Identification of alternative hosts of the fastidious bacterium causing citrus greening disease

Citrus greening is a severe disease caused by a fastidious bacterium (GFB) residing in the sieve tubes of its hosts. It is an epidemic disease and is spread by insect vectors. In Asia, the Asian citrus psyllid (Diaphorina citri Kuway-ama) is the vector for GFB. For the epidemiological study, an investigation of alternative hosts of GFB was made. Four suitable hosts of the Asian psyllid that are considered as possible alternative hosts of GFB were investigated on graft-inoculation tests. The multiplication of GFB in plants was monitored by dot hybridization using a GFB-specific DNA probe developed previously by us. The results demonstrate that GFB can replicate in Chinese box orange (Severinia buxifolia) and wood apple (Limonia acidissima), but not in common jasmin orange (Murraya paniculata var. paniculata) and curry leaf (Murraya euchrestifolia). Chinese box orange is a good host in which GFB replicates as well as it does in its citrus hosts. Wood apple is a transient host in which GFB exists temporarily and disappears several months later. Common jasmin orange and curry leaf are not hosts of GFB as they showed no detectable signals in dot hybridization tests throughout 1 year of experimentation.