A new diagnostic real-time PCR method for huanglongbing detection in citrus root tissue

Abstract

Citrus fibrous root tissue was evaluated as an alternative source material for huanglongbing (HLB) diagnosis by real-time PCR using primer-probe set TXCChlb, developed in the present study based on 16S rDNA of “Candidatus Liberibacter asiaticus” (CLas). Real-time PCR data obtained with DNA samples prepared from leaf and fibrous root tissue collected from mature (> 10 years old) and young (4–5 years old) citrus trees growing in Texas and Florida confirmed that root HLB test is more sensitive than the leaf HLB test in terms of the detection rate of HLB positive trees. In addition, the current study confirmed that HLB can be diagnosed at the pre-symptomatic stage using the root HLB test to facilitate efficient removal of HLB-positive, asymptomatic trees that could serve as a source for HLB. The new HLB diagnostic method using root tissue described in the current study can assist in deploying a more efficient disease management strategy to deter HLB spread, especially at the pre-symptomatic stage.