Evaluation of Various Primer Sets for the Real-time PCR Detection of Candidatus Liberibacter asiaticus causing Greening Disease in Citrus

Citrus Greening Disease or Huanglongbing (HLB) is one of the most devastating diseases of citrus worldwide which is caused by an unculturable prokaryotic α-proteobacterium, Candidatus Liberibacter sp. Once the bacterium enters the tree, it propagates within the phloem producing die-back, yellow shoots, blotchy mottles on leaves, and off-tasting and malformed fruits (Bove, J. M., 2006). There are three (3) reported isolate types of bacterium namely, Candidatus Liberibacter asiaticus, Candidatus Liberibacter americanus, and Candidatus Liberibacter africanus (Li, W., et. al., 2007). In the Philippines, Candidatus Liberibacter asiaticus is most likely the species that is present among HLB-infected trees. With the alarming incidence of the disease and the fact that there is no available product that can combat the pathogen due to its nature, it is necessary to develop a reliable method that would accurately determine the presence of the bacterium for the integration on HLB management.