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| Huanglongbing(HLB) is one of the most destructive citrus diseases worldwide, in which the uncultured phloem-restricted α-proteobacterium ‘Candidatus Liberibacter’ is always associated. A Taqman real-time polymerase chain reaction (RTi-PCR) assay method specific for ‘Candidatus Liberibacter asiaticus’ (Las) has been developed previously. In this study, the RTi-PCR was used to examine and dynamic monitor the distribution of Las in the infected citrus plant and insect vector, citrus psyllid (Diaphorina citri). Quantitative analysis of Las titer indicated that it was distributed unevenly in plant and psyllid, and basically, those sections with more sieve-tube tissue had more pathogens. Dynamic analysis results showed that the titer has a significant change throughout a year in citrus leaf mid-vein and psyllid vector. Understanding the distribution and dynamic change of the bacterium inside the citrus tree and psyllid is critical for HLB research work like transmission mechanism and field epidemic regulation. The results in our study show that RTi-PCR is an excellent tool for quantitative diagnosis of HLB pathogen, as well as for monitoring the pathogen and assessing resistance and tolerance to Las in citrus breedings. Furthermore, the RTi-PCR is also an efficient technique to quantitatively evaluate the other endophytic bacteria in their host. |
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| Keywords:Citrus greening;Huanglongbing;Candidatus Liberibacter asiaticus;psyllids;Quantitative monitoring;Real-time PCR |
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