Understanding the Physiology of <b><i>Liberibacter asiaticus</i></b>: An Overview of the Demonstrated Molecular Mechanisms

Abstract

Citrus greening disease, or huanglongbing, may entirely eradicate all varieties of citrus cultivars worldwide in the near future. This disease is caused by non-cultivable bacteria of the genus Liberibacter; among them, the more pathogenic being Liberibacter asiaticus. The complexity of the host–pathogen relationship, associated with the impossibility of performing research using axenic cultures, has severely hindered the basic research on microbiology. Since its genome sequence was published in 2009, most of the scientific publications in the field were dedicated to in silico analysis and selection of targets to design early detection methods. The knowledge gained with these approaches felt short to articulate effective methods to control the disease progression. There is a critical need to understand the basic biology of bacteria to design effective strategies to inactivate central mechanisms of pathogenesis. In this review, we summarize the scientific progress made by studying L. asiaticus’ biology through direct experimentation. The evidence collected thus far is not enough to understand L. ­asiaticus’ fundamental biology. It is imperiously necessary to increase the basic research to identify relevant biological clues to control citrus greening. The gained knowledge may also help to prevent potential catastrophic diseases in other crops of significant importance caused by other unculturable Liberibacter species.

Friend or foe? Relationship between ‘Candidatus Liberibacter asiaticus’ and Diaphorina citri

“…As Las is an obligatory intracellular parasite lacking several biosynthetic pathways, metabolic enzymes and secretion systems (Duan et al 2009;Jain et al 2017;Coyle et al 2018), possibly it obtains essential compounds from its hosts. Las infection alters the rate of glycolysis, tricarboxylic acid (TCA) cycle metabolites, respiration rates and ATP content of D. citri (Jain et al 2017).…”

Unravelling the Pathogenesis and Molecular Interactions of Liberibacter Phytopathogens with Their Psyllid Vectors

“…The components of Sec machinery such as SecA, SecB, SecE, SecY, and SecD are conserved in all the sequenced CLso haplotypes. Moreover, CLas and CLso both possess flagella-like appendages and flagellar motor proteins, which might serve as an effector secretion system [51,56,68,69].…”

Bioinformatic Analysis of Potential Pathogenicity Effectors of &lt;i&gt;Candidatus&lt;/i&gt; Liberibacter asiaticus, Causal Agent of Citrus Huanglongbing

“…Given the importance of knowing the mechanisms by which CLas causes the disease, the complete genome of the pathogen has been obtained [8] [9]. This has allowed the study and characterization of various genetic elements of CLas through bioinformatics and experimental tools [10]. Great advances have been made in the understanding of the molecular interaction between CLas and the plant, for example, the presence of a functional ATP translocase enzyme was observed in the genome of the pathogen, which suggests that one of the mechanisms used by CLas is the parasitism of energy from the plant [11].…”