水稻白叶枯病菌两类噬菌体性状的比较

 从感染白叶枯病的稻叶、种子和田水中先后分离到24株噬菌体,测定了它们在琼胶平板上形成噬菌斑的大小、血清学反应、热钝化温度、铁盐的钝化作用、寄主范围、一级生长曲线以及在电镜下观察它们的形态。根据测定结果,可将它们区分为两个类群。第一群称为XOP 1型,以OP-3为代表,其噬菌斑直径为3~5毫米,热钝化温度为58℃/10分钟,易为三价铁盐所钝化;寄主范围较窄;潜育期为40分钟,上升期30分钟,平均裂解量为35个。第二群称为XOP 2型,以OP-12为代表,噬菌斑小,热钝化温度68℃/10分钟,对三价铁盐不敏感,潜育期80分钟,上升期50分钟,平均裂解量为8个。它们都是蝌蚪形,但OP-3的尾部细长而不能收缩,OP-12的尾部短粗而能收缩。

COMPARISON OF SOME PROPERTIES OF TWO GROUPS OF PHAGE OF XANTHOMONAS ORYZAE DOWSON

More than twenty isolates of the bacteriophage of Xanthomonas oryzae from leaves and seeds of diseased rice plants and irrigation water of diseased paddy fields were separated into two groups on basis of their morphology and other properties.Phages of group XOP 1(represented by isolate OP-3) produce large plaque about 3 mm in diameter.It is tadpole shaped with a polyhedral head of 65 nm in diameter,and a striated non-contractile tail of 140×18 nm in size.The latent period and raising period are respectively 40 and 30 minutes,and their average burst size is about 35 plaque forming units(PFU) per cell.Phages of group XOP 1 are completely inactivated by heat treatment at 58℃ for 10 minutes,and the unadsorbed free phages of this group are inactivated by ferric salts solution(10^-4M).Phages of group XOP 2,represerted by isolate OP-12,produce small plaque about 1 mm in diameter.It is also tadpole shaped,with polyhedral head of 70 nm in diameter,and a short contractile tail 90×20nm in size.The latent period and raising period are 80 and 50 minutes respectively,and their average burst size is about 8 plaque forming units per cell.Phages of group XOP 2 are conpletly inactivated by heat treatment at 68℃ for 10 minutes.
Serologically they are also different,experemented phages of groupXOP 1 and XOP 2 are specific to Xanthomonas oryzae,but phages of group 2 is much broader in spectrum of its host than group XOP 1 judging from their reaction to different isolates of Xanthomonas oryzae.