-cane layer between the ceil wall and the membrance of Escherichia coli.According to the presence of piptido-glycane layer in the cell wall, citrus Huanglungbin organism may be Gram-negative bacterioum, there is a relatilve linkage between the quantity of pathogen in the sieve cell of citrus cultivars and their susceptibility.
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