Insights into the Huanglongbing pandemic focusing on transmission biology, virulence factors and multifaceted management strategies

Abstract

Huanglongbing (HLB), one of the most destructive diseases of citrus, is caused by the fastidious Gram-negative α-proteobacteria bacterium Candidatus Liberibacter asiaticus (CLas) and vectored by the Asian citrus psyllid (ACP), Diaphorina citri. Currently, there are no highly effective management strategies for HLB. This review focuses on specific aspects of HLB research, including the global distribution of Candidatus Liberibacter species in citrus, HLB status in major citrus-producing countries and plant-pathogen interactions. The elucidation of virulence effectors used by CLas is explored, focusing on the molecular mechanisms that enable the pathogen to manipulate the host plant, and the insect vector ACP to evade their immune systems. Biotechnological approaches and possible management methods for minimizing HLB and ACP risks are reviewed. This review provides a summary of the CLas Sec-delivered effectors, CLas flagellar genes, tight adherence pilus, transcriptional regulators and facilitates the development of integrated and sustainable solutions to safeguard citrus cultivation. © 2025 Society of Chemical Industry.

Keywords: CLas; Diaphorina citri; biotechnological approaches; host–pathogen interactions; management methods; virulence effectors.