Diagnosis of Citrus Greening Disease by qPCR Analysis

Citrus greening, also known as Huanglongbing disease, is a phloem restrictive disease that affects orange as well as other citrus trees. The disease is caused by the gram negative bacteria Candidatus Liberibacter asiaticus. The bacteria is transmitted by the Asian psyllid, Diaphorina citri. The bacteria causes the tree to produce small and bitter oranges, the roots shrink and the leaves molt. There is currently no cure for this disease. The best way to manage citrus greening is by removing infected trees, implementing healthy planting material and controlling the psyllid population. Quantitative real time PCR (qPCR) was used to verify whether or not a given orange tree had citrus greening disease. DNA was extracted from leaves from eight trees. A qPCR analysis was performed using a primer with the bacteria DNA. Three trees were successfully diagnosed with citrus greening using this method.