摘要:
研究柑桔黄龙病的困难,在于它的病原无法人工培养。因此,长期以来对黄龙病的诊断,主要依据典型的黄梢和叶片斑驳症状。在柑桔园管理不良,缺乏营养或其它病虫混合为害时,便难依据症状作出正确的诊断。这是造成对黄龙病认识上种种混淆的主要原因。70年代应用电镜观察到黄龙病病原(BLO)之后,电镜便成为诊断黄龙病的重要手段。但因病原在病树体内的浓度较低,分布又不均匀,致电镜的检出率偏低。80年代,应用兔丝子将黄龙病BLO转到长春花上增殖、提纯,作为抗原,制备了多抗和单抗的血清,由于多抗血清的效价很低和单抗血清的专化性太狭,均难用于诊断。最近,在病原DNA序列测定的基础上,合成了引物P1及P2,并在引物P1及P2之间合成另一段DNA片段P3作为探针。使PCR(多聚酶链式反应)及Southern杂交技术可能用于黄龙病的诊断。研究结果证明PCR技术比其他方法具有更大优点,能快速而准确地检测出病原；而Q-PCR(竞争性定量多聚酶链式反应)方法则能测定病原在不同样品中的含量,进行定量分析。
Abstract:
Diagnosis and detection are important aspect of citrus Huanglongbing research In the past,diagnosis of citrus Huanglongbing was mainly based on its sympomatology,namely,yellow shoot and mottle leaf During 1977-1978,the causative bacterium like organism (BLO) was found in sieve cells of diseased leaf under electron microscope After then,the electron microscope has been used as a major tool for diagnosis of citrus Huanglongbing disease An improvement came about when it was found that the BLO can be transmitted from citrus to periwinkle by dodder and partially purified by differential centrifugation,which made it possible to prepare antisera,both monoclonal and polyclonal antibodies,for detection and diagnosis of Huanglongbing BLO Recently,polymerase chain reaction (PCR) has been developed for detection and quanfitication of Huanglongbing BLO The PCR-based methods are highly sensitive and effective in detecting the presence of the BLO in diseased plant and insect vectors carrying the BLO Furthermore the BLO in the samples can be quantitated by quantitative PCR making it possible to compare the amounts of BLO in different samples.
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