APS Homepage

Poster: Diseases of Plants: Disease Detection & Diagnosis


Viability of Candidatus Liberibacter asiaticus in grapefruit leaves at different stages of maturity and Huanglongbing disease symptom development
M. KUNTA (1), E. Louzada (1), P. Vedasharan (1) (1) Texas A&M University-Kingsville Citrus Center, U.S.A.

Citrus Huanglongbing, associated with Candidatus Liberibacter asiaticus (CLas), is the most serious disease in the USA causing substantial economic losses. The real-time PCR (qPCR) assays used to detect CLas have a limitation that they cannot differentiate live and dead bacterial cells. Accurate quantification of live CLas cells in the plant tissue is essential to devise effective disease management strategies and to test the efficacy of new disease control methods. Several optimized quantitative real-time PCR methods using propidium monoazide (VqPCR), a DNA-binding dye, to quantify live CLas populations were described. However, it is unclear if live CLas populations vary with age of the leaf and varying degrees of HLB disease symptom development. To address this question, we have quantified the levels of live CLas populations in grapefruit leaves at different maturity stages and leaves with varying levels of symptoms collected from naturally infected field trees. VqPCR assay results obtained using two different chemistries including SYBR® and TaqMan® will be presented.