Cochin China atalantia (Atalantia citroides) as a new alternative host of the bacterium causing citrus Huanglongbing

Abstract

Through graft inoculation and psyllid transmission experiments, the Cochin China atalantia (Atalantia citroides) was found to be a new alternative host of the fastidious bacterium (Candidatus Liberibacter asiaticus = Las) causing citrus Huanglongbing (HLB). The Las pathogen is commonly transmitted by Asian citrus psyllid (Diaphorina citri) in persistent manner. The Cochin China atalantia plants locally called wild lime (WL) including elliptic leaf (WL-1) and elongated leaf (WL-2) types are growing wildly in Cambodia and Cochin China of Southern Vietnam. The Las pathogen infected Cochin China atalantia plants by graft inoculation and psyllid transmission, and survived persistently. The Las was transmitted from Las-infected Cochin China atalantia plants of two types to healthy citrus plants (Ponkan mandarin) and atalantia plants through psyllid transmission. Therefore, the Cochin China atalantia plants of two types may serve as a new alternative host of Las. Higher titer of Las was detected in the Las-infected WL-1 atalantia plant which developed typical yellow mottling symptom, while lower titer of Las was detected in WL-2 atalantia plant developing mild chlorosis symptom.